Wiring harness - not sure where to start

[RenaissanceMan]

Converting my E30 M50 OBD1 car to an S52 running OBD2 and am at the point where I need to figure out the harness. I have searched through the different wiring harness threads and to be honest I am a bit overwhelmed.

I have the harness that came with my S52. The donor car was an M Roadster, which I understand has a slightly different harness. Is there a DIY anywhere that outlines what I would have to do to modify mine? Will I be using any harness components from my current OBD1 setup or will I be starting over? I'm not really sure where to begin. Any help is very much appreciated!!! Thanks-

[sweet3]

How was your swap done originally? Is there an adapter or was the m50 harness modified to fit the c101 on the fusebox? Or was the fusebox c101 converted to the 25-pin x20?

If you send me your M roadster harness, I can modify it to be plug-and-play.
I can also make an adapter (Depending on how your m50 swap was done in the beginning).

[RenaissanceMan]

Do these pics help determine? 1st is of the harness connection and second is the testing port. If I need to unplug the harness and count pins I can. Thanks for the help!

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[kronus]

Looks like M50 harness X20 was re-ended to C101. You'll need either an adapter from OBD2 X20 to C101, or to re-end the OBD2 harness to C101.

[luckysnafu]

Be careful hacking up the m roadster harness. My engine and harness came from an m roadster and there are a few differences to look out for, most notably the following:

Fuel pump relay - you'll most likely have to wire in your own fuel pump relay as they are located under the dash in the Z3M cars

Check engine light - It's connected to the X6031 connector on the wiring harness. I didn't think I needed that connector for the swap and cut the whole thing off before realizing I needed a wire from it. Make sure you trace it and know where it is before cutting off that connector.

My wiring diagrams are linked in my sig, which should help you out since one is specific to the z3m. Good luck!

[RenaissanceMan]

thanks for the info provided so far!!!

[sweet3]

That does appear to have been converted to the c101. You could count the pins to make sure.
Luckysnafu is right, don't just go ahead and start hacking away. There are a few differences.
Let me know if you would like an adapter or if you would like to have the engine harness modified.

[RenaissanceMan]

That does appear to have been converted to the c101. You could count the pins to make sure.
Luckysnafu is right, don't just go ahead and start hacking away. There are a few differences.
Let me know if you would like an adapter or if you would like to have the engine harness modified.

How much does it cost to have the harness modified? I'm assuming that would make for a cleaner install than adding an extra adapter?

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[sweet3]

Yes it does make it a more cleaner swap. I modify them to fit into the e30 firewall covers.
I only charge $175 to rewire the harnesses. (That includes return shipping)

[RenaissanceMan]

Ok, got some more clarification on my setup from the guy I bought the car from. He had cut off the body side harness connector and bought an e36 body connector and re-pinned it so that any M50 harness could be plugged into it. So evidently I dont need an adapter; I just need to thin my s52 harness and make sure the pin assignments match up. Make sense?

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[sweet3]

Oh okay. There are some changes that need to be made. Especially if you are using the m roadster harness.