91 Z28 wiring harness removal
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From: barnegat new jersey
Car: 91 Z28 ragtop, 88 SS monte
Engine: 305 TPI
Transmission: auto
91 Z28 wiring harness removal
i have a 91 z28 TPI car.the motor and trans are out and now i'm trying to get the wiring harness out of the car.i have it out up to the firewall on the driver side.it goes through the fire wall and under the dashbord.where can i disconnect it?????????
Re: 91 Z28 wiring harness removal
The C100 is the connector near the booster. Use a 1/4" socket on a 3" extension and it will come off
If you mean the dash harness, those are attached via allen keys from the inside. Id leave that one alone unless it must be removed as those allens love to strip out and you have to drill the firewall
If you mean the dash harness, those are attached via allen keys from the inside. Id leave that one alone unless it must be removed as those allens love to strip out and you have to drill the firewall
Thread Starter
Junior Member
iTrader: (2)
Joined: May 2008
Posts: 21
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From: barnegat new jersey
Car: 91 Z28 ragtop, 88 SS monte
Engine: 305 TPI
Transmission: auto
Re: 91 Z28 wiring harness removal
thank you.thank you.thank you.i can't believe i missed that.it was driving me up the wall.
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Joined: Mar 2008
Posts: 22
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Car: 92 Z28 B4C Edition
Engine: 5.7 TPI
Transmission: 5spd
Axle/Gears: Posi
Re: 91 Z28 wiring harness removal
[quote=Pocket;4286600]The C100 is the connector near the booster. Use a 1/4" socket on a 3" extension and it will come off quote]
Hey i had a question about the wiring harness removal also. I just recently found that screw that comes off with the 1/4'' socket which made my life sooo much ez'er
thank you bud. But now what i am having trouble with is how to remove that harness alltogether. I mean i have that screw off and the connector not connected but i am having trouble taking the wires off from the front of the car.
I can not get it out because of the rods in a X like shape where the radiator used to be. I have pics that i will put up later today but i just don't know how to get the wiring harness from the passanger side front head light to go across to the driver side front head light and the just come off to completly take off the harness from my car.(from the passanger side) The wiring harness has to go into this small little gap and over this big plastic thing that has plastic screws that i just can not take off with out wanting to cut them. Does anyone know how to take those off the right way?? 

If someone could help me i would really appriciate it, i just need that to be able to start getting my 5.7L TBI in the car. Thank you
Hey i had a question about the wiring harness removal also. I just recently found that screw that comes off with the 1/4'' socket which made my life sooo much ez'er
I can not get it out because of the rods in a X like shape where the radiator used to be. I have pics that i will put up later today but i just don't know how to get the wiring harness from the passanger side front head light to go across to the driver side front head light and the just come off to completly take off the harness from my car.(from the passanger side) The wiring harness has to go into this small little gap and over this big plastic thing that has plastic screws that i just can not take off with out wanting to cut them. Does anyone know how to take those off the right way?? 

If someone could help me i would really appriciate it, i just need that to be able to start getting my 5.7L TBI in the car. Thank you
Last edited by Bocklevon; Feb 9, 2010 at 11:04 AM. Reason: Type of Car i Have is a 91 Pontiac Firebird
Re: 91 Z28 wiring harness removal
The front light harness goes through the radiator support. It takes some finesse, but it will fit though those holes. You will have to remove the bulbs from the larger turn signal sockets to fit them. Start on the pass side and push it back though, the C100 side will never make it
You dont have to remove the light harness to change engines. Actually Im not sure why youd remove it at all, unless to repair, modify or sell it
You dont have to remove the light harness to change engines. Actually Im not sure why youd remove it at all, unless to repair, modify or sell it
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Joined: Mar 2008
Posts: 22
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Car: 92 Z28 B4C Edition
Engine: 5.7 TPI
Transmission: 5spd
Axle/Gears: Posi
Re: 91 Z28 wiring harness removal
I was going to remove it because the harness is originally from a 5.0L carburated engine, and the engine i want to drop in there is a 5.7L TBI, i do have to switch harnesses right? or i dont?
