1971 Plymouth Road Runner - No tail, turn, brake, flasher lights in the rear - most logical things to check?

[AtomicDog]

I'm working on a friend's 1971 Road Runner and none of the rear tail, turn, brake or flashers are working. I also have an issue with the front running/turn signal lights staying on whenever the battery is connected. The smallest filment in the bulb stays lit on both front running/turn signal lights. In addition, the headlights work (low beam and high beam), but the headlights are dimmer than they should be. I've checked the fuse box and power is making it to all of the fuses there just fine. Does anyone know where I can find the factory wiring diagrams to download for this car and logical things to check to resolve this problem?

 

[BeepBeepRR]

https://www.mymopar.com/downloads/wiringdiagrams/1971Wiring.zip

Wiring and Electrical – MyMopar

 

[Photon440]

One of the things to check carefully is to make sure that the grounds are in circuit, not blocked by new paint or gaskets.

 

[moparker]

Rear harness unplugged from front.

 

[6872n73]

Check the light switch and connector. Check grounds.

 

[WileE]

 

[Roger63]

It's almost always the grounds as stated above

 

[devinism]

I also have an issue with the front running/turn signal lights staying on whenever the battery is connected.

Yikes! Firewall bulkhead connector issues?! Steering column wiring issues? Also remove any wiring that isn't original.

 

[AtomicDog]

Thanks for the ideas so quickly. I'll check things out further.

 

[Carcinogen]

turn signal switch in column caused me a bunch of grief. All light circuits go through it.

Instead of replacing it, previous owner rigged up switches for blinkers. Did not realize it was the turn switch until after replacing all under dash and wiring harness.

Also recommend using relays for the lights to take the load off stock wiring and switch. Much brighter and eliminates heat in switch.

 

[AtomicDog]

Just FYI, I believe I may have found the issue with the tail lights, along with the front turn signal lights staying on when the battery is connected. Traced the wiring going back to the tail lights from the driver's side kick panel. Seemed that I had current showing up in the connector at the kick panel, but no current back at the tail lights. I gently tugged on the wiring harness that ran along the floor and found that all of the wires in the harness had been cut, likely behind the back seat area. Next step is to pull the back seat and see if I can splice the 6 cut wires back together again. When I pulled the harness out, the front turn bulbs went off, so by splicing these wires back together, hoping that this solves my tail light and turn signal issues.

 

[AtomicDog]

Well, finally had some time recently and re-connected all if the cut wires tail light wires. Soldered each one back together and each one with heat shrink tubing. The wires were likely broken when someone removed the rear seat and somehow, the tail light harness got caught up on the seat frame.

The tail lights now operate, however, both right side rear turn signals are flashing dimly when I turn on the emergency flashers. Also, the front left turn signal flashes very dim, too. I get the same behavior when I use the turn signals to operate the bulbs. All bulbs are new. Any ideas as to what to look for to address this final piece of the puzzle?

 

[AtomicDog]

Just FYI, this may help others. I think I may have found the issue. The driver's side front turn signal seemed to flash very dimly (as well as the right rear turn signal bulbs), so I decided to check the wiring going to the front turn signal. When I jiggled the front driver's side turn signal wiring, everything started working as it should. I suspect that one of the wires in there is bare somewhere and must be touching the frame. I will crawl up under the car and inspect the wiring in that area further to address this issue once and for all.

 

[MoparLeo]

Check and clean all grounds and connections including inside the bulb sockets