87/89 wiring harness swap
Thread Starter
5th Gear
Joined: Jun 2007
Posts: 5
Likes: 0
From: Perth Western Australia
87/89 wiring harness swap
Hey all. My 87 was bought with a smashed front end. I already have a 89 half cut, and as the 87 wiring loom was messed up and it was running a carby (dont know why), i am swapping the 89 engine, trans, diff, front wiring harness and computer (89). Having some trouble with some connectors that are different between the years. Has anyone done this? Will it just plug and play, or am i dreaming? Both cars were bought in pieces, and its my first vette. What can i say, i love a challenge.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
It's plug and play as long as you use the '89 harness with the '89 motor and ECM. '89 eliminated the Cold Start Injector and routes a couple of ground wires a little differently. Suggest you obtain the '89 body schematics which are at the end of the Shop Manual along with the Electrical update - all is included with the Manual. There will be one or two wires left over, as the '89 harness was also prepared for the ZR1, even though it didn't make it into production. The Body schematics identify those wires (as LT5) - basically to an unused/uninstalled fuel pump relay and then at the pump.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
harness
I would lay out a harness diagram that you draw yourself as you go along, and splice the wires together. Mark where every splice is.
Use an aircraft wire crimper, and aircraft wire splices. Those are good for about 20 years if done right.
I would use the original car harness and splice in the proper wires from the 89 harness to maintain the wire colors and tracers.
In 89, they changed all of the wire terminals, relays, and connectors.
If you keep your car all original, even though it was repaired, it would still be worth more when you go to sell it.
That way, you wouldn't have to chantge anything and re-engineer it.
If yoiu use the 89 computer, just use your original chip, and keep going.
If your connectors are smashed, I suggest you use the 89 in limited fashion, and keep what you can original for conformity.
But that's just me.
Splicing in odd color wires just make everything more difficult when you or others are trying to figure out why a system quit.
Use an aircraft wire crimper, and aircraft wire splices. Those are good for about 20 years if done right.
I would use the original car harness and splice in the proper wires from the 89 harness to maintain the wire colors and tracers.
In 89, they changed all of the wire terminals, relays, and connectors.
If you keep your car all original, even though it was repaired, it would still be worth more when you go to sell it.
That way, you wouldn't have to chantge anything and re-engineer it.
If yoiu use the 89 computer, just use your original chip, and keep going.
If your connectors are smashed, I suggest you use the 89 in limited fashion, and keep what you can original for conformity.
But that's just me.
Splicing in odd color wires just make everything more difficult when you or others are trying to figure out why a system quit.
Melting Slicks
Joined: Mar 2004
Posts: 2,141
Likes: 2
From: Pittsburgh Pa
I would lay out a harness diagram that you draw yourself as you go along, and splice the wires together. Mark where every splice is.
Use an aircraft wire crimper, and aircraft wire splices. Those are good for about 20 years if done right.
I would use the original car harness and splice in the proper wires from the 89 harness to maintain the wire colors and tracers.
In 89, they changed all of the wire terminals, relays, and connectors.
If you keep your car all original, even though it was repaired, it would still be worth more when you go to sell it.
That way, you wouldn't have to chantge anything and re-engineer it.
If yoiu use the 89 computer, just use your original chip, and keep going.
If your connectors are smashed, I suggest you use the 89 in limited fashion, and keep what you can original for conformity.
But that's just me.
Splicing in odd color wires just make everything more difficult when you or others are trying to figure out why a system quit.
Use an aircraft wire crimper, and aircraft wire splices. Those are good for about 20 years if done right.
I would use the original car harness and splice in the proper wires from the 89 harness to maintain the wire colors and tracers.
In 89, they changed all of the wire terminals, relays, and connectors.
If you keep your car all original, even though it was repaired, it would still be worth more when you go to sell it.
That way, you wouldn't have to chantge anything and re-engineer it.
If yoiu use the 89 computer, just use your original chip, and keep going.
If your connectors are smashed, I suggest you use the 89 in limited fashion, and keep what you can original for conformity.
But that's just me.
Splicing in odd color wires just make everything more difficult when you or others are trying to figure out why a system quit.
Thread Starter
5th Gear
Joined: Jun 2007
Posts: 5
Likes: 0
From: Perth Western Australia
Thanks for that. Wheels, factory or aftermarket?
Hey guys, thanks for the info. Need to source some new wheels, the 89 front and rear have different offset to the 87. What looks best on C4 light blue convertible. Thoughts, factory or aftermarket..
Last edited by StevoK; Sep 3, 2007 at 08:13 PM.
