66 c10 tail light wiring problems
 

:waah:i am having trouble with my lights not working. The running lights work but the passenger side brake light does not light up while brake is being hit. has anyone had this problem or have a wiring diagram to help? wires are a mess so it is very hard to tell if anything is not right. not sure if its had a 65 bed put on it or if its the 66 bed but has no back up lights, thanks for any help
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Re: 66 c10 tail light wiring problems
 

I just ran the intermediate one with 4th wire (light green).
Brown to lights on. Green right, Yellow left. At rear wires are black and white(neutral).
Before you get crazy check the grounds on taillights. Screws to body inside lights.

Re: 66 c10 tail light wiring problems
 

I agree. Check your grounds. I ran a ground strap from the taillight housing to the frame on both the left and right sides. Be sure and scrape away all the grease, oil and paint. Bare metal only.

Even after this, there were issues. Make sure the bulb is properly seated in the socket as that messed me up as well. Just stay after it...you'll get it!

Tom

Re: 66 c10 tail light wiring problems
 

When I've had this problem it was due to poor grounding. This circuit tester is my best friend whenever I have these types of problems: http://www.harborfreight.com/circuit-tester-30779.html

There's a connector on the driver's side (US) at the firewall. You could make sure power's getting through there (you'd need someone to press the brake or a piece of wood to hold the brake pedal down.

There's another connector near the rear (my bed doesn't have wood, so it's easier to test).

Re: 66 c10 tail light wiring problems
 

There is supposed to be a connector on the DS at the frame rail end.

I would check the bulb socket after you ensure the bed is grounded.

I grounded my truck, eng to cab, eng to frame, cab to Gram, bed to frame at front and rear( opposite sides)core support to frame

Re: 66 c10 tail light wiring problems
 

Does your RIGHT turn rear light work?..... IF it does and you have left brake light then the problem is in the turn signal switch

Re: 66 c10 tail light wiring problems
 

I'm having the same issue with my '66 except it's the left side brake! Have both tail lights and both turn signal lights but only the right brake light. Had the turn signal switch replaced in June so you're suggesting that I probably need to replace the switch again?

Thanks

Rope

Re: 66 c10 tail light wiring problems
 

I ran a ground from my battery negative to all the lights in the rear. Did the same in the front, no more lighting problems.

Re: 66 c10 tail light wiring problems
 

Using silicone paste at all the connections including the bulb socket will help as well.

Re: 66 c10 tail light wiring problems
 

IF you have BOTH turn lights (and only one brake) then problem is in switch you can open it up and bend the contacts to get it working....... there is a post here somewhere that has pics of this problem and the fix

Re: 66 c10 tail light wiring problems
 

Appreciate the help!

Re: 66 c10 tail light wiring problems
 

Also make sure your turn signal lever is in the neutral position