BMW e34 OBC retrofit

	Cost: $100? Difficulty: Time: 3 hours
Procedure courtesy of Damian Bannon
If your BMW E34 came from the factory with either an analogue clock or a digital clock/outside temperature combo it is possible to upgrade to the full On Board Computer (OBC). The clock units use the same connector as the OBC and all the wiring is already in place. Cars that had only an analogue clock do not have the outside temperature sensor mounted, so this function will not work, but all the other signals come from the ECU. Cars that have the instrument cluster with no check control will most likely have no gong so the OBC will stay quiet about ice and speed limit warnings and give a visual warning only. All other functions should work as expected - including the CODE start blocking!
Part numbers:
The first step is to find an OBC unit - These can be got from the stealer (P/N 65 81 8 351 055) but are big $$$ so the best bet is to find a used one from a breaker's yard or similar. An OBC from any BMW E34 model will do - even a BMW E32 OBC will work but as the 7 series has a bigger petrol tank some calculations such as 'range' may be incorrect. Other parts you may want to get are the turn-signal switch which has the OBC remote control on the tip and the new radio/OBC holder. The OBC will work fine without installing the new turn-signal switch and will still blend its notifications into the check control display. The mounting frame (holds together the clock or OBC as well as the radio and heater control module) differs for OBC vs clock equipped cars as the slot for the OBC is deeper than that for the clock, the OBC is approx. double the depth of the clock and the connector is located higher than on the clock. It is possible to cut away the plastic at the back of where the clock sat to allow the OBC fit but the ideal way is to replace the mounting frame. The part numbers for the two frames are: Holder radio/OBC 65 81 1 384 121 Holder radio/clock 65 81 1 384 141 Note from David, modified by Durham, Paul L (UK): The e34's have 2 different types of OBC one for the BMW 518i,520i and a different type for the BMW 525i,530i,535i,540i. There are two types of OBC but you can fit ANY OBC IV (without the coding plug socket) into a 518 or 520 with a little modification. I successfully retro-fitted an OBC IV (with GONG and Temp Sensor) into my 1995 520SEi where the OBC DID NOT have the coding plug socket in it and it's fully operational. All the OBC IV's out of higher spec cars eg.525, 535, etc (without coding plug socket's) are technically dumb on their own as they have no information about the car's engine type, etc. This means you go to BMW (like i did) and buy a coding plug for £20 (UK). BMW need to know Year, Model, Petrol or Deisel, Plastic or Metal Fuel Tank so that the coding plug has the correct calculation's for your engine, eg. MPG,etc. You then take the coding plug apart so your left with a mini PCB. You then open your OBC and solder the mini PCB onto the back of your OBC. It's only 6 pins and is super easy to do. Your OBC will now know what your car is (NO PPPP ERROR) ! The info on how to do this is in this PDF File here : http://gunnar525.de/schraubereien/bc4_umbau_codierstecker.pdf It's in German but the pics are easy to follow. Once you get past this stage you can then carry on with the retro-fit.
Procedure
Second step is to remove your old clock - To do this, remove the radio and the radio's mounting case and then reach inside the vacant radio slot at the side next to the clock, at the top you should feel a little lever (position marked by red dot on remove_clock.jpg) which you need to press (push it towards the engine) and the mechanism should make the clock move out towards you and you can then pull it out the rest of the way with your fingers. The third step is to try the OBC to see if it works - The connector is clipped into the back of the mounting frame, unclip this and pull it out a bit (there should be an inch or two give in the wiring) and then plug it into the back of the OBC. Turn the ignition on and see if the OBC comes to life. Clock removed If the OBC doesn't come up the next step is to figure out why. The list of connections is given in the table below so start by checking that there is +12v at pins 6, 8, 9 & 17. The most likely culprit is pin 17 as there will be no power to this if your car doesn't have the auxiliary horn relay installed and without power at pin 17 the OBC will play completely dead. If there is no power at pin 17 an easy solution is to cut the red-grey-yellow wire that goes to pin 17, cut it as far from the connector as possible to make life easier, and join this to the red-yellow (red with a yellow stripe, there's also a yellow wire with a red stripe!) wire that provides power to pin 9. You could join these via a 5 or 10 amp fuse if you prefer and it may be no harm to tape off the end of the red-grey-yellow wire coming from the car so it can't cause any problems. Digital clock/temperature indicator --- pin4: ground pin5: blue/red/yellow, temp sensor pin8: + from fuse F1 pin9: + from fuse F20 pin18: white/blue, chimes pin19: white/red, chimes pin22: grey/red, light switch OBC --- pin1: violet/green/yellow, alarm system pin10: black/green, starter pin6: + from fuse F17 pin9: + from fuse F20 (red/yellow) pin8: + from fuse F1 pin22: grey/red, light switch pin25: yellow/red, turn signal switch pin3: white/yellow, diagnostics pin16: white/violet, diagnostics pin14: white/grey, instrument cluster pin7: black/white, instrument cluster pin4: ground pin5: blue/red/yellow, temp sensor pin20: black/red/yellow, pre-ventilation pin21: black/white, pre-ventilation pin23: violet/white/yellow, alarm system pin17: red/grey/yellow, alarm system pin26: black/red/yellow, fuel tank level sensor pin12: brown/violet, fuel tank level sensor pin11: white/black, DME pin24: black/violet, DME pin19: white/red, chimes pin18: white/blue, chimes pin15: white/brown, radio pin2: blue/brown/yellow, radio Once the OBC is working, the next step is make it fit properly - You can either replace the mounting frame with the one designed to hold the OBC or alternatively you can cut away the plastic at the back of the original mounting frame (This can even be done without removing the mounting frame if you are careful by using a suitable saw from the front) so that the OBC will slide in all the way until the front of it is flush with the console. Next, you need to set the