I have a 90 gxl with a bad engine(no compression on back rotor). I bought a jspec engine complete with wiring harness and ECU. While examining the jspec motor, I noticed that it has one less group of connectors that connect inside the car. Both the aspec and jspec wiring harnesses have 3 yellow connectors , but the aspec connector has another "goldish" colored connector. I can see the golden one connects behind the plastic panel in the passenger compartment, but what is it for? Will I need to splice wires on the jspec harness and connect it to the golden receptacle? Or can/would be better off using my orignal harness on the jspec engine...... Thanks.

Yes, the jspec engine is an S5.

 

You should be using the US-spec harness and ECU.

 

The jspec harness will barely reach to the US ecu location, you have to do some rearranging of wires and pulling on the harness, neither of which is a good thing. Also, that gang plug the jspec harness is missing plugs in under the dash, adn runs such creature comforts for a streetcar as wipers, cruise control, heat/ac blower motor, dash temperature gauge, etc. The jspec harness will run the engine properly, however, if that's all you want to accomplish.

You need a north american spec 89-91 turbo harness. Or, modify your existing 89-91 nonturbo harness, which is quite easy to do...lay it out over the new engine, decide which (if any) sensor wires need relocation, and modify them. I beleive the knock sensor wire is the only issue, and one of the NA's VDI solenoid wires gets used for this (check ecu pinout maps and find out which one to use).

 

Thanks Kevin!!! I'll go ahead and reuse my NA harness.