Wiring question

[Jean]

I tried to find a concise answer in the "The comprehensive DOHC engine swap thread. " here on the forum but to put it simply didn't.

When doing an M50 swap into an E30 do you have to use part of the e36 engine harness (in the engine bay) and keep the e30 harness as the other half (in the dash etc) and it works with the e30 cluster ? How will the e36 wiring connect with the e30 wiring or am I totally off base here and you have to create a custom wiring from ground up ?

I am trying to understand how it works together and exactly what it takes to get m50 or m52 working in e30 chassis / cluster ?

[Lobstrosity]

You need to splice the e36 engine harness into the e30 body harness. On 325i's, there is a circular connector at the fuse box that people make an adapter for to do this rearranging of wires, but I believe (never looked, myself) earlier e30s did not have this circular connector, so you need to do some soldering. Just match up the appropriate wires using bentley manuals, and you'll see what has to be done. I think there's also a copy of the e36 wiring list on here somewhere, so you don't need the e36 bentley.

[Jean]

Is it not possible to just use a full e36 harness or will not match up with the e30 cluster ?

[Lobstrosity]

Is it not possible to just use a full e36 harness or will not match up with the e30 cluster ?

Use a full e36 body harness? That contains a lot more stuff than just the cluster connection. Stripping out the unused portions is just as time consuming as just wiring it into your e30 harness.

I highly doubt the e36 cluster has the same connector as the e30. However I could be wrong, some things never change. :)

You could also get the body-side circular connector from the e36 body harness, and wire that into your existing e30 wiring, then just plug the e36 engine harness in cleanly.

[Mike B.]

Why would you want to rewire the chassis side of the E30???

All of the existing wiring works with the swap, just match pin #'s.

[Jean]

If the early e30 does not have the round plug how else would you go about doing it, other than splicing the wires ? Seems half-assed to me and that's why I asked how people are doing this task...

[FredK]

When you use an adapter, it's actually using four connectors:

1. E36 harness connector
2. E36 x20 connector harvested from E36
3. E30 C101 connector harvested from E30 harness
4. E30 body side connector that is connected to E30 fuse box

For late model cars, parts 3 and 4 are circular. For early model cars, 3 and 4 are rectangular.

[eko]

The early E30 does have the round connector(C101).
Just chop the connector off the old E30 engine loom leaving around 8-10in of excess wire.
Chop off the connector on the M50 engine loom leaving as much of the wiring still on the loom as possible,match by pin nuber,solder and heatshrink each wire!
Then simply plug the M50 into the E30 loom.

If you are doing this to an early model theres a couple of wires from the M50 that will need running direct inside the car,seem to remember that one is for the tacho(rev counter) one is for engine management light(not really needed) and cant remember the last one.

Hope this helps!

[Cooper]

The early E30 does have the round connector(C101).

My pos 85e sure doesn't..

[BCM]

Is the DME/Computer from the engine you're swapping in considered part of the Engine harness, or are you still using the E30 DME? I suspect the former, just want to be sure myself.

Thanks.

[Mike B.]

BCM, you need to use the E36 DME.

[BeirBrennerE30]

you use the e36 engine harness with e36 DME as a unit... there is one one point of connection between the e30 wiring and the e36 wiring and that is the plug next to the fuse box(round or square)...

all you have to do is to match wires by function from the e30 side(the body wiring harness that came in the car) to the e36 side( the harness that came on yoru engine)... the only part of the e36 engine harness that goes into the actual cabin of teh car is the connector for the DME in wich it only connects to the dme and nothing else thats part of the car

do NOT directly connect with a permanent connection the e30 body harness to the e36 engine harness... if you ever need to remove the engine again you will be screwed