Chassis/Engine Harness Help!

#1

I had to replace the entire chassis harness and engine in my '87 325is. I got a chassis harness from another 325is (automatic), but the engine harness is from an '89 325is (manual). I got everything buttoned up and installed, turned the key, and nothing. Then smoke starting rising from the relay box. The red/yellow wire going into the main relay is toasted. Any ideas?

#2

I had the same problem (smoke leaked out) when I put my '90 airbag motor/harness into an 89 non-airbag car.

I was told, not sure it’s true but sounds plausible that the engine harness was changed late in the 89 production run.

My solution was to use the harness that matched the body, and on swaps we’ve done in these parts since, we’ve tried to keep harnesses matching the basic vintage of the body, and haven’t had any further problems.

#3

Both cars were non-airbag cars, and I had an '87 harness, but it had 2 wires pulled out of the round plug and the injectors were no longer labeled, so I switched out the whole intake/harness in hopes of keeping it simple… no dice.

#4

To use a late harness in an early car (what you effectively have) one wire in C101 needs to be cut and a pigtail must be added to the harness at the DME connector for start and tach signals.

Cut the wire going to pin 20 of C101. Peel back the sleeving on the part of the harness that goes to the main relay and repair the damage. Make sure that the damage doesn’t go deeper into the harness. If it does you’ll want to get another harness.

The 87 body harness has a white three pin connector near the DME with wires:

Blue/Black - tach - DME pin 6
Green - Start Input - DME pin 27
White - Econometer - DME 32

Those signals are routed through C101 on later harnesses and so you have to add a pigtail to the late harness near the DME connector going to the pins listed above.

#5

D@mn Jim beat me to it, I was just going to post that same thing.

I think the harness has to match the year of the car per the rules so we’ll just add that to your protest sheet.

#6

jlevie wrote:

[quote]To use a late harness in an early car (what you effectively have) one wire in C101 needs to be cut and a pigtail must be added to the harness at the DME connector for start and tach signals.

Cut the wire going to pin 20 of C101. Peel back the sleeving on the part of the harness that goes to the main relay and repair the damage. Make sure that the damage doesn’t go deeper into the harness. If it does you’ll want to get another harness.

The 87 body harness has a white three pin connector near the DME with wires:

Blue/Black - tach - DME pin 6
Green - Start Input - DME pin 27
White - Econometer - DME 32

Those signals are routed through C101 on later harnesses and so you have to add a pigtail to the late harness near the DME connector going to the pins listed above.[/quote]

Thanks Jim! You don’t happen to have a diagram for the C101 connector do you…early and late? MAybe a link to one. I found a few, but most just say M20 and don’t specify early or late.

#7

uphkrsrcraz wrote:

[quote]jlevie wrote:

[quote]To use a late harness in an early car (what you effectively have) one wire in C101 needs to be cut and a pigtail must be added to the harness at the DME connector for start and tach signals.

Cut the wire going to pin 20 of C101. Peel back the sleeving on the part of the harness that goes to the main relay and repair the damage. Make sure that the damage doesn’t go deeper into the harness. If it does you’ll want to get another harness.

The 87 body harness has a white three pin connector near the DME with wires:

Blue/Black - tach - DME pin 6
Green - Start Input - DME pin 27
White - Econometer - DME 32

Those signals are routed through C101 on later harnesses and so you have to add a pigtail to the late harness near the DME connector going to the pins listed above.[/quote]

Thanks Jim! You don’t happen to have a diagram for the C101 connector do you…early and late? MAybe a link to one. I found a few, but most just say M20 and don’t specify early or late.[/quote]
Travis, I have the ETM’s on my hard drive for 1987 and 1989, which may help you. I can’t recall when I found them, but I’m uploading them to F3P now and will post the links when they finish. The files are about 15mb each.

Done.

http://www.factory3performance.com/product_info/ETM%20E30%201987.pdf

http://www.factory3performance.com/product_info/ETM%20E30%201989.pdf

Edit: I could have sworn these had the pinouts for the connectors, but now that I’ve gone and looked, I don’t see them. Maybe I’m just blind!

#8

uphkrsrcraz wrote:

[quote]
Thanks Jim! You don’t happen to have a diagram for the C101 connector do you…early and late? MAybe a link to one. I found a few, but most just say M20 and don’t specify early or late.[/quote]
I’ll type up what I’ve gleaned from the ETMs, ohming out harnesses, and other sources later this evening.

#9

OK. I got the engine harness from the car that the main harness came from and put it on. The pin # 20 in the 101 connector was fried as well, and I replaced it (through the fuse box and grounded). I also by-passed the auto trans relay (I think). The relay wasn’t there to jump pin #30 and # 87, but the wires were black and black/yellow. The car is still not getting juice to the starter/fuel pumps, etc. I think there is another switch of sorts for the auto trans, but I cut a lot of that stuff out when installing the new main harness. Anyone know if there is another switch, and if so, what the wire colors are? It’s an '87i auto trans wiring harness.

#10

Travis call me 706-339-4820, I may have an answer for you but its too hard to explain by typing.

#11

Done. Cranked right up today after Al spent 5mins looking at it. Thanks AL! There’s an anti-theft plug w/2 green wires that had to be looped…that and I cut the black wire from the ignition switch and ran it straight to the starter. Should make RA now.