country setting for language, miles/km, C/F and l/100Km / Km/l. - To do this you need to access the OBC test menu by simultaneously pressing the 1000 and 10 keys so that the display changes to "TEST". With the 10 & 1 keys enter 11 on the display and then press the S/R button. "0 LAND" should now be on the display and you can alter this by using the 1000 & 100 keys and the S/R to save. The settings are from "0 LAND" to "9 LAND" and through trial and error you should be able to find the setting that is best for you. Also, some settings use US gallons while others use European gallons so take that into account. If the OBC appears to be reporting inaccurate fuel consumption figures it can be calibrated to give the correct values. - Fill the fuel tank to the maximum and reset the trip counter and one of the OBC's average fuel consumption monitors. Run the fuel tank nearly empty and fill the fuel tank again to the maximum. The amount of fuel it now takes to fill the tank is the amount used to cover the distance recorded on the trip meter so, from this, work out the actual fuel consumption of the car and then compare this to what the OBC reported as the average fuel consumption. If these two average fuel consumption figures are not exactly the same then you need to calibrate the OBC by entering a new correction factor. The fuel consumption correction factor is a locked function of the OBC so before you can access it, you must first unlock the OBC - Access the OBC test menu by simultaneously pressing the 1000 and 10 keys so that the display changes to "TEST". With the 10 & 1 keys enter 19 on the display and then press the S/R button. Add the current day and month (as it is known to the OBC) and enter this value and then press the S/R button, the OBC should now be unlocked. To access the fuel consumption calibration factor you once more need to simultaneously press the 1000 and 10 keys so that the display changes to "TEST". With the 10 & 1 keys enter 20 (Be careful not to enter 21 as this will reset the OBC) on the display and then press the S/R button - you should now see something like 1000 CORR, this is your current correction factor. To calculate your new correction factor use the following: new_correction_factor = old_correction_factor * actual_mpg / obc_mpg Enter your new correction factor into the OBC using the 1000/100/10/1 keys and then press the S/R button. If you want to relock the OBC - enter function 19 again then press the C/F button to lock. Much of the information contained above came from internet posts by: Priit Varik, Mark M and Al and from http://home.iae.nl/users/bts/obc.htm More info from Mark about temperature sensor: I have a 1990 E34 525iA SE (UK spec) that was originally fitted with an analogue clock. Following your instructions I removed the clock and fitted a used OBC. This worked fine, but had the annoying problem of sounding the gong every time the ignition was switched on due to the external temperature sensor not being fitted. Well, after a while this just because too much, to after some investigation I found that the wiring harness for the temperature sensor was indeed fitted to the car. It was located behind the radiator in the same place where the horn is mounted, i.e. in the centre of the car, behind the grill in between the lights. The wiring harness was coiled up and clipped out of the way. Once I had released the clip, it was then just a simple case of plugging in my new temperature sensor to the harness and it worked first time. I did try to route the sensor somewhere away from the radiator so it would measure the external temperature, not the radiator temperature ! The only trick that the old girl had left was that it seems to take a few hours for the OBC to register the correct temperature. It crept slowly up from -39oC to the correct outside temperature. I'm assuming that there must be some kind of digital or analogue filter on the system that has a very large time constant. Anyway, once it had reached correct temperature it seems to operate correctly, agreeing with roadside temperature signs. More temperature sensor from Mark A. I finally got bored with the display telling me it was -34 outside, so I ordered the temp sensor from BMW main dealer for only 17 pounds UK. Took the front off the car & spent hours searching for the magic wire to connect it up. Needless to say, it wasn't there. It would seem that mine (94 525 European spec) didn't have it fitted. The solution is to run a wire from one side of the sensor to earth (ground) & the other one thru the car & splice it in to pin 5. All now works ok. Just thought this may be useful to anyone else doing the retrofit & thinking they're going mad as the cant find the missing wire. More info from Andy: The OBC will chime every time you turn on the ignition and give you a -34 degrees warning if you don't have or fit a temperature sensor. I thought mine had a fault until I searched a few sites. More info from Martin M. The user should check the wiring loom into the back of the clock. If it has a 'bunch' of wires then your ok, if it contains only three wires (as is the case withe my E34) then it is not possible. More info from Tom Bosman: Having just retrofitted an OBC to an 89 525i (thanks to your notes) I would like to pass on a little additional info re a problem I encountered. As part of the retrofit I also purchased an indicator stalk (turn signal) with switch. When I pulled the old one out and compared it with the new one there were a few differences (besides the extra wires for switch). The old switch had a relay attached to the 12 pin plug which strangely had no output. One of the wires of this relay was on the same pin as the yellow/red wire on the new switch which operates the dash display from OBC. After trying the switch as is and it not working I then wired it up the same as the old switch and then had a yellow/red wire floating free. After some further investigation I discovered another connector under the socket for indicator stalk connection which had a yellow/red. I traced this wire back to pin 25 of OBC which is the trigger for dash display. After connecting my spare yellow/red to this the dash display now worked. I also discovered that the relay with no output was merely connected to the flasher to make it audible. Without the relay the flashers worked perfectly but were silent. Hope this can be of help to some others who have trouble with indicator stalk switch.

