A warning for early C4 owners...
Thread Starter
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
A warning for early C4 owners...
...1984 to about 1990.
somewhere about 1990/1, the Society of Automotive Engineers (SAE) changed the rules regarding the composition of wire insulation.
What this mean is, newer wire is better. It is better able to deal with heat and harsh chemicals found under the hood.
The problem - For those of us who own a pre 1991 Vette, we have a problem. The heat under the hood is slowly eating our wiring away. The insulation starts to get brittle and break, causing possible shorts and grounding conditions.
If you are having a problem with your early C4, and all other logical fixes ain't fixing it, get out a test light and a DDM and commense chasing the harness. It sure isn't pretty, but it might be your only fix.
I so can't wait for the aftermarket to make good fitting harnesses for the earlier cars.
somewhere about 1990/1, the Society of Automotive Engineers (SAE) changed the rules regarding the composition of wire insulation.
What this mean is, newer wire is better. It is better able to deal with heat and harsh chemicals found under the hood.
The problem - For those of us who own a pre 1991 Vette, we have a problem. The heat under the hood is slowly eating our wiring away. The insulation starts to get brittle and break, causing possible shorts and grounding conditions.
If you are having a problem with your early C4, and all other logical fixes ain't fixing it, get out a test light and a DDM and commense chasing the harness. It sure isn't pretty, but it might be your only fix.
I so can't wait for the aftermarket to make good fitting harnesses for the earlier cars.
Instructor
Joined: Jun 2004
Posts: 234
Likes: 0
From: 1987- L98, auto OH
Thanks Bogus, good info that I for one was not aware of! I guess we all take the wiring for granted in our cars and expect it to be almost indestructable. Thanks for the reminder. It's the simple things that seem to cause so much trouble.
Brad
Brad
Le Mans Master
Joined: Jun 2001
Posts: 6,694
Likes: 3
From: Less Talk, More WOT | Houston TX
Originally Posted by bogus
...1984 to about 1990.
somewhere about 1990/1, the Society of Automotive Engineers (SAE) changed the rules regarding the composition of wire insulation.
What this mean is, newer wire is better. It is better able to deal with heat and harsh chemicals found under the hood.
The problem - For those of us who own a pre 1991 Vette, we have a problem. The heat under the hood is slowly eating our wiring away. The insulation starts to get brittle and break, causing possible shorts and grounding conditions.
If you are having a problem with your early C4, and all other logical fixes ain't fixing it, get out a test light and a DDM and commense chasing the harness. It sure isn't pretty, but it might be your only fix.
I so can't wait for the aftermarket to make good fitting harnesses for the earlier cars.
somewhere about 1990/1, the Society of Automotive Engineers (SAE) changed the rules regarding the composition of wire insulation.
What this mean is, newer wire is better. It is better able to deal with heat and harsh chemicals found under the hood.
The problem - For those of us who own a pre 1991 Vette, we have a problem. The heat under the hood is slowly eating our wiring away. The insulation starts to get brittle and break, causing possible shorts and grounding conditions.
If you are having a problem with your early C4, and all other logical fixes ain't fixing it, get out a test light and a DDM and commense chasing the harness. It sure isn't pretty, but it might be your only fix.
I so can't wait for the aftermarket to make good fitting harnesses for the earlier cars.
Interesting info to say the least.....On that note, how much does a full wiring harness usually cost??
Burning Brakes
Joined: Jun 2003
Posts: 1,229
Likes: 1
This mean for any one with an error code, example, Code 33 (MAF)
make sure you test the wiring before changing any relays or sensors or connectors.
I bought my car with an engine bay fire and we couldn't find a used 88 wire harness so we slowly rebuilt the original one and tested every connection, I've never had an electrical problem since I've owned the car.
I wouldn't worry to much.
Just to let you guys know this regulation was also applied arround the 90's for computer Networking cables
they added some type of material to the plastic to slow down the burning process, I can't remember was it was called ( I learned it in college)
make sure you test the wiring before changing any relays or sensors or connectors.
I bought my car with an engine bay fire and we couldn't find a used 88 wire harness so we slowly rebuilt the original one and tested every connection, I've never had an electrical problem since I've owned the car.
I wouldn't worry to much.
