The Stovebolt Site Forums The Shop Area The Electrical Bay 1953 GMC Turnsignal ???

I've installed a turnsignal switch assembly on my 1953 GMC and the left front works fine and is bright, but when I try the right side both front turn signals flash but are very dim. When the 4-way flashers are activated the right front is very dim and the left front is very bright. Any help is much appreciated.

What is the brand/make and model number of the switch?

Sounds like a ground issue with the right light

I checked and there is not a brand/ model number on the switch. I purchased it from Classic Parts and the wiring harness for a one wire alternator. It attaches to the steering column and the 4-way flasher has a red knob that pulls out. It has 7 wires. The wires from the parking lamps: 1 goes to the terminal board on the fender well, and the other goes to the switch. It follows the old post by KCMONGO that has a colored and numbered wiring diagram for 47-53

As TRUCKBIZ said. It's the ground. Probably the ground of the right front bulb socket/housing/body attachment. Run a test wire from the battery ground post to various metal spots in and around the lamp while it's set on blink. Start with touching directly on the bulb case. If that makes it all work, then find out where it is loosing ground from bulb case to body/battery.

Bulb case: The brass part of the bulb that the glass is attached to. Take off the lens to get access to it with a test wire probe.

Repair: (if testing confirms ground issue at bulb)
1. Examine attachment method of the lamp components.
2. Look for looseness, corrosion, rust. Clean/burnish or replace bulb socket and housing.
3. Compare to other side to see if anything is missing/damaged.
4. Be sure bulb bayonet pins have good contact to socket.
5. Add a ground wire.

If you are saying that both front signals flash when just the right is activated, that means the right is looking for ground and may be feeding back thru the other bulb. It's weird, but that's what it does sometimes.

Of course, there is the possibility that you have made a wiring error.

You never said anything about what the rear lamps are doing.

Does the right rear signal working properly?
Does the left front and rear work properly?
The ONLY issue is that when right is activated, both front lamps blink and......... when hazard is activated, right is dim. No issue with rear. Correct?
6V or 12V?

Sorry, I should have mentioned the rear tail lights. The rear tail lights are functioning as they should, either right or left only and with the 4-way. That is correct that when the right front is activated both front lamps blink, but very, very dim.

Bartamos, thank you for the great information and step-by-step how to. I found where I didn’t have the ground. I added a wire and all works fine. This forum is fantastic with a wealth of information

Good job in finding the problem. Happy to help. TRUCKBIZ called it.