C3 Interior electrical short????

[Dagored73]

Fuse panel on 73 roadster keeps blowing 20amp fuse for interior lights. This fuse also powers the alarm system and the lighter. I disconnected the lighter and the relay and flasher to the alarm to see if I could isolate the problem, but no luck. I also pulled and checked the door switches and the hood switch which were working properly. 20amp fuse still blows quickly as if its a dead short. I'm stumped. Anybody got any ideas on how to solve my delemma????

 

[pasvorto]

I had a similar problem in my 78. The short was in the wiring in the center console. I was working on the shifter. I noticed a connection that was not connected. Everytime I connected it and applied power, the fuse blew. I think it was for the alarm system. I don't know. I just left it unconnected and everything is fine.

 

[Dagored73]

C3 Interior electrical short??????

Thanks. I'll check around the console even though I haven't moved anything in that area other than the lighter wires. If it works, I'll let you know.

 

[USNA1969]

Short

I had the same problem, and it turned out that the alarm horn in the rear of the car was shorted.

 

[joe1975]

Try where your courtesy lights are wiggle the bulb right above the kick panels both sides these bulbs ground on thier brackets and the heat from the bulbs make them brittle

 

[Dagored73]

C3 Interior electrical short

This past weekend I took out the alarm switch and the horn and they seem to be working properly. I also tested the alarm relay and flasher again but nothing. I also pulled out all the courtesy lights and tested both lights and sockets and they seem to be OK. This one has me stumped. I don't have a wiring schematic of the courtesy lights/alarm. Does anybody have a copy of one ????

 

[joe1975]

Look at the courtesy light brackets they will short on any exposed area of the light socket wiggle them while they are in their mounts

 

[68Roadster]

dago,
Do a google for Don Olson of Olson Engineering, he sells poster size electrical schematics for most sharks.....sounds like you are down to shooting individual wires and looking for direct shorts to ground.....

Let me know if you can't find his address, I think I have it in the house.

 

[Mac]

Anybody got any ideas on how to solve my delemma????

Dagored73, I just emailed a copy of the wiring diagram. Hopefully, that'll help you with your troubleshooting. There's no way around it- you'll have to go through one wire at a time until you find that short.

-Mac

 

[Vetsvette2002]

This past weekend I took out the alarm switch and the horn and they seem to be working properly. I also tested the alarm relay and flasher again but nothing. I also pulled out all the courtesy lights and tested both lights and sockets and they seem to be OK. This one has me stumped. I don't have a wiring schematic of the courtesy lights/alarm. Does anybody have a copy of one ????

This guy's wiring diagrams seem pretty good...
http://www.vetteheads.com/forums/showthread.php?t=4838
http://www.vetteheads.com/forums/showthread.php?t=5458
http://forums.corvetteforum.com/showthread.php?t=1074483&forum_id=119
http://forums.corvetteforum.com/showthread.php?t=1272194&forum_id=3
http://www.corvetteactioncenter.com/forums/showthread.php?t=81199

Don

 

[Artsvette73]

The clock is also on that circuit. The coil in the clock could be shorted out. Just a stab in the dark.

 

[Florida Guy]

I love troubleshooting this kind of problem. Hope I'm not being too elementary but here goes. I would need a wiring diagram and an analog ohmmeter. Both are a necessity. Disconnect the battery neg cable. Pull the fuse. Zero the meter on RX1 scale and connect it between the load side of the fuse (not the hot side) and ground. With a dead short you will be reading zero ohms. With the doors closed (or tape the door light switches closed) disconnect all items on that circuit that you can, one at a time - lighter, clock, alarm system, whatever, while watching the meter. Keep in mind that combined bulbs in the system may read about 10 ohms. Thats only about 1.2 amps draw, which is OK. You are looking for any movement off of zero. So when you find the problem, the meter may only move slightly above zero ohms. When that happens you have isolated the circuit that has the problem. Given the age of the vehicle, I'm guessing a wire with brittle isolation that may have broken completely and is now grounded. Stick with it and you will find it.
The most difficult short I ever chased took me about 3 hours. After all of that time with no luck, I sat down in the back seat of the convertible in exaspiration. The meter went to infinity. After pulling up the seat I found that the seat spring had crushed the insulation of a wire where it went over the drive shaft tunnel. Two cents of tape cured the problem.
Good luck!