91-94 ecu, wiring harness in 1990 gsx

[snamtrac]

I just got a 1990 gsx and I swapped in a 91-94 engine harness and ecu. I am dropping in a 6 bolt with 91-94 tb, cas, etc. I was wondering on the passenger side there is a white plug for the interior harness and it does not match my 91-94 engine harness. There are 2 additional wires, but I am unsure if these are needed? I have the original engine harness that was in the car with that plug, so could I rewire it?

I tried searching, but didn't really find info about this particular plug.

Thanks.

 

[snamtrac]

I attached a picture of the white plug I was talking about. I circled them on the passenger side of the dash.

Thanks.

 

[ilco187]

what, i can barely see that if there was a up close shot of what you mean, from what i can see the plugs are for the door harness, but i can barely see that.

 

[snamtrac]

Here is an updated photo

 

[SBstar]

On the passenger side wiring harness part you can trim the plug to connect into your 90 plug. If you inspect it closely you'll see everything lines up other then extra plastic on the 91 plug, trim it off and plug it in.

Under the dash you'll need to color match the wires, you'll end up with a few extra wires from the 91-94 harness, that's ok, the car will still run fine.

I did the same thing by swapping wiring harness/ecu in my 90, trust me it works and I have a running car to prove it. Unfortunately my only glitch so far is a non-working tachometer. Everything I've read says swapping a 91-94 tach in is the way to fix it, unfortunately that hasn't worked either. Please let me know if you have the same problem as I'm trying to figure out if the problem is related to the wiring harness swap or another issue.