Keyless Entry on BMW e34

	Cost: $50 to $100 Difficulty: Time: 1-2 hours
Procedure courtesy of Russell Jones and photos of Anthony
Having just fitted a keyless entry system to my 5 series I thought I'd scribble it down so that other people can have an easier time doing the same thing! As my car is a UK version, to save confusion instead of referring to the driver's side or the passenger side, I will call it the RIGHT or LEFT, from the perspective of standing behind the car looking forward to the front. Only use a multimeter for testing the wires, as these have a high impedance and won't short anything out. DON'T use a test light (screwdriver with a croc clip and a bulb type) as this can mess up delicate circuitry. The System: I bought the Omega Research ATV 2100 system from www.mypushcart.com for a very reasonable £58 including what they call a DLS (basically 2 pre-wired relays to convert the standard NEGATIVE output to a POSITIVE output) and two additional relays - I'll explain what these were for and why I didn't use them later.
Wires

I wired in the pre-wired plug (that connects to the unit) first, before plugging it in. On the unit itself: · RED - Constant 12v I first crimped a forked terminal onto the RED wire. On my car, under the back seat (pulls up) on the RIGHT there was a black plastic housing (looks identical to the fuseable link box in the engine bay) with a big red wire going in and bolted to a big black wire going out. I carefully opened the plastic cover and loosened the nut - with a socket, making sure you don't touch any metal other than the nut! Then slide the crimped terminal under the nut and do the nut up again. I was careful not to break the connection made by the red wire incase it affected any of the cars systems. · BLACK - to NEGATIVE / GROUND Again, crimped a fork terminal on the wire first. On the metal 'wall' next to where the RED wire has just been connected, there should be a nut (probably with paint on). If you undo this you'll be able to slide the forked terminal in and do the nut up again. I measured this to check if it was a good ground, and it was fine, as the nut and the face it tightens onto are bare metal - no paint! · YELLOW - to switched 12v (comes on when ignition is on) This was a bit trickier to find. On the LEFT of the space under the back seat is the central locking control unit and some orange relays. Using a small screwdriver you can release the little tab holding the 3 relays in place and lift them up a bit to inspect the wires going into them. I think that it was the middle of the 3 relays, but not sure, that has Purple/Black wire (looks a bit fatter than the others) going into it, which showed on the meter as going on and off with the ignition, so I opted for this one. By the LEFT corner you'll see a load of wires... find the Purple/Black fat one! Once I'd found it, I used a Scotch-lock (SL) (one of those plastic clips with a metal insert that you clamp over the two wires you want to connect) and just clamped it onto the wire so I could measure it again to check. Proved OK, so undid the SL and put the YELLOW wire in and clamped shut to connect them both. I didn't use the GREY or ORANGE wires, so cut any exposed wire off them and then taped the ends with insulation tape.

