View Full Version : Need help identifying this 24v harness

08-10-2011, 01:10 PM
See pic -- for use in my s52 swap..

I hate electrical and wires baffle me. This harness came with my s52, only thing is I don't see a diagnostics port-- is this an obd 1 harness?



08-10-2011, 01:14 PM
Bigger pics would help. The big plug in the 2nd pic looks like the diag port.

El Gato Liso
08-10-2011, 01:18 PM
ya that big one in the second pic is diag. port.

i cut that off my hardness thinking it was for the automatic tranny computer.....since my m50 came from an auto............oops

08-10-2011, 01:25 PM
Thanks for the help guy sorry I was looking for a GM-style plug --

I'm still confused mostly about DME stuff -- stupid question but is a red label 413 compatible with this obd2 motor without a full conversion?

08-10-2011, 01:40 PM
Please post bigger pics of the harness, it still looks strange. There should be 3 relays on the fuse box side, and I only see one on the DME side.

The DME is almost fully compatible. The engine is fundamentally the same, just bigger displacement. The only catch is the injector size, so you'll need to get a conversion chip (I had one from Turner).

This is what the harness should look like:





08-10-2011, 01:51 PM
From photobucket -- sery may be huge lol



There is a triple relay set on the other side of the harness, 2 green 1 orange

Thanks for the DME info ya I'll get the 21.5# tune as long as it'll work

08-10-2011, 02:03 PM
Hard to say, I'm tempted to say it's an OBD2 but it still looks odd... can you post a pic of the coil harness? That will tell the tale.

The reason I'm asking is I don't see coil wiring but I also don't see the coil bar. On the OBD2 harness, the coil harness is separate, like so:


08-10-2011, 02:21 PM
Ok more pictures:

Are these the relays you're talking about? They're on the other side of my harness but it looks in your picture like they may have been moved from there


The coil portion-- looks like it's attached to me :s


Your harness looks like a lot less than mine too lol I'm guessing it's had a lot removed for the e30... I haven't touched this one yet

08-10-2011, 02:27 PM
That's the injector harness. It's an OBD2 harness unfortunately. I can now see the round plug for the coil harness by the DME connector.

The pic I posted is a generic M50 harness, that's how it should look.

08-10-2011, 02:29 PM
I also just dug this up, which has obviously been cut... I think I just need a new harness I'm no good with this lol


08-10-2011, 02:32 PM
Yeah, that's an OBD2 coil harness, with the plug chopped off for some bizarre reason.

Yeah get another harness. Keep those coils though.

08-10-2011, 02:33 PM
Lol ya I think that's my best bet thanks for the info

08-10-2011, 02:37 PM
You're welcome. What's your general plan of attack? There isn't much customizing that you need to do on this swap but there is some. If you get a harness adapter, you solve most of it. What's your plan for the temp sender, and tach signal? You know that you need OBD1 sensors right? (obd1 m50 cam, crank, temp for dme, m20 temp for cluster)

08-10-2011, 02:42 PM
Ya I have most of the swap plan of attack finalized -- with the exception of the wiring which I'm just starting to get into ...

Was planning on my m10 temp sensor, and treehouse adapter -- I actually didn't know about the obd1 sensors, I have the ZA conversion cd also that goes into some detail about harness modification but I haven't gotten my head around all the bits yet

08-10-2011, 03:12 PM
When you say ZA CD, do you mean the OBDII->I CD, or the 24v swap CD? The swap CD is good but they do a bit too much. The other problem with it is that they do an M50 swap, you're doing an S52. Overall the OBDI conversion is pretty trivial but none of the sensors are compatible. The S52 even has the trigger wheel at the front, and a bracket for the OBDI crank sensor, but you do need to buy one. The cam sensor is different too. The knock sensors won't work, same with the temp sensor for the engine. The S52 has a single sensor which sends the temp signal to the computer and cluster. So the head only has one sensor hole. You need to get a DME temp sensor for the one hole, and either drill/tap a hole for the cluster, or use the Zionsville temp manifold (good, clean solution).

08-10-2011, 03:22 PM
Oh hey you're talkin about doin the obd1 sheesh I thought you meant use obd1 sensors for an obd2 swap lol

Truth is I'm still on the fence about the obd1 conversion ... I'm planning on a build thread soon in which I'll raise the question more thoroughly

I just want the least electrical headache possible, but if obd1 isn't too bad then the conversion may be worth it...

08-10-2011, 03:39 PM
Well, my advance input is don't bother with OBD2. It's been done but the only reason I could think of for doing it is just for the challenge.

08-10-2011, 03:42 PM
ok -- last question:

If i was to go OBD1 -- any good place to source sensors from?

08-10-2011, 04:33 PM
ok -- last question:

If i was to go OBD1 -- any good place to source sensors from?

I would buy new. They're not that expensive from online US dealers (bma, fap99, blunt on r3v). These things go bad and the newest one you'll find used is probably gonna be 10-20 yrs old.

08-10-2011, 07:08 PM
I have an OBD2 ignition coil harness for sale. If you're interested send me an offer!

**Edit** Actually i'm pretty sure I have both the crank and cam sensors for OBD1 as well that are in working order if you decide to buy used.