Will 87 Iroc harness work in 89 GTA
I purchased a 89 Gta with no engine no trans. I recently bought a 87 Iroc. THen took the engine and trans with harness and computer out of the iroc. everything thing is in but the iroc harness has an additional plug with 2 pnk/blk 1 tan/white besides the 15 pin plug .

Any help????

 

The only difference in the wiring harness is the cold start injector. This was eliminated with the 89 prom, so you'd have an extra injector plug originating from the harness as well as one that went to a sensor in the front of the intake if you were using the 89 harness. However, you say that you took the engine, trans, harness, and computer from the iroc so I have no idea why you're having problems.

 

Off the top of my head. . . pink/black wires are powered 12v with the key on. Tan/Wht is fuel pump signal but connects in about three places in the harness to the fuel pump relay and MAF power relay, I believe.

Your biggest problem is going to be that the '89 uses an electronic speedo and the '87 is cable driven. You're going to have to use the electronic speedo signal generator and wire it to the '89 speed buffer somehow.

Another is that, the '87 has a single fan relay, (I think) and the '89 has dual. No problem actually, double the relays at the firewall and use the same signal or go with an aftermarket fan switch.

Batteries may have been on different sides, (not sure) but that's not really a problem.

How are you set for diagrams? I have some scans I've collected and could zip them up. They are for 5.0 I think but wire colors and connector numbers usually apply.

 

EVERYTHING ON THE ENGINE WENT GREAT ITS JUST THE PLUG INS FROM THE 89 FUSE/ADL. ONE HAS 7 PINS THE OTHER HAS EIGHT. BUT CANT FIND WIRING SCHEMATICS FOR THIS. I KNOW ON 89 GTA THE INJECTOR WIRES CAME FROM THE FUSE PANEL BUT THE IROC CAME WITH A PLUG THAT HAD 2 PNK/BLK AND 1 TN/WH DO I JUST SPLICE IN THEN.

 

Go to the following site. Follow the links and I think you'll find the schematics you need for TPI harnesses. http://www.diy-efi.org/gmecm[/URL]

 

I just put an 87 TA harness in my 88 Camaro, and there is a ot of differences. I'm sure you're going to have even more headaches. I used a shop manual's schematics and did OK. I still need to hook up my AC signal wire to the ECM, but I've been being lazy.