The DLS Unit:

The DLS unit is basically just 2 relays wired together - although for the OMEGA unit, it has a 3 pin red plug wired into it. The OMEGA (and so do many other, so check when you are buying) produces NEGATIVE pulses to lock/unlock the doors - but the BMW E34 needs POSITIVE pulses. I think this applies on most models, and also on the 3 and 7 series…but don't hold me to that! The DLS converts the negative pulses to positive pulses. Here's the wiring for those that need to know these things! Click for larger version

LOCK / UNLOCK WIRES and Dead Lock System:

Right then, this was a pain…coupled with the fact that the instruction booklet is not set out particularly well, having the worded description for the positive pulse wiring underneath the diagram for the negative pulse wiring….well, I blew one of the fuses by reading the words & following the diagram! Here's the correct diagram (the 2 SPD relays are the 2 relays attached to the DLS!) Click to see larger version 1. Open the boot (or 'trunk' if you prefer!) and undo the 4 plastic screws (each move a ¼ of a turn) on the trim on the boot lid itself. Unhook it over the rubber bump stops and pull it dow so you can see the lock mechanism and wires and bits. Make a note of where the solenoid is before you undo it, as the position is important for it to work properly. The solenoid is held in place by 2 brass looking bolts (about 6 or 8 mm) - you should be able to see the near the black latch on the inside of the boot lid. By the key lock barrel (on the inside) you will see a bar with a 900 bend the end that sits in a plastic bush - this bar is attached to the solenoid and you need to push the bar out of the bush before the solenoid will come out. Undo the two nuts and remove the solenoid, leaving the wires plugged into it! It's a bit of a fiddle, and is easier if you take the connecting bar out of the solenoid end as well. 2. With the solenoid out, you can open the top of the connecting plug to reveal the wires, which convieniently have round holes in to poke the meter into! By locking and unlocking (pull and push on the solenoid you've just got out) you can measure the voltages on the 5 pins exposed. Here's what I found: RED/BLACK +12v all the time WHITE +12v pulse when locked, then 0v at rest in locked position. WHITE/GREEN +12v when unlocked / 0v when locked / 12v when actuator at rest unlocked BLUE +12v Pulse when unlocked / 0v when at rest in unlocked position WHITE/BLUE +12v when locked / 0v when unlocked / +12v when actuator at rest locked When DEADLOCKED with the key: · All 0v except WHITE/BLUE and RED/BLACK, which showed +12v The two additional relays (not the DLS) that I mentioned I didn't use, are for if you want to protect the solenoids from damage that can occur if the door are deadlocked with the key, then tried to unlock by the remote. I didn't do this, as the deadlocking had ben playing up and I didn't want to use it anymore. If you don't install these relays just remember when you've deadlocked the car! www.mypushcart.com can e-mail you the diagrams if you want to fit them. All the wires go back to the load of wires by the central locking control unit, and it will help matters if you can get some of the tape off to make it easier to separate the wires. This is how I wired it up (again, using Scotch-locks), and everything is working fine: DLS Wire Central Locking Wire GREEN WHITE / BLUE BLUE WHITE / GREEN PURPLE RED / BLACK DLS Wire Central Locking Wire Green White/Blue Blue White/Green Purple Red/Black I did the testing the wires with the SL crimped on first, before connecting the wires…..just to be certain! Once everything was plugged in, I programmed the unit as per the instructions supplied. Finishing Off: The DLS relays I mounted on one of the screws on the central locking control plastic cover. One screw is easily accessible and is nearest the back of the seat…you can't miss it. I took this scerw out, put the DLS relays in between the 2 halves of the plastic cover and lined up the hole in the relay with the screw hole, then put the screw back in to clamp it in place. The relays are really light, so I figured this should be ok. The main unit itself has two mouting tabs with holes in. Just above where I connected the black GROUND wire, there is a threaded bolt hole - I found a bolt with the same thread and fastened the unit to the metal 'wall' securely. Again, it is not heavy at all and was held very firmly in place. The aerial wire. I pulled off the rubber/felt trim around the door frame and then fed the wire into it and pushed it back in place, so the wire ended up sealed in around the door frame - which gave quite good reception and was nicely out of the way. Things to Note: The system CAN operate the full closure system should your E34 have it (normally operated by holding the key in the lock or deadlock position). When the system is wired as described above, the full closure will not work. The reason for this ( I think) is that the boot (trunk) lock doesn't operate the full closure when using the key - hence as the system is wired up off this set of wires, the full closure won't work. If you can be bothered to try and figure out the lock/unlock wires from in the drivers or passenger doors, I guess it should work. I just decided that it would be considerably easier to use the boot lock wires, and also I quite like to leave he sunroof or windows slightly open in the summer when locking the car up. REALLY IMPORTANT>>>>>(my disclaimer!) What I have described I in these pages is EXACTLY what I discovered, tried and did, and I hope that it will help others. As we all know, new BMW bits are not cheap, and I was very worried about damaging solenoids or the central locking control unit. AS MUCH AS I HOPE THIS HELPS, IF YOU ARE UNSURE, CHECK WITH AN AUTO-ELECTRICIAN OR YOUR LOCAL ALARM DELAER AS I WOULDN'T WANT ANYONE BREAKING THINGS…..THIS IS AFTER ALL ONLY MY TAKE ON THINGS AND I DON'T DO THIS FOR A LIVING!

