Light problem

[66patrick]

I'm going to take the rear light wiring off the lowered truck and swap the set out this afternoon. I know that wiring is good, so if everything is up to snuff after the wiring swap, I can re-do the wiring harness on the daily. I hate cannibalizing a good vehicle, but this will tell me what's up, for certain.

[66patrick]

OK, dig this - ALL of the lights are now working! All I did was switch out the flasher relay with the other truck, and I did this purely on a whim. I was getting ready to back the truck into the shop to change out the taillight harnesses. I was backing up and noticed the back-up lights were working! Hit the brakes, and they were working! Same with the blinkers. Maybe that was all that was wrong, was a faulty flasher relay. Damn, I hope so. This has been a real PITA to troubleshoot.

[66patrick]

I knew I'd spoken too soon. Sometime the fuel and temp gauges peg hard to the right, sometimes not. Sometimes the taillights, rear turn signals, brake light and reverse lights work, sometimes not.

At least I have arm signals to use, I have headlights and front park lights, and the heater works. Screw it.

[Oldguy]

I had to get a new canceling switch and harness for my 70 D100. Found one on Rock Auto for a reasonable price. PITA to install since the color codes were wrong but once I figured the problem out everything worked well. Not sure if that will help but wanted to let you know what fixed my rig. Good luck! Mike

[66patrick]

I'll check that out, thanks. It would be nice to be able to drive after dark.

[68fish]

Im working on same problem. make sure that the bulb socket is tight to the metal cup. On my front parking lights, this socket which is crimped in, was loose. Im going to try and put a tack weld on it.

Also, rear light go through turn signal switch. I had a missing brake light on pass side couldnt figure it out, tested everything, good ground baffled me. Plugged in a spare turn signal switch and it worked fine.

Turn signals, parking lights, brake lights are very picky about voltage drops and grounds. they can be a B to find. Easy to test ground issues using a volt meter. Just put red on pos battery and black on ground of light and see if you have close to normal volts. You should get a drop over .4 volts when compared to testing volt meter right off battery.

Fish

[Jims68]

I mentioned this about poor grounding due to the socket turning in the housing itself on my Restoration CD. You can find this part in folder: Jims68 Dodge Truck Restoration CD\#03 Photo history (WITH TEXT)\#29 Lights

For those of you that have the CD.... If you don't, here is a picture of it. I just used solder. I was afraid if I welded it, it "may" blow through because that metal is weak and I didn't want to use THAT much heat with the socket.

[66patrick]

Good ideas, both. I should check that same issue on my Imperial, as the taillights have a similar fastening manner at the socket. My brake lights come on when the headlights are turned "on", and at no other time.