Help with Wiring

[NJ_Bob 10]

I've got some strange wiring issues with my car. First of all, I have either a poor ground or low voltage condition as everything is dim. Second, I have a short where the A/C compressor get's power (clicks on) whenever I pull out the headlight switch!

 

While I can do some basic wiring & have changed the turn signal switch, I've had the wiring looked at over the years to fix some butchered wiring under the dash. There are bullet connectors & other signs of work under there but I can't seem to find anyplace that the A/C could be shorting out.

 

Also, I don't understand where my low voltage condition is coming from. I'm pretty sure the the voltage regulator is working well as the headlights etc stay steady when I rev it up. Any ideas? I'm thinking about starting to collect all of the repro harneses & replace everything myself next winter. I do have the Shelby with sequential lights. They work but are slow & dim as well.

[LindenBruce 27]

I would recommend getting a wiring diagram to help you trace wires. Also, I think your firewall connection may be dirty or corroded. It is located under the brake master cylinder. You can confirm this by checking voltage coming out of your alternator and at the battery then compare this to a voltage source at a fuse on your fuse block. Try that for starters. Bruce

[danno 128]

You need to start with a voltmeter. Check the voltage on your battery first. It should be between 14.0 and 14.6 with the motor running. If it is not, your charging system is not good.

 

If you have this voltage and your lights are still dim, you have a bad ground wire between the battery and chassis. To test for this, but your voltmeter + (red) lead on the chassis, maybe on one of the screws by the voltage regulator. Put the - (black) lead on the - termninal of the battery. Then turn on your high beam headlights. Your voltmeter should not go above 0.1 volt. If it does, you have a bad ground.

 

The ground wire goes from the back of the motor, in back of the valve cover on the passenger's side, to the firewall. It is a big black wire about 8 inches long. See if it is attached good.

[NJ_Bob 10]

Thank you! I have the wiring diagrams & a voltmeter. I'll try these tests this weekend. Any ideas on the odd short turning on my A/C compressor? I can't find any evidence of crossed wires & the A/C compressor circuit is not routing through my headlight switch according to the wiring diagrams.

Edited June 24, 2011 by NJ_Bob