64 Corvette wiring problem
Thread Starter
3rd Gear
Joined: Jun 2009
Posts: 3
Likes: 0
From: Fort Worth TX
64 Corvette wiring problem
I just replaced the tail lights and the rear wiring harness in my 64 roadster. Now the tail light fuse blows every time that I pull the headlight switch. If anyone has any ideas I would appreciate hearing them. Thanks for the help.
Le Mans Master
Joined: Feb 2008
Posts: 5,214
Likes: 447
From: NJ Hockey beer league
I just did this job on my 64 Coupe. First, if the harness is a new good quality one (like Lectric or M&H) unless you pinched a wire somewhere, I doubt the problem is in the harness itself. I would start at the rear, and unlug all the tail lights first (especially if they are new) and see if the short goes away (Do the turn signals work OK??). I had one that was assembled incorrectly and did not work. Next, work your way back towards the front making sure the harness did not get pinched somewhere or a screw (near the door sills) or wire cover clip did not pierce it. 
Pilot Dan
Pilot Dan
Thread Starter
3rd Gear
Joined: Jun 2009
Posts: 3
Likes: 0
From: Fort Worth TX
64 Corvette wiring problem
Thanks. I do have an M&H harness. I went back and disconnected each lead and ground until I worked my way forward to the body connection plug. Now all of the wiring harness leads are disconnected. The tail light fuse (second from the bottom?) is still blowing when I plug the harness to the body connector and pull on the headlight switch. What would you do next?
Le Mans Master
Joined: Feb 2008
Posts: 5,214
Likes: 447
From: NJ Hockey beer league
Without touching the headlight switch, and the key in the on position, does your gas guage register? Do the turn signals work? How about the tail lights when you step on the brake? If these items all work with the key on, I think you can rule out the harness and start looking for a short up front in one of the connectors. Also check to be sure none of the wires have come loose from the turn signal connector or the plug for the front harness. Finally, one dumb question, are you SURE you have the correct harness for your car??? Coupe & Vert, back up light or no?? Check the new harness against your old one and see if all the colored wires are in the same pin positions on the new one. It should be a simple plug in up front. If it worked before, the new harness should also work unless there is some difference like you got the wrong harness. Keep at it, something will eventually reveal a dead short. Pilot Dan
Pilot Dan
Thread Starter
3rd Gear
Joined: Jun 2009
Posts: 3
Likes: 0
From: Fort Worth TX
Thanks for the ideas. With the key on, the turn signals and the gas gauge work. The tail lights, the license plate light and the stop lights don't work. I checked the harness number with M&H and it appears to be correct. The wire colors match at the body connection plug and they match the wiring diagram and they match the old harness. The differences between the old and new harneses are: 1. The old lights and harness were set up for the turn signals to only blink in the outboard lights and the new lights and harness have both the inboard and outboard lights blinking. 2. The old harness had an extra wire with a seperate plug on the body connector end (black with a light green stripe). If I read the wiring diagrams correctly, it appears that the car may have originally have been wired for back-up lights.
I don't have much experience with electrical troubleshooting, but I appreciate your help and am now concentrating on the under dash wiring, connectors and grounds. I'll post it if I find a solution.
I don't have much experience with electrical troubleshooting, but I appreciate your help and am now concentrating on the under dash wiring, connectors and grounds. I'll post it if I find a solution.
Tech Contributor
Joined: May 2005
Posts: 15,576
Likes: 118
From: Conroe Texas
Yep, the old harness sounds like it was for a car with backup lights, which means your main dash harness may be as well. (Did 64's even have backup lights as an option? I'm not sure)
Do you have a plug like this one hanging out on your firewall? This is the backup light connector that joins the main dash harness to the wiring from the backup light switch. I don't know if mismatching the harnesses could cause things to blow a fuse.
Do you have a plug like this one hanging out on your firewall? This is the backup light connector that joins the main dash harness to the wiring from the backup light switch. I don't know if mismatching the harnesses could cause things to blow a fuse.
Le Mans Master
Joined: Feb 2008
Posts: 5,214
Likes: 447
From: NJ Hockey beer league
Yes, 64's had back up lights. Give M&H a call and they may have a wiring solution for you with the harness you have (like eliminating or moving a wire), otherwise I would see if you can exchange it for a different harness that would be compatible with the dash main harness with back up lights and put it back the way it was before. Pilot Dan
Pilot Dan
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Instructor
Joined: Mar 2006
Posts: 199
Likes: 26
From: tucson az
Trouble Shooting
Try this first, remove all the lamps from their sockets and unplug the harness. Next thing requires the use of a multi- meter use the resistance scale and with one probe attached to a good ground use the other probe and test the wires on the connector one at a time there will be a ground wire that will have zero ohms and the rest should read infinity. I'm sure you will identify the bad wire or at least know the color that you can trace out. Hope that was some help.
Retired EE
Retired EE
