73 Challenger Headlight switch rebuild question?

[Stockcar axeman]

I am restoring my Challenger and I want to either restore it myself or have someone restore with experience. Is it something that a electrical novice can do or best left to someone with experience? Any recommendations on on a shop that does these things? Thanks for any advice.

 

[DetMatt1]

The guy I would have do it is Devin. He is a member here but I don’t know how often he checks in.
I’ll let him know you’re inquiring.
@devinism

 

[Juan Veldez]

I used Tommy White of Parts Hound, (262)685-8943. He's in Wisconsin.

 

[EW1BH27]

If you try it yourself be careful opening it up. I broke off a piece of the housing trying to bend back one of the tabs.

 

[devinism]

PM sent

 

[Stockcar axeman]

I want to thank everyone for the quick replies and I've decided to sent it to devinism for the repair. Again thanks all for the tips!

 

[sdcbowler]

Hello everyone,

Is anyone familiar with how to test a light switch? I believe mine has gone bad. The switch is from a 1970 Challenger with standard dash. I would appreciate any advice you could offer.

Thanks

 

[devinism]

Hello everyone,

Is anyone familiar with how to test a light switch? I believe mine has gone bad. The switch is from a 1970 Challenger with standard dash. I would appreciate any advice you could offer.

Thanks

Is the switch in the car, or loose?
What are the problems?

 

[sdcbowler]

Devinism,

The switch is now out of the car. Issue is that It keeps blowing a fuse in the Cigar Lighter/Tail Lights circuit. I checked the wiring and verified everything was properly grounded. The switch has three positions (down/center/up). When the switch was in the car, I put a testlight on the small connector at the bulkhead connector. I then moved the switch between the three positions. the only time the light came on was when the switch was 'between' the middle and up positions; with all the way up turning on the headlights.......the test light also flickered and did not have a steady glow. Also while all the blinkers operate, I get no parking or side marker lights at all.

 

[pschlosser]

Initially I'm dubious a switch causes a fuse to blow.
Unless the switch, when toggled one way or the other, shorts the power to ground (or the case of the switch)

You can use an ohm meter or other tool to test continuity. Unless you can find a fault in the switch, my instinct is there is a short, elsewhere. When the switch is turned on, it then powers the short down-stream, which, in turn, blows the fuse.

You can use a wire, in place of the switch, and connect the connectors, as the switch did. If you can blow a fuse using a wire, instead of a switch, then it may be clearer the short (blowing the fuse) is elsewhere.

If not, look harder at the switch, and/or find a replacement for testing the circuit.

 

[devinism]

Devinism,

The switch is now out of the car. Issue is that It keeps blowing a fuse in the Cigar Lighter/Tail Lights circuit. I checked the wiring and verified everything was properly grounded. The switch has three positions (down/center/up). When the switch was in the car, I put a testlight on the small connector at the bulkhead connector. I then moved the switch between the three positions. the only time the light came on was when the switch was 'between' the middle and up positions; with all the way up turning on the headlights.......the test light also flickered and did not have a steady glow. Also while all the blinkers operate, I get no parking or side marker lights at all.

I agree with @pschlosser. I'm positive you have a short to ground somewhere else. Wiring, wrong bulb somewhere. Unplug the lighter and try again.
Is this a new issue with the car? If so, go back to the last thing that was 'messed with'.

You can test the switch with an ohm meter. The running / tail light circuit terminals are B2 (power in) and R (power out to all lamps except headlights). If either of those terminals have continuity to the case of the switch then it is in fact defective.
When the switch is 'between' the park and headlight positions the park / running lamps get a minute 'jump' from the headlight circuit (B1). If left this way it will definitely overheat the switch's internal circuit breaker and ruin the switch (best case scenario)

 

[sdcbowler]

I will try again,
All the harnesses are new (dash, forward lighting, and body or tail light harness). Bulbs and fuses are also new. The only thing not new is the switch, which is not from a '70 Challenger....does not have the white dot. The easiest thing to do is to test the switch to see if there is continuity between B2/case or R/case.

Will let you all know,
Thanks

 

[sdcbowler]

Devinism/Pschlosser

You both were correct. I tested the switch and there was NO continuity between any of the terminals and the case. With that eliminated from the question, I will go back and trace the circuit from beginning to end and ensure all applicable components are getting power and are also grounded as needed.

Stay tuned

 

[sdcbowler]

OK, Guys
I have an update. I checked to ensure everything was grounded. I am pretty positive I grounded everything. In looking at the schematic of the front lighting harness, I wasn't sure if the ground location at the radiator support was for the entire front lighting section or just the headlights.
1. For this reason I made sure the front valance was grounded. I didn't run any extra wires, I just made sure the valance had a good metal-to-metal contact with the lower fender.
2. I unplugged the side markers and the parking lamps from the harness. The headlights (Hi & Lo), Tail lights, license plate light, brake lights, rear blinkers and fender turn signal lights all operated perfectly.
3. I then plugged in the parking/running lights. Same result as (2.). The only difference is that the 'running or stay-on function did not work, but the blinker function did work.