More Diagrams and info:

Negative pulse door circuit & DSL Positive pulse door circuit $ DSL (should be the right diagram for the BMW E34 - E32) BMW Deadbold door lock circuit BMW pre-wired factory alarm connector Niels website: http://bmwe34.barracuda-central.org: Complete BMW Wiring-schematics online E34 cars and experience of his keyless entry.

More info on the keyless entry:

All, I installed my keyless entry system last night. I thought I'd pass on what I learned in the process. It's cheap, easy, and quick if you know what you're doing. First, all E34's have positive trigger or output for the door locks! Many other cars have negative trigger. So, you need a keyless system that can do positive trigger or you need to buy a few extra parts to turn the negative trigger system into a positive trigger. I bought my keyless entry system from www.mypushcart.com. It was the Crimestopper 845RKE. It cost $40 including priority mail delivery. But, it doesn't have positive trigger. So, I had to also buy two 30 amp relays and the prewired sockets for them. I bought the relays and sockets from a local car stereo and alarm place for $7.50 total. You can also go to a place like www.audio-etcetera.com and buy two 30 amp relays (CRI-CS-402A, $1.66 each) and two prewired sockets (CRI-CS-SRS, $0.96 each). It's easy to wire in the relays - the manual that comes from Crimestopper shows you how. If you can follow a map, then you can wire this in. Crimestopper also makes a model 855RKE that has the positive trigger built in (other manufacturers also have them). I could have bought that and saved myself a little grief but I didn't know I needed positive trigger. Basically, when installing the system, you need to find a ground, a constant +12 volts, the lock wire and the unlock wire. If you want your locks to lock when you start your car and unlock when you shut it off, then you also need to find a +12 volts that comes on when the engine is running. I didn't wire mine up to chirp the horn or flash the lights so I can't help you there. It also pays to buy some low voltage tap-ins. I got a package of them from Radio Shack (#64-3053) for $1.69. They allow you to crimp your keyless entry wire onto the existing wire rather than cutting into the wire and soldering. You just squeeze them on with a plier. I've had good luck with them. Disclaimer: What follows is my take on things. I am not an engineer. Don’t hold me responsible if you blow a fuse or something. I’ve been as careful as possible, but verify what I’ve written by looking at your own Bentley manual or by talking to a pro or another person who’s done this. End of disclaimer. For '92, ’93, and '95 E34's, the system installs under the back seat on the passenger side. Look for the 12-pin plug near the battery where the alarm module would plug in. The lock wire is white/red/yellow dots. The unlock is blue/red/yellow dots. The brown/orange wire is the ground, the red/gray wire is the constant +12 volts, and the violet/white wire is the one that is +12 volts when the car is running. 1994 E34’s are the same as above except the constant +12 volts is yellow wire on the alarm plug and the ground is brown. Sorry, but my Bentley’s doesn’t show which wire is the +12 volts when the car is running. For '89 through '91 E34's, the system installs in the kick panel near the driver's left foot. The lock wire is white/red/yellow dots. The unlock is blue/brown/yellow dots. You should be able to find a red wire for the constant +12 volts (here’s when a cheap multimeter is handy) and a small screw or something for the ground. I don’t know where to find the +12 volts that is hot only when the engine is running. The systems usually come with an LED that blinks to help you program the system and it blinks when the car is locked. I figured it may serve as a theft deterrent so I installed it in the plastic panel that is behind the right calf of a passenger sitting in the back seat on the opposite side of the car from the driver. I led the programming push button up behind the seat so it is behind the center armrest in the back seat, behind the cover that's held up with Velcro, and even behind a small flap in the rubber sound-deadening material (my car doesn't have the ski boot). I didn't want to have to pull up the back seat to re-program the remotes or the system. I hope this helps. I'm not affiliated with Crimestopper or mypushcart.com or audio-etcetera.com. They were just the places I found on the web. There are a lot of good systems out there. Any of them should work as long as they do positive trigger (or you buy the relays and sockets and spend an extra 20 minutes wiring them in). Chris I. Clearwater, FL '95 525iA with keyless entry! Double-locking (at least in my '92 525i) is triggered by sending 12V to both the lock and unlock wires at the same time. All you need to do to enable double-locking is to solder a diode between those two wires. A cheap 1n5401 (available at Radio Shack) will do the job just fine. Solder the end of the diode with the solid line on it to the unlock wire, and the other end to the lock wire. The diode lets the voltage go to both wires when locking, and only the unlock wire when unlocking. It works by letting current flow through the diode from the lock wire to the unlock side during the lock process. Then it blocks the current to the lock wire when the unlock wire receives power. If it works backwards, then change the orientation of the diode. I have an alarm system that I bought from my local electronics wholesaler for about $60. It has most of the features of the big name alarms like code jumping, lock when the ignition is turned/unlock with key off, flashing lights, dual-level aux input, etc. The cool thing is that when the doors lock when I start my car, they don't double-lock -- there must be some logic in BMW brain somewhere that prevents the car from