91 engine harness in a 90

[jbeaton9292]

ok so i just have a few questions about this swap i have looked and read many threads about the swap but nothing that answers my questions fully.

well i have the 90 harness out of the car and im going to pick up the 91+ tomorrow. im just wondering what all needs to be changed, i know that the 16pin connector in the inside of the car that tucks over by the door is differant and needs swaped. im also aware the coil plug and the ptu plug is different so i can either swap the plugs or swap the coil and ptu correct? what else is different? i already have a 91 ecu in my car so i wont have to swap pins 6 and 14 at the ecu right?

if i want my tach to work im gonna have to swap the coil and ptu right?

i know i can just findout whats different when i get it in the car but i would much rather cut and solder things while its out of the car so i can do it in the warmth of my house!

last thing i wanna know what can be eliminated from my harness? im having my brother in law make me a harness using the old harness plugs (he likes to solder and said it would be fun). so im gonna let him hack away at the old harness and make a new one and i wanna have the harness tucked away as much as i can and not have random stuff around (eliminate confusion).

by the way im not changing the body or dash harness just engine bay idk if anything has to be rearranged on either of them harnesses to make this work i havent seen anything about that but cant hurt to ask.

 

[19Eclipse90]

These will require attention, some only if you are keeping related '90 components:
http://www.dsmtuners.com/forums/152709626-post5.html
http://www.dsmtuners.com/forums/152709664-post20.html
http://www.dsmtuners.com/forums/152709690-post34.html
http://www.dsmtuners.com/forums/152709696-post37.html
http://www.dsmtuners.com/forums/152709711-post43.html

For things that can be removed:
http://www.dsmtuners.com/forums/electrical-tech/473806-1g-wire-tuck-harness-delete-help.html
http://www.dsmtuners.com/forums/electrical-tech/471294-90-wire-tuck.html

No, you do not have to swap pins 6 and 14 if you change both the ECU and harness from '90 to '91+ or vice versa. For the tach, if you're swapping to a '91+ harness and ECU, you'll swap the PTU and coil to the later style anyways. But that alone won't make the tach work. In my experience, all you can do there is find a '91+ tach and swap it in to your cluster.

 

[jbeaton9292]

well i already put in a 91+ cluster as well so that should fix it then if i swap the coil and ptu

do the coil and ptu have to be swapped or can i swap the plug and use my current parts?

 

[19Eclipse90]

They don't have to be swapped, but it is a hell of a lot more work to reuse the '90 connectors on a '91+ harness for '90 components if all you need to do otherwise is swap the '91 components in. And I don't see the tach working if that is done.

 

[9091dsmtsi]

I see this thread is a few months old but i am doing a similar swap and wondered how you made out. My 90 is completely intact as far as harness and wiring but the body is not in great shape. bought a 91 with a good body but i stopped counting at 15 wire nuts under the dash. engine harness is trash and ecm has blown caps. I am in the middle of switching everything from the 90 to the 91. engine harness, engine bay harness and dash harness. a heads up on any hurdles you encountered would be awesome.