Early model harness wiring chart

[Kerrath]

I've been looking for weeks, maybe months for complete wiring for an E34 M50 n/v from a 1991 to a 1986 325e. I know there's the business of the C104, and don't entirely understand that, but besides that it seems like there are a TON of wires that don't go anywhere. Using a couple charts, I pieced together that there are a lot of wires that should be used, but I dont have anywhere to put them.

I made up this chart using what information I do have.
All the filled in things in the category "E34 to E30" are ones I know to be correct. The blanks are E34 wires that don't yet go anywhere. I'm hoping somebody might be able to help me fill those in better. On the far right, those are the pins that look to be on my E30 side harness, though the spacing is so tight, anything above Pin 12 might be shifted one over.

There's not a lot of information for swaps into early models that I can find, and if I can get my chart complete, I'll fill it in and post it for anyone else who needs it like I do.

[lifeiskaos]

LOL. sorry my adapter wasnt good enough for you... car runs right? who needs extra's? silly things like tach's and temp gauges.

seriously though. i've been helping craig search forever and no one seems to give specific wiring instructions for early model dohc swaps. can someone help us out?

[mongule]

Damn, I'm away at school so my wiring diagrams are at my parents.

I have an 87is but the wiring is similar to an 86


But maybe I can help you out form memory here.

The C104 is in the glove compartment near the ecu.
Its a 3 wire connector.

One wire is for fuel consumption/economy
And one is the signal for the tach.
There is another wire that we dont use.

Sorry I can't help with colors as they might be different, but for me the tach signal was the black wire. And I'm not sure on which color the other one was but I beleive it was white/yellow.

For speed signal to dme I needed to splice into one of the plugs in the back of the cluster and run that wire to the dme directly .

Maybe you could run that wire to pin 14 on the e34 harness side.
I'm not sure about this so you should check the etm.

Not having the wire connected gave me a revlimit at 5200 rpm..
But I have an OBD2 dme so it might not give you these problems.

The plug you have to splice in the back of the cluter is one of the two plugs that are situated where the speedo is. Look at the back of the cluster and you will see them.

For the tach and fuel rate wires i just pulled the wires out of the e36 well in your case e34 harness and brought them to the glove compartment.

Hope this helps,

If you need me to clarify on things let me know.

[mongule]

Also there will be alot of wires not used in the e34 harness.

[So Live]

Great thread. My buddy is doing an 87i and ill be helping him wire it up im sure. I wonder how different the harness' are...

Keep it going!!!

[mongule]

Any specific questions?

[Kerrath]

That handles engine speed and fuel consumption rate.
I assume the ABS has wiring outside of the harness to its computer, but I'd like to be sure of that. I guess the O2 sensor only goes to the ECU so it wouldn't make much sense for to go bodyside, but one of the charts I was looking at for a 1991 said it went through the bodyside, so I'm not sure about that either.

It looks like I left out the oil level static, I'm pretty sure that's 16->2 so unless that's wrong ignore that blank.

So that still leaves Check Engine Light Control, Speedo to OBC, Starter (I assume this is not signal, just a sensor), maybe O2 sensor and maybe ABS.

There's also supposed to be some modification for the coolant gauge. I believe you need the 1 pin sensor from an M20 and that pin gets split to two wires or something like that?


Thanks mongule, nobody as far as I remember has given specifically yellow/white so I wasn't sure if my C104 was colored the same as most others' and it would be a pita to have wired it up wrong. So black=tach yellow=fuel rate and green=whatever?

[mongule]

Yea thats how it was for me, and if i recall correctly the green wire that we dont use was a bit thicker (but i may be wrong)

I really should of typed my wiring diagram on the PC.

I can't help you on the abs, I took it out.

Dont worry about the 02 sensors, they are self contained in the e34/e36 harness.

Check engine will be different for me and you as we have different dme, but either way I havent got mine to work yet.


For the speedo to OBC, I'm not sure someone else should chime in on this, but this is where you have to splice into the back of the instrument cluster. The early models didnt have the speed reference going through the C101. I HAD to do this as I had an early fuel cut, but I'm not sure how it will for behave OBD1.


For the temp sensor, you need to put another temp sensor in the block, so you will have 2. Well thats how I have mine setup. run a wire from the m20 temp sensor to pin 4 on the c101. You leave the other one there.

Have you used the ETMs?

[Kerrath]

Used the ETMs, no. Looked at, yes. I can't read the wiring charts well enough to understand where to splice and connect wires. If I could actually use those, I wouldn't be asking. :(

[Kerrath]

I could use a bit more help.
Still have the Check Engine Light (or not) to figure out and the Speedo->OBC (ground speed?) and ABS to make certain of.

Thanks mongule for what you've had to offer so far.

[mongule]

Ok so i checked it out for your speedo to OBC,

This does the same thing on OBD1's.

You need to splice in the back of the cluster and run a wire to pin 14


And for ABS, it looks to be self contained on our early models nothing seems to go to the dme so I think your good on that.

Also i just noticed you have at 18>7...it should be 18>18

If its possible, could you peel the shielding on both connectors and tell me the colors of each pin?

I can look through the etm it will take like 5 minutes if you give me the colors that correspond to each pin.

[mongule]

Also pin 15 to 15 is wrong i just noticed that you don't have any pin on the e30 side,

How did you get starter for pin 15?

[Kerrath]

Ehhh, a lot of that information came from a chart for a 1991 that So Live used for his swap. I've been doing my best to convert the accessories for an early model because that's really all I've got left since the engine starts and runs fine.

[mongule]

Oh ok then.

Well i'm pretty sure you got all the info you need then except which exact wire is the check engine light in the cluster.

[Kerrath]

I dont know where on the back of the cluster I need to splice that wire in. everything else falls into place enough besides that though.