double-locking with the key is in the ignition. I hope this helps! Lito Reyes '92 525iM Sharked! Here's what I came up with. This should apply to '92/'93/'95 E34's. Like Chris said, if you explode your car or something, it's your own damn fault :) Please note that it's entirely possible that my cause and effect is faulty. This is just what I traced down using a trusty test light. BTW, a test light like mine is handy for this kind of work. It's one of the ones that looks like a screw driver with an alligator-clip wire emanating from the top. The real secret is that it eliminates those pesky short circuits because it just lights up if you are connecting opposite polarities. If you alternately hook the alligator clip to positive or negative, then you can probe for triggers because the bulb's filament completes the circuit, and the trigger circuits don't even pull enough current to light it up. This obviously isn't a good idea where sensitive/high-impedance drivers are involved, i.e., fuel injector circuits in some cars or airbag wiring; in those cases, dig out the DMM. Wire Color* Function brown/red timed dome lights (~7 sec) (-pulse)** red/white ? shows neg always blue/red unlock (+pulse) white/red lock (+pulse) blue/green blink parking lights (- pulse) black/blue ? shows no signal brown/violet goes (-) when either rear door opened brown/blue goes (-) when either front door opened brown/white timed dome lights (~15 sec) (-pulse)** brown/orange ground violet/white + when car running red/gray + constantly *most wires also have little yellow dots on them **dome rocker switches in the forward position In my case, I have a DEI keyless entry that came with all kinds of goodies I probably won't use. I will mention some of the features I did use, and how. The great thing is that you don't have to go anywhere except the plug under the rear seat. I'm pretty anal retentive and solder in everything instead of using taps; even so, the actual installation only took about 30 minutes. 1. Unlike some systems, this one supplies both positive and negative signals for lock/unlock. Unfortunately, this isn't done with four separate wires, but with two. How? Each wire does double-duty, carrying the inverse of what the other does; for example, one wire is + lock, - unlock. The other is the opposite. This causes a bit of a problem when trying to do the double-lock action, since a single diode would still cause a short circuit between the + of the lock circuit and the - of the unlock (remember the other is always inverted). While DEI might have put in circuitry to eliminate this problem, I wasn't taking chances, so I used two diodes to eliminate the possibility of + current going "back up" the unlock wire (see lower circuit in diagram). This might not be a bad idea even if your unit doesn't reverse polarities, as the driver might still be sensitive to the onrush of current. Thus far, we have lock and double-lock (whoo-hooo). 2. ...But we don't have window/sunroof rollup. That's because my keyless unit only supplies a pulse for lock, not a constant signal. This can be overcome (apparently) with add-on units that DEI supplies, but I don't have no stinking time to wait around ;) To add insult to injury, you can't program this system to perform more than one channel function for the same key (separate channels are controlled by either separate buttons or unique combinations of two buttons pressed simultaneously). I reasoned that it wouldn't be a *bad* use of the auxiliary button to perform the rollup feature. The auxiliary channel supplies a (-) signal as long as the button is pressed. As a side note, I also couldn't just reprogram the auxiliary channel to the lock button, because the unit needs a "proper" lock signal to perform all the housekeeping it does (start blinking the LED, flash lights, honk horn, whatever). First the (-) signal was converted to (+) using a relay. Then a couple more diodes were utilized to merge the unlock and aux signals without screwing something up (upper diagram). BTW, I happened to have about 20 of these diodes around, I bought a pack of 25 a while back for another project :) So now, you lock with the lock button, then press the aux button to roll up the windows, etc. I'm not sure what the current draw would do to an alarm system, though. It might think things are locked up and something is malevolently using electricity. 3. All the other DEI channels are (-) trigger, so I plugged them straight in to the dome light and parking light wires. I could have triggered the domes on unlock from the lock wire (remember that inversion thing?), but decided to use the "progressive unlock" channel. This is normally used to unlock the driver's door on the first press of the unlock, and the rest of the doors on the second press. Now I can control whether the domes come on before the door is opened, by pressing the unlock a second time. 4. It's not horny :) Even though I'm sure the factory system has horn blip confirmation, I couldn't find a wire from the rear of the car to perform this function. Even if it did, the horn relay only gets its constant + when the key is on (the horn button supplies the -). Actually, supplying the horn relay wire with a + positive signal when the car is off will honk the horn. I don't know if this is by design or if the other side of the relay is grounding through the windings or filaments of other items in the same power circuit. Don't laugh, the a/c relay on my Triumph is wired that way on purpose. Since I was putting the lower dash back together, I tapped into the relay wire and stowed a bundle under the carpet panel next to the console, for future use without taking everything apart. 5. I took advantage of the opportunity to wire in a few other indulgences. These are items that it would be foolish to post on the World Wide Web! Let's just say that I made thieve's lives a little harder.