**FOR THE NEXT TWO STEPS, THE PARKING LIGHTS REMAIN CONNECTED**

4. I then plugged in the passenger side marker only, moved light switch to the first position and it blew the fuse. I unplugged the passenger side marker light and replaced the fuse.
5. I then plugged in the driver side marker only, moved the light switch to the first position and it blew the fuse. I unplugged the driver side marker light and replaced the fuse.

Conclusion of this test:
Looking at the wiring diagram with my 'untrained eye', given the fact that all the other front lighting operate properly with the exception of the running function of the side markers and the front parking lamps, the common wire to these four locations is the (L6-18BK/Y*), which is position 10 in the bulkhead connector (Refer to attachment).

Next Steps:
I guess I will unplug the connector at the bulkhead, inspect at the firewall in the engine compartment and under the dash to see if anything does not look right. Then, with the connector still unpluged, I will turn the ignition switch to the on position and see how much current is present at #10 position at the bulkhead connector. Based on the results, I will determine the next step.

Any other suggestion will be greatly appreciated

 

[devinism]

It does sound like your #10 (Black with yellow tracer) is going directly to ground. Perhaps remove the parking lamp bulbs (1157, if I remember correctly), and side marker bulbs, and then check the BLK / YELLOW wire to see if it is grounded somewhere (unplugged from the firewall). With the bulbs removed it SHOULD be an open circuit.
The next step would be to do the same with all rear bulbs. With rear bulbs removed check terminal #10 to see if you get ANY ground signal (light switch on). With bulbs removed, AND the dash light dimmer unplugged, you SHOULD have an open circuit.
One other thing to look at...... The dash light dimmer switch. Same circuit. If the rheostat has come loose (common) it could ground out against the case, causing the fuse to pop.

Happy hunting

 

[sdcbowler]

OK,
I will do as you have suggested. One positive thing is that the parking lights are now working. I didn't do anything from the previous day...they just began working...the blinker and the running function.

 

[sdcbowler]

Hey Guys,

Still testing, but wanted to ask a question. How accurate is the above wiring diagram for the harness? Looking at both my new and old harnesses, it appears that at the left side marker connector (Yellow), there are two BK/Y* wires coming from the female socket and one BK wire coming from the male plug. However, when I look at the wiring diagram, it seems to indicate one BK/Y* wire coming from the female socket, and a Bk/Y* along with a Bk wire coming from the male plug. Please refer to the photos.

I am not sure which is correct and was curious to know if either of you have heard of any such thing.

Thanks much

 

[sdcbowler]

Before I go any further with troubleshooting, I wanted to show you all how my new harness is configured when compared to the wiring diagram. It is slightly different from the Wiring Diagram. Would like to hear your opinion; Please refer to the insert. Do you think the harness is built correctly and the wiring diagram is not totally accurate in terms of the wire runs, or is the harness built incorrectly?

Thanks

The blue shows the wire runs of my new harness. The red 'scribble' is the original wire runs in the wiring diagram.

 

[sdcbowler]

It does sound like your #10 (Black with yellow tracer) is going directly to ground. Perhaps remove the parking lamp bulbs (1157, if I remember correctly), and side marker bulbs, and then check the BLK / YELLOW wire to see if it is grounded somewhere (unplugged from the firewall). With the bulbs removed it SHOULD be an open circuit.
The next step would be to do the same with all rear bulbs. With rear bulbs removed check terminal #10 to see if you get ANY ground signal (light switch on). With bulbs removed, AND the dash light dimmer unplugged, you SHOULD have an open circuit.
One other thing to look at...... The dash light dimmer switch. Same circuit. If the rheostat has come loose (common) it could ground out against the case, causing the fuse to pop.

Happy hunting

In the first test:
-I removed the parking and side marker bulbs
-I disconnected the harness plug from the bulkhead connector.
-I then attached one probe to position 10 in the plug
? With the other probe, should I then touch various ground points on the body and engine?
---I am assuming that if there is continuity (signal) between Position 10 (BK/Y*) and any ground location, this is not good and indicates the wire is running to ground.

In the second test:
-I removed all the rear bulbs (parking and side marker bulbs are still removed)
-Forward harness is still unplugged
-Rear light (Body) harness is connected
-light switch on
-Dimmer switch unplugged
--I am assuming that I am now testing the other side of Position 10 from inside the vehicle underneath the dash
--I am also assuming that 'No Signal' or 'No Continuity' is the desired result.

Third test Rheostat:
-Dimmer switch still unplugged
? For this test, when trying to determine if the rheostat has come loose, do I probe between the dimmer case and any good ground point on the dash frame, or
do I probe between the dimmer case and a specific spade on the dimmer switch?
-Desired result is 'No Signal' or 'No Continuity'.