Last edited by Bocklevon; Feb 9, 2010 at 04:48 PM. Reason: carburated
Re: 91 Z28 wiring harness removal
The light harness has nothing to do with the engine harness. They each make up half of the C100, but thats it
The LO5 harness wont fit the 3rd gen, you must modify it or use a LO3 3rd gen harness
Assuming this is in your 91, you will not have a carb harness in there, its V6, TBI, or TPI. A carb swapped car will still retain some of whatever the original harness was
The LO5 harness wont fit the 3rd gen, you must modify it or use a LO3 3rd gen harness
Assuming this is in your 91, you will not have a carb harness in there, its V6, TBI, or TPI. A carb swapped car will still retain some of whatever the original harness was
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Joined: Mar 2008
Posts: 22
Likes: 0
Car: 92 Z28 B4C Edition
Engine: 5.7 TPI
Transmission: 5spd
Axle/Gears: Posi
Re: 91 Z28 wiring harness removal
Really? But the C100 is connected to the Front Light Harness. How do i take it apart? or do i keep the entire wiring harness from my old engine and reconnect it on my new engine? I mean 5.7L TPI not TBI sorry for that. You know what, i think i now see what you mean by it's both connected at the C100, i remember seeing two big connections their, so i'm gussing i just unplug it from there. Thank you sooo much Pocket. I am really greatfull for your help. If it would not have been that i almost got caught today by campus security making out with my girlfriend in the school's parking lot i would be really really happy. thank you.
Last edited by Bocklevon; Feb 9, 2010 at 05:28 PM.
Re: 91 Z28 wiring harness removal
The two halves snap together. Just look it over and youll see how it works
Remind me never to go to that campus. Busted for kissing? Out here as long as we're not getting it on in front of everyone, they leave people alone
Remind me never to go to that campus. Busted for kissing? Out here as long as we're not getting it on in front of everyone, they leave people alone
Junior Member
Joined: Mar 2008
Posts: 22
Likes: 0
Car: 92 Z28 B4C Edition
Engine: 5.7 TPI
Transmission: 5spd
Axle/Gears: Posi
Re: 91 Z28 wiring harness removal
lol it was Modesto's Junior College. But we were doing a little more then just kissing lol if you catch my drift. i was able to snap that pieace out and everything was all good but now the harness go into the passanger side of the car. Is their a way to dissconnect that also from outside or i have to do that from the inside? I tried to follow it inside but i kinda got lost. Is it that big square like connection at the bottom right side of the passenger's side foot? I can not express how gratefull i am for this help your giving me pocket, thank you soo much bro.
Re: 91 Z28 wiring harness removal
The light harness pulls from the pass front corner around the perimeter of the car. Its easier to pull it through from underneath
When I pull the engine harness I start at the passenger hush panel under the dash. Drop the ECM and unplug it along with the C207(clear connector dash side is two black halves). Next pull the retainer clip and push the pigtail back through the fender
Next, remove the pass inner fender well and pull the pigtail out and begin to push it up towards the HVAC box. Getting the fender grommet past the blower motor may take you a few minutes to figure out, but it does fit. I generally drape the harness over the engine until its ready to be carried away
The rest of the harness legs should be simple to route, dont forget about the grounds on the rear of the cyl heads and the two trans connectors
When I pull the engine harness I start at the passenger hush panel under the dash. Drop the ECM and unplug it along with the C207(clear connector dash side is two black halves). Next pull the retainer clip and push the pigtail back through the fender
Next, remove the pass inner fender well and pull the pigtail out and begin to push it up towards the HVAC box. Getting the fender grommet past the blower motor may take you a few minutes to figure out, but it does fit. I generally drape the harness over the engine until its ready to be carried away
The rest of the harness legs should be simple to route, dont forget about the grounds on the rear of the cyl heads and the two trans connectors
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