OBC retrofit woes: Pls Advise.

[emw525E34]

So, I got a German OBC from an indepedent, the OBC was working and was tested it on an E32. There I was excited to retrofit this gizmo and when I remote the clock, the 26pin connector in my car had only 3 wires connected to it!!!. What happended to the rest ?. Where can I find the rest of the needed wires that are supposed to come from the main wiring harness ?. Pls help.

Car is E34 Touring 95 Euro model with manual tranny. NO sunroof :( but the rest works very well.

[ukm5]

almost all places that mention the retrofitting of the obc they mention to check your plug, as not all cars were fitted with the extended version when they had the standard clock.

you should have checked before buying!

its far too difficult to do this if you only have the 3 wire harness

[emw525E34]

Are you sure it is too difficult ?. I can splice wires from the instrument cluster and also the ECU , if I have to. I am getting this to work regardless of the challenge. All I needed was about 16 wires to complete the functionality I wanted. Don't need gong interface 2 wires, dont need telephone int, code function.

I have the CheckControl module and the instrument cluster display seems to display all warning messages correctly. Just needed the rx/tx lines to the OBC plus the right power/switch/ground wires. Also, fuel sender input, maybe an ECU pin or two. I got the full wiring diagram and wire codes in a printout.
I am trying to determine if anyone has looked at the jumble of wiring mess below the driverside to see if there is one bundle I can splice from. Would hate to splice from too many different places.

I have a E34 sedan to double check the wiring codes as it had a full 26 wire compliment to its OBC. I just do not want to take the dash apart!.

PS: The harder a problem it is for the E34, the more I want to solve it. Having spliced a piggyback to the intake and a boost controller to the ECU before, I would not think it would be so difficult, just time consuming and ackward position of those wires.
Who knows ?, I might get lucky to find a X501 connector in there, that is short!.

[Kalevera]

Probably have to replace one, if not multiple, wiring harnesses in the dash to get it to work. I would think the splicing and dicing game would be hazardous for this application -- lots of wires, lots of connections = just asking for a large fire...

...what the heck, I'll post it again (he he he):

http://www.bimmer.info/bmw/lowell/bmw1.jpg

Don't want that happening ;)

I know the feeling of needing to do it, if not just to prove it to oneself that it can be done -- and I'd consider doing it if I were in your position. In which case, you'll want to PM Javier and get the scoop on the electrical nightmare that is about to ensue.

best, whit

[emw525E34]

Thanks for your insight, Whit. Javier gave me the wiring diagram before already. I had a russian E32 wiring diagram that is useful and wiring codes co-relate to it. I think less than 20 wires is no big deal. I am cautious splicing. I solder and heatshrink wrap the joints. Then space then about 3 mm apart, then heat clue them in a row (with plastic base) and label them. This way its easy to see if there are shorts later, maybe even put a fuse or two in series with the power lines. It might be easier to wire these to the ECU compartment end as I have done in my other car, I will check the wiring mess below the driver side first to see what wires I can use.
Electrical fires are diasterous, and I shall avoid them at all costs. Got a portable fire extinsguisher below the driver seat for such things already!.

[ukm5]

Thanks for your insight, Whit. Javier gave me the wiring diagram before already. I had a russian E32 wiring diagram that is useful and wiring codes co-relate to it. I think less than 20 wires is no big deal. I am cautious splicing. I solder and heatshrink wrap the joints. Then space then about 3 mm apart, then heat clue them in a row (with plastic base) and label them. This way its easy to see if there are shorts later, maybe even put a fuse or two in series with the power lines. It might be easier to wire these to the ECU compartment end as I have done in my other car, I will check the wiring mess below the driver side first to see what wires I can use.
Electrical fires are diasterous, and I shall avoid them at all costs. Got a portable fire extinsguisher below the driver seat for such things already!.

well im an electrician and I have alsorts added to my car, sat nav, computer in the boot, fridges, boot flourescent lighting etc and I wouldnt even attempt to patch in an obc you have to much scope to f**k some other system up, and saying you have a fire extinguisher is nonsense, as for one thing its not much use with a fire behind the dash or anywhere else for that matter, wires are always hidden so how do you extinguish them. Not to mention that youre not in the car 100% of the time! just because you can soilder and splice and the fact its 'only' 20 wires does not make this feasable. Obviously anything is possible given the time, but the scope for mistakes and problems really isnt worth it

[emw525E34]

Well, I will give it a buzz soon , no worries. Here is my track record:
On my other E34 sedan:
- Patch APEXI Super AFC to ECU. 14 wires soldered. Patched. dragged into cabin via aircond conduit.
- Patched IN2 O2 sensor pin from ECU in-O2 pin into the Apexi, so I can "see" my O2 readings while I tune the 535AFM.
- Patch APEXI AVC-R Elextronic boost controller. 12 pins in ECU spliced, soldered and dragged into cabin mounted on ashtry area. This meter shows me Injector duty cycle across time, realtime graph.

My car was doing serious track days for 2 years almost monthly. Not a single problem. So if anyone thinks a simple OBC is going to turn me away, dream on!.

[Javier]

that may help you find the wires you need to tap (by locating the plugs and connections involved, Russian version should have it), guess you won't be lucky enough to get all the tap points from the same harness. Not sure USA drawings will be precise, but may help, let me know if I can assist you with them. You may also need to obtain some extra devices, like the temp. probe located in the front bumper for exterior temperature reading. Also the left hand lever (stalk) has to include the push contact to activate the OBC reading in the dash (may be there already), and the coding plug in the cluster should be available at the wiring, as OBC will attempt to read it and will display PPPP if fail to do so.

Good luck, and let us all know about your results, I'm sure this project will bring more knowledge to the community.

Javier

[Dan in NZ]

If the gong is disconnected, "CHECK CONTROL" is displayed in the instrument cluster, so you probably would have to wire that in.

It would be worth checking that the instrument cluster is compatible first, there was a simpler version of the inst cluster that does not support the OBC.

I did the OBC retrofit myself, and fortunately I had the full harness, but it still needed a few tweaks to get it working properly. It was a bit of a challenge to find where the manufacturer hid the outside temp sensor, and I had to supply +12v to some pin since I didn't have the alarm horn. I also had problems with the inst cluster display showing garbage until the indicator was re-wired. After all that, I wouldn't even try if the car didn't have the full harness!!!

Good luck!

[emw525E34]

Thanks Javier for the diagrams. Those will certainly be my main guide posts to figuring out this wiring mess. I might want to extend some other features if I find something there I can use. But first task is to get the core functionality I needed, then see what else can be extended.

I got a knack for things electrical or electronic... When I was 13, my older brother axed his radio tape recorder. Actually split the darn thing into two halfs. Guess what ?, I got the radio half and within 3 days it was a working radio and it was mine!.
PS: Anyone attended Bent2005 event in NYC at The Tank ?.