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I have been working on my '54 GMC for a while now, have electric troubles I just can't solve. I have finally got all the tail lights, license plate light and parking lights working. I am having fits with the turn signals. I finally got the left one working, but not the right one. Also have brake lights only on the left side. Any suggestions, I'm kind of at a dead end?

Chevman32,

Because the the brake is also the turn, the problem could be in the turn signal unit itself as well as the taillight assembly.

You have the left one working so it can act as your 'demo' while you troubleshoot the right side.

Assuming all the wires are intact, you need to see if the brake/turn signal is making it back to the light, which means the turn signal unit is OK and there is something wrong with the ground or lamp assembly..OR, it isn't making it that far and the problem is in the turn signal unit itself.

A voltage tester or ohmmeter can help you find out how far your signal is making it. This will narrow the search...it's either up front or it's in the back. Make sure your taillight assembly is well grounded to the bed and frame.

Stuart

I have separate wires for the lamps needed at the rear of my truck. you should have a brake wire to the rear of the truck along w/ a left and right wire and taillamp wire. if you want to run a good (scraped metal frame) ground wire also. that's 5
get and learn how to use a simple VOM, volt ohm meter. disconnect everything first & trace your wires and make sure they are good, have continuity to the brake switch, both turn signals, the ground is good and the taillamp goes to the light switch and it's good. check the operation of your turn signal on the ohms scale.
once you know that, wire up the rear,
taillamps, brakes & left/right
make sure inside your housings that none of the wires are open, pinched, grounded or shorted to any other lamp.
It's a step by step process prove it all good first. build the path, check the ends.
Draw up on a sheet of binder paper the wires as you have them, colors etc & file it away when done.

If as stu says you use your brake lamp wire(s) as turn signals, ... that probably has to be a separate circuit within the turn lamp signal controller. unless the brake bulb is a dual filiment/ tail.

If you can post some info about your truck I will make you a wiring diagnostic chart that will provide a step by step procedure for repairing your lighting problems.

1. Front lighting: How many lamps are involved with the park and turn opperation? Inside each lamp how many bulbs are there? If 1 bulb is in each lamp how many filiments are in that bulb. If 2 bulbs are in each lamp are they both single element bulbs?
2. Rear lighting: How many lamps are involved? How many bulbs are involved in each lamp? Do you have back up lamps in the same lamp as the park/brake/turn lamp? How many filiments are in each bulb?
3. Are your turn signals factory installed or aftermarket kit. The kits usually require additional lamps to be installed.

With this info and your e-mail address I can send you a diagram and instruction on how to test the system. The only tools you need should be: test lamp, small wire brush, some emory cloth, can W/D 40, and a 3 foot length of 14 guage wire with alligator clips installed on both ends. James