Headlamp switch issue

[PlumKrazy71]

Hello,

I am new to the forums here and wanted to tap into some of the knowledge here to help fix an issue I am running in to. I have a 71 challenger (originally a 318 car now converted to a 440 sixpack with Rallye gauges) and I am currently in the process if replacing all the guages. While replacing the guages I have decided to finally deal with the side marker/parking lights which have not worked over the last 5 years I have owned the car.

In troubleshooting the problem I have run in to an odd situation. When I disconnect the switch, I am checking power to the pink wire at headlamp switch connector on the dash and I am getting 12v at times and I will check it again a few minutes later and get 6v at other times. I am not sure what would cause that. Additionally, I can get the side marker lights to come on if I apply 12v to the double black wires leaving the switch, but I can not get the lights to turn on or even partially illuminate using the intermittent 6v to 12v from the pink wire.

I have checked the switch and I know it is good and even replaced it with another switch that is also good. I am also able to turn on the headlights with no problems. I know that the power for the side marker lights comes from the non-fused headlamp power, to the fuse box and back to the headlamp switch at the pink wire. I have checked power at the fuse box and I get 12v there. So I assume the problem is in the pink wire coming from the fuse box to the switch. Is this the sign of a short? Any advice on what to do next would be greatly appreciated!

[734406pk]

Welcome to C-C.com!

  Power loss on the pink feed wire for the parking lights. Are you using a voltmeter for testing? Try testing the pink wire with a 12 volt test light. The light will "load" the pink wire slightly when disconnected from the headlight switch. My wiring diagram shows the first fuse on the BAT side of the fuse block protects the park lights as well as the glove box, map light and clock if equipped. Good luck!

[PlumKrazy71]

I tried a test lamp and could not get to light up on the pink wire. I did get it to work on the double black wire for the headlights. Using the Voltmeter, I am reading 12v on the pink wire, but test light won't work on the same wire. What would cause that?

[734406pk]

I tried a test lamp and could not get to light up on the pink wire. I did get it to work on the double black wire for the headlights. Using the Voltmeter, I am reading 12v on the pink wire, but test light won't work on the same wire. What would cause that?

Resistance impedes current flow not voltage(pressure). Ohms Law, boring stuff... Using a test light to load the pink wire and no light shows that you have a high resistance in that circuit. Try checking at the supply fuse and see if the test light illuminates when you switch on the park lights (circuit loaded).

[PlumKrazy71]

Ok, so I reconnected the switch and used the test light at the fuse with the switch in the middle position. The test light lit up.  So i look up and notice theside marker lights were on. They seem to be gworking fine now. But I assume it is intermittent. The only thing I changed was that I charged the Bayer last night.

[734406pk]

Awesome! Check the blades in the fuse block and make sure they are all tight and making a good strong connection too the fuse itself. Sometimes the blades can be bent and leave a loose connection at the fuse making for an intermittent power feed to the (pink) circuit.