Ok, so here is the situation. I just picked up a 93 G20. It has had the motor and trans from a 95 G20T put into it. They were basically set in. I had to hook up the motor mounts, exhaust, CV shafts, etc. It also came with two ECUs. I beleive that the wiring harness is also from the 95. The plug near the ECU that goes into the dash wont plug in. So I also have another harness that isnt installed. The plug near the ECU clips right into the harness leading into the dash. Should I switch wiring harnesses? Or do I need to cut the plugs off and reconnect them by color matching? I ask this because when I hook up the car to a battery or jump pack, I get no power at all. The door doesnt ding, no dome light, no windows, fuel pump doesnt run. Is there a main fuse or relay for power to everything? Maybe a ground I am overlooking? On the 95 G20 I could hook up a jump pack and the dome light came on, seats moved, windows worked and such. This was with the motor and trans gone and also the harness gone. Is there something unhooked or blown on the 93? LOL I need help! Its a nice daily driver I just need to make it run.

I take it you're using a '93 dash harness with a '95 engine harness? That won't work, the '95 has a different setup because of OBDII.

ok, so will the 93 engine harness plug into the 95 engine and sensors ? or should i swap everything out to the 93 sensors and stuff? lol i guess i will find out soon

The '95 engine is set up for OBDII, the '93 is OBDI, so using the '93 harness won't work either. Either convert the '95 engine to OBDI or use a '95 dash harness. Neither is going to be much fun to do, but they're not impossible tasks, either.

ok, so i am picking up the entire obd 1 engine tonight. what do i need to swap over to make the 95 motor compatable with the 93 harness? i plan to just go through and swap over anything that doesnt plug in, correct?

could this also be part of the reason that I have no power to the cabin? when I tested the battery leads they were good and I had continuity.

I honestly don't know exactly what you'll have to change over. I know there's an extra oxygen sensor in OBDII cars, and I think OBDI SR's don't have EGR, but beyond that I'm not sure. Replacing whatever doesn't plug in is probably the simplest way to find out.

The cabin electrics probably changed in 94 or 95 as well, so that idea makes sense as well.

i got the power working into the cabin. i had a bad ground lol. but everything else seems to fit pretty well.

i think that the same wires and signals are coming from the ECU and into the dash, just in a different style plug. It seems like they are all the same color and location, so I am going to cut off the plugs and switch them. luckily, the 93 came with a factory service manual and supplement in the trunk

I have covered this a dozen times. You can use highport sr's in oem lowport cars and vice versa. As long as you use your wiring harness and ecu you won't have any issues. the only issue I have seen is that you will have to extend the knock sensor wire if you put a highport sr into a lowport car. So in your case, use the ecu that originally came with your car and the wiring harness as well. Everything else plugs up just as it did with the old motor.

the harness for the 93 didnt plug into the newer motor. the distributor plug and some others were very different. instead i used the 95 harness and ecu and just switched plugs on the area where it plugs in behind the dash. started up and everything seems to work. the trunk solenoid doesnt seems to work though and the lock cylinder is frozen solid lol. i guess im going in through the back seat

you are right, the obdII cars have internal coils. all you had to do was switch distributors. very easy fix and didn't require switching harness or ecu's.