Just to let you guys know this regulation was also applied arround the 90's for computer Networking cables
they added some type of material to the plastic to slow down the burning process, I can't remember was it was called ( I learned it in college)
Team Owner
Joined: Sep 2003
Posts: 20,179
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
This is why the insulation shrinks and leaves as much as one inch of bare wire exposed at the crimp ends. A classic of this is the fuel pump relay between the wiper motor and brake booster. Just pull the connector out and inspect the wires. 
I found the MAF power relay connector wires were exposed. So an evening was spent inspecting every last connector in the engine compartment, and repairing same.....
-JRC-
I found the MAF power relay connector wires were exposed. So an evening was spent inspecting every last connector in the engine compartment, and repairing same.....
-JRC-
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by comp
how to test?????
Thread Starter
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
the last I checked, harnesses stop at 1982. Which sucks.
How to determine the problem? Just like you would test a spark plug wire. Bend it. If the insulation breaks, you are in for fun and games.
It's a real bitch...
Wake - there are no specific problems at this time, it's just one of those things I have been meaning to share with the group.
How to determine the problem? Just like you would test a spark plug wire. Bend it. If the insulation breaks, you are in for fun and games.
It's a real bitch...
Wake - there are no specific problems at this time, it's just one of those things I have been meaning to share with the group.
Racer
Joined: Jul 2000
Posts: 363
Likes: 11
From: St. Catharines Ontario CANADA
Originally Posted by JrRifleCoach
This is why the insulation shrinks and leaves as much as one inch of bare wire exposed at the crimp ends. A classic of this is the fuel pump relay between the wiper motor and brake booster. Just pull the connector out and inspect the wires.
I found the MAF power relay connector wires were exposed. So an evening was spent inspecting every last connector in the engine compartment, and repairing same.....
-JRC-
I found the MAF power relay connector wires were exposed. So an evening was spent inspecting every last connector in the engine compartment, and repairing same.....
-JRC-
Pro
Joined: Jul 2002
Posts: 589
Likes: 1
From: Tucker GA
I don't know if this will help but I noticed on my 89 this year that the plastic wiring conduit in some areas, like close to the exhaust manifolds, was literally breaking apart due to brittleness. I am in the process of replacing all the wiring conduit in the engine bay over the next few months.
Bob
Bob
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Joined: Apr 2004
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From: All great change begins at the dinner table Ronald Reagan
Bogus, do you know if any of the '91 and earlier looms interchange with '92 or greater? I'm pretty sure the engine loom(s) won't, but what about any others under the hood & exposed?
Thread Starter
Team Owner
Joined: Aug 2000
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From: San Pedro CA
Originally Posted by redvtt
Bogus, do you know if any of the '91 and earlier looms interchange with '92 or greater? I'm pretty sure the engine loom(s) won't, but what about any others under the hood & exposed?
Thread Starter
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
Originally Posted by DAVE396LT1
This doesn's affect my '94, but someone might want to print this thread and pass it along to Painless Wiring. If there's enough of a market, it might prompt them do to a harness.
http://www.painlessperformance.com/catlarge/fichart.jpg
They don't publish prices on the page...
Team Owner
Joined: Apr 2004
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From: All great change begins at the dinner table Ronald Reagan
I was reading a Hot Rod mag article last night about dropping an LS1/6 into a '67 Chevelle. It was being done in a GM sponsored lab/plant in Arizona. They were using all off the shelf GM parts for the conversion. They did list factory part numbers for the separate engine loom for this engine install. So I'm asuming GM might have L98 engine looms as well.
I've noticed that any loom that is routed near the exhaust gets brittle. I'm hoping that the 92-96 (rest of the car) front end loom(s) are the same as pre-'92.
My concern is I do smell burning insulation (from wires) once in awhile. I don't want to wait until the car's up in smoke!
I've noticed that any loom that is routed near the exhaust gets brittle. I'm hoping that the 92-96 (rest of the car) front end loom(s) are the same as pre-'92.
My concern is I do smell burning insulation (from wires) once in awhile. I don't want to wait until the car's up in smoke!
Intermediate
Joined: Jun 2004
Posts: 35
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From: Soulsbyville CA
Crap<<<this might be the solution to all me problems. I still cant tell how fast im going. Boy am i glad you guys cought this. i have an 84 with a lot of electrical probs. Thank you ..Thank you..Thank you!!!