Topic: 14 amp Accessory fuse blowing.

[66RavenGTCoupe]

Hi all,

My 14 amp accessory fuse blows as soon as I turn the car on or to the accessory position. Can't work it out. Funny thing is that everything seems to work fine except for my temp gauge but I think that that's a different problem. My car is a GT but the rally pac was missing so I have an aftermarket one that will need to go on this circuit again as I had removed it for the engine bay restoration that I have just completed (had to pull out steering column). Any clues as to where I should look. It's driving me crazy!

Dan.

[midlife]

There are two (even three, depending upon year) 14 amp fuses.  Is this the one for:
Heater
Radio/Backup lights/accessories
Courtesy lights?

I'm guessing the radio/backup lights/accessories.  If so, here's how to trouble-shoot.  Coming off of the fusebox is a yellow or black three-prong female connector.  Remove every male bullet and start the car up.  Plug each male bullet in one at a time to see which one causes the fuse to blow.  Then track that set of wires  to see where the wire is pinched/burned/broken.  My guess is the backup light harness, as that often gets pinched by the tranny and engine.  If it is that line, disconnect the line to the backup lamps near the tail-light harness to main harness disconnect to isolate whether the short is near the firewall area or in the rear trunk area.

[66RavenGTCoupe]

Hey Midlife,
I was hoping you would reply as you've helped me in the past. I'll do that tomorrow and hopefully post up where it was.
Thanks for your help.
Dan.

[66RavenGTCoupe]

OK!
For some unforeseen reason the radio earth was plugged in there and caused it to short. Thanks for your help with that.

I have a question though. Firstly, to clarify its a 66 GT and the fuse is the top one in the fuse box marked 14A ACCY. The other male bullet connector coming out of the yellow triple female plug was black with a red stripe and it went to what I think was a voltage regulator which was held to what seemed to be the cowl just above the wiper motor with two of the same type of clips that are found on the top of the radiator support that hold the headlight loom. This silver rectangular voltage regulator (or whatever) had two flat "legs" that allowed it to be held in place by the clips. Its two posts were threaded and had a nut with a serrated washer on them. The wire leading out of it was a thicker gauge and was light blue with a black stripe. I could not see where it went and it was obviously affected by the blown fuse all that time so I'd love to know what it is connected to. Looked at 4 different wiring  diagrams and the only blue/black wire is for the courtesy lights. This is a dark blue/black wire but not the one that I am talking about. I'm thinking that whatever it is connected to may not work as it had effectively been disconnected by the blown fuse so I may need to change it.

Thanks in advance,

Daniel.

[midlife]

OK!
For some unforeseen reason the radio earth was plugged in there and caused it to short. Thanks for your help with that.

I have a question though. Firstly, to clarify its a 66 GT and the fuse is the top one in the fuse box marked 14A ACCY. The other male bullet connector coming out of the yellow triple female plug was black with a red stripe and it went to what I think was a voltage regulator which was held to what seemed to be the cowl just above the wiper motor with two of the same type of clips that are found on the top of the radiator support that hold the headlight loom. This silver rectangular voltage regulator (or whatever) had two flat "legs" that allowed it to be held in place by the clips. Its two posts were threaded and had a nut with a serrated washer on them. The wire leading out of it was a thicker gauge and was light blue with a black stripe. I could not see where it went and it was obviously affected by the blown fuse all that time so I'd love to know what it is connected to. Looked at 4 different wiring  diagrams and the only blue/black wire is for the courtesy lights. This is a dark blue/black wire but not the one that I am talking about. I'm thinking that whatever it is connected to may not work as it had effectively been disconnected by the blown fuse so I may need to change it.

Thanks in advance,

Daniel.

Wow...what a wiring screw-up with the circuit breaker.  First, the black/red wire coming out of the ACC plug is for your backup lamps.  The metal box that you describe is the circuit breaker for the fog lamps.  There should be a blue/black wire coming out of the main underdash harness with a ring connector that goes to one side of the CB, and your foglamp harness has a second blue/black wire with a ring connector that goes on the other side.

[66RavenGTCoupe]

Thanks Midlife.
Is there a diagram that can help me with this?

Dan.

[midlife]

Osborne Electrical Assembly Manual, and the Wiring Diagram Manual come to mind.

[66RavenGTCoupe]

Thanks. I was hoping you may have had one of your diagrams online that I could view?

[Brian Conway]

Hello Dan:  I recently did some work in this area, 10 amp circuit breaker, and  may be able to help.  First on my car the blu/blk wires are more like gray/blk.  The 10 amp circuit breaker is attached to the pedal support.  Test the two wire circle connections one is always hot, is from the battery. and should connect to the CB shorter brass post marked Bat.  The other wire goes to the fog light switch.  The CB was the problem in my case and was replaced.  Brian 

[66RavenGTCoupe]

Thanks Brian,
I'll test the battery side for power and trace the actual fog light switch to see where it goes and go from there. Fog lights are actually working perfectly fine with the rear park lights coming on too.