OBC Parked ventilation retrofit on BMW e34

Parked ventilation is a special function of the OBC. It allows you to have the ventilation running while the car is parked and the doors locked. This is handy for these cold winters or hot summers. The drawback is the older E34 are not equipped with this function, even though it is expalined in the owner manual. So you've read everything you can about parked car ventilation. You've futzed with your OBC timer button in myriad combinations, hoping that just once, once, you'll see "VENT". You've read about other's frustrations and successes. OK. I'll stop. if you've been lusting after this feature, you'll be happy, too. Because it is NOT rocket science. It takes about $15 worth of parts plus I'd guess it'll take about 2-4 hours of your time depending on how familiar you are with how to remove and replace the: glove box, glove box cover, passenger front (by firewall) foot venting and: associated cover, radio, OBC. You also, I believe, should have a rudimentary understanding of or facility in DC circuitry, Ohm's law, counting and soldering. The second may not necessarily be a requirement. You should know how to read Bentley wiring diagrams, if only to understand how this fits in. My disclaimer: I do not warrant that these instructions are correct. I furthermore assume absolutely NO responsibility, fiscal or otherwise, if you decide to do this procedure and end up frying something in your car.

How does it work? (Thanks to Ray)

You call it "fresh air feature". Assuming you are referring to what I know as "parked car ventilation": 1) the feature is not temperature dependent. It will work winter or summer. 2) the feature will not activate unless the ignition key is in position "1". I.e., the ignition must be off, but your ignition key must be turned on suffieiently to unlock the steering wheel. 3) in early E34s, in all early 750iLs, and in all later E32s, the OBC's "timer" function key has a dual function, which was activated by "toggling" the timer button to the left or to the right. Toggling to the left activated an elapsed time function, but is not in effect on E34s post-1993 (except in the 540i), even though it is described in the owners manual. (Don't ask me why.) Removing the elapsed time function allowed the "timer" function to store 2 parked car ventilation start times. 4) when you press the timer button repeatedly, does it scroll 3 messages? The LED should display "OFF Vent", "--.--t 1am", and "--.--t 2am" in succession. 5) there is a way to test whether this feature is working: With the ignition key in position "1", press the timer key to obtain the message "OFF Vent" in the LED display. While continuing to hold the timer button (and the "OFF Vent" message in the display), press the "temp" button. Hold both buttons for 5 seconds, the release both buttons. The LED should now display "1N Vent". Next, press the "S/R" button. A motor should whir (opening the fresh air vent)and the blower should start. Pressing the "S/R" button again will turn off the ventilation. Or, you can now remove the ignition key and either press "S/R" to turn off ventilation, or allow ventilation to continue until is shuts itself off after 15-20 minutes (I forget which). If the test procedure doesn't work, but your heat/ac system works and the OBC works otherwise, there is probably a broken or corroded connection between the OBC and the heating/ac controller board. It mught correct itself if you remove and reintall the OBC's and the heating/ac board's connectors. If this doesn't cure it, forget about "parked car ventilation"!

