the short story, I got an 87 Formula, I had a 90, I did a swap from the 90 to the 87. I swapped the engine, cooling, all interior including dash.

Before the swap when I bought the 87 it already had the electrical problems, after the swap and going through the harness during the dash swap the problems are still there.

Here are the problems. Left turn signal works, right signal works but it blinks slower, brake lights work, headlights turn on but do not go up. The old dash had a toggle switch put in by previous owner to make the lights go up, and it worked, so I know the motors work. Since I put in the 90 dash I took out the toggle switch, so not they just turn on but don't go up. When the headlights are on the left turn signal works, but not the right. The dimmer works and I can see the lights on the dash going brighter and dimmer, but the dome light doesn't come on, the rear latch doesn't open when I press the dash button and the radio doesn't come on at all.

Now at first I thought there was some bad wiring, but other than that toggle switch being in there the wiring looks perfect under the dash and under the rest of the interior. Also when i put the 90 dash in I forgot to hook up one wire, the ground near the fuse block. When that ground wire wasn't connected the electrical things were even worse. More odd, more things not working and working different than they should when the headlights were on. So after I hooked up the ground wire I saw things were back to the way they were before the swap.

So, my question, is there another ground wire(s) I should check for to make sure they are grounded properly so all the rest of the stuff will work right? Is there anything else I should check? Has anyone else had this happen before?

 

I do not own a bird but have trans-planted 91 GTA wiring harnesses into an 87 so, I'll take a shot and ask a couple of questions;

Did you transplant the complete interior wiring harness or just the dash plastic?

If you replaced the interior harness with the dash swap, Did you replace the wiring harness that ties the headlights and turns to the bulk head connector?
Also, assuming you replaced the interior harness, did you need to modify the connector to the rear brake lights and hatch?

 

No none of the wiring got swapped. And the problems were there before I swapped anything at all. The only wiring I modified afterwards was for the dash switches for the defrost and rear hatch, but the hatch didn't pop before the swap anyway.