Procedure

Phillips screwdriver. hex key to remove radio Needlenose pliers Diagonal cutting pliers Soldering iron Good tin/rosin solder Supply of 14 AWG stranded wire. I'd recommend red, black and green insulation "vampire" wire connectors for connecting a wire to an existing wire without cutting the existing wire Radio Schlock 275-218 DPDT relay (an SPDT will work also) An ohmmeter (DVM, preferably) Before you start work, REMOVE THE NEGATIVE BATTERY TERMINAL FROM YOUR BATTERY and ensure that your ignition is in the off position (remove the key). If you don't, you may only blow a fuse. But you could possibly blow your OBC. Or something else. Given Murphy's ubiquity and caprice, you'll likely nail something (or things that are) very expensive. 1. Remove the glove box and set it aside (see Bentley's, 513-4) 2. Remove the glove box cover (three Phillips screws: as you look towards firewall, right, left near glovebox latch, left near rear), disconnect the light and the switch. Don't break the plastic tabs at the rear. Slide it towards you. Set it aside. 3. Remove the ventilation duct and cover (see Bentley's 640-12, figure 25). Set the assembly aside. 4. Remove the radio. 5. Remove the OBC by pulling the lever at the left rear of the OBC towards you. The OBC will pull out from its connector (26 pin IDC) At this point, you have access to the OBC connector and its associated wiring. The wires of interest on the OBC connector are connected to pins 21 (black/white or black/white/yellow, my car was the latter) and 9 (red/yellow, direct from fuse f20). The Bentley calls out OBC pin 14 instead of 21. Do not believe the Bentley. It is wrong. Pin 20 is likely not connected, but if it were, it serves as a timer trigger for heating. But I digress. My car was built in 7/90. It doesn't have a sword, it has a resistor pack. It also has the newer HVAC control. I only paid attention to wiring diagrams EWD-125 to EWD-127. A cursory glance at the '93 wiring tells me that this procedure MAY work with the 1993. Now for the relay installation: 6. The OBC connector at the rear of the panel slides to the rightfor removal. 7. Cut the cable tie holding the OBC wire bundle to the green cover for the IDC connector. Take care to not cut any wires. 8. "vampire" a 15" or so wire (I used white) onto the pin 21 wire. Call this wire w7. 9. "vampire" a 15" or so wire (I used red) onto the pin 9 wire. Call this wire w8. 10. Find a power wire that's always on that has sufficient amp capacity (at least 15 amps). There are a number of candidates relatively nearby. Carefully connect this wire (call it w3) to the hot wire and run it to where w7 and w8 are. 11. You will see a 3 pin molex connector bundled with two 4 pin molex connectors mated with only one green wire connected to each. Disconnect the four conductor connectors. 12. One of these green wires goes to the blower switch, position 2. The other goes to the resistor pack. Ring 'em out. The latter should always have resistance on it relative to ground. Call this wire w5. The former will show open if the switch is in position 0. Call this wire w1. I used green wires for w1 and w5. 13. You should now have five wires, labeled (you did that, didn't you?) w1, w3, w5, w7 and w8. Grab the relay and figure what pins are which. The wire numbers that have been assigned correspond to the connector numbers on the relay. If you wish, sleeve them with heatshrink tubing of an appropriate diameter before connecting them to the relay. Solder them all into place. Ensure you haven't inadvertently bridged any connectors. Flow the solder! You don't want any cold solder joints here. Trim excess strands of wire away from each solder joint. Slide the heatshrink down flush to the relay and shrink it, if you used heatshrink. You now should have the parked car ventilation feature in place, once things are reconnected. 14. Reassemble the OBC IDC connector and its cover with a new cable tie. The "junction" part of the cable tie should be on the same side as the socket side of the connector. 15. Slide the OBC connector back into place. Ensure that it "clicks" into place. 16. Ensure that the OBC removal lever is set fully towards the outside of the dash. Slide the OBC into place. If you feel anything but mild resistance, DO NOT FORCE THE OBC INTO PLACE. Check out why its not going into place. At this point, you can test the installation. Reconnect the negative battery cable. Turn the ignition to position 1. Press the OBC timer button. You should see "VENT" on the OBC display. If you press the "S/R" button at this point, the two LEDs on the timer button should flash and the fan should come on. If you press "S/R" again, the fan should come off. The OBC display will change to "VENT on" and "VENT off" on the button presses. Turn the key to position 2. You should be able to operate the fan normally with the fan switch. Turn the switch to position 0 and then to position 1. Press the OBC timer button twice. You should see something like "00.00amT1" on the OBC display. Enter a time using the "powers of ten" buttons. "S/R" should set the time and the left timer LED should illuminate. Hitting timer again will bring up the t2 display, which is programmed similarly. "S/R", after a timer has been programmed, toggles its state (eg. if it's enabled---LED lit---and "S/R" is pressed, the timer is disabled). The timer turn-on time is not affected by the disable. When you're done, disconnect the negative terminal of the battery. If the above doesn't work as stated, you've got a problem. It is very likely a wiring mistake. Disconnect the negative terminal of the battery, if you have not done so. Go through the instructions again, checking your work. Check fuses, especially f20 and the fuse for the wire you tapped for the other "always-on" 12v. Check that the relay contacts are not touching each other or something else. Be meticulous. Be patient. If you get frustrated, walk away from it and do something else. Have someone else check your work. You'll eventually find out what's wrong. So you've tested things and you're satisfied it works. Time to button things up: 17. Replace the radio. 18. Replace the ventilation duct. 19. Replace the glove box top cover. Ensure that you reconnect the switch and the light. 20. Replace the glovebox. Enjoy. Notes from Janis S: I would like to add some comments about this article that can make life easier for another people trying to repeat the procedure described above. 1. I used standard automotive 12V 30A relay, which has different pin numbers. So in my case they were: w1 - 87a w3 - 87 w5 - 30 w7 - 85 w8 - 86 2. There is no need to remove radio and OBC, you can use the original BMW park heating/ventilation relay box connector to connect wires w7 and w8. This is an unused 8-pin connector (shown in the picture) hidden somewhere near to OBC. Connect red/yellow wire to w8 and black/white/yellow wire to w7. 3. "Always on" power w3 can also be taken from the same red/yellow wire, it is protected by 30A fuse that is more than enough for blower, so wires w8 and w3 can be connected together.