'72 turn signal flash on bumps

[BruthaMan]

Imagine you are sitting in a '72 truck, looking at your gauge bezel. Specifically the left turn signal indicator light.

One of the "features" I've had with my '72 since I bought it is, that every once in a blue moon when I hit a bump while driving, the left turn signal light will flash on momentarily.

All lights work normally, truck has been inspected and I drive it. Nothing really wrong, except the left side turn signal on the bezel will flash when I hit a bump. Only happens on the left signal light.

Plan to do some work on the truck this spring, so thought I'd see if anyone had suggestions on what to check, so I can add it to the work plan.

[TBONE1964]

Sounds like you are getting a momentary jolt of 12 volts to that circuit. Looking at the cluster connector, you have the high beam and the RH signal indicator feed next to the left turn. None of those would have 12 volts while driving unless you had the lights on with the brights.

I would check the connector coming out of the column and see if there is anything wires that looks like they are close to rubbing. It is getting a back feed from somewhere that is woke up by a bump.

If you have the cluster pulled out, take a good look at the printed circuit for any burn spots or damage that would cause a back feed.

The wire for the left turn signal and indicator is light blue 20 gauge wire.

[BruthaMan]

Thanks much, I appreciate the advise.

I don't have it pulled yet. I've been amassing parts for the past six months or so and when it starts warming up in the next month or so, plan to take a week off to do some upgrades.

I will be pulling the gauge cluster to replace the bezel and lens, so thought I'd see what I should be looking for while it's pulled.

Thanks again for the advise.

[TBONE1964]

Originally Posted by BruthaMan

Thanks much, I appreciate the advise.

I don't have it pulled yet. I've been amassing parts for the past six months or so and when it starts warming up in the next month or so, plan to take a week off to do some upgrades.

I will be pulling the gauge cluster to replace the bezel and lens, so thought I'd see what I should be looking for while it's pulled.

Thanks again for the advise.

Not a problem. I am curious to know what you find.

Tom

[67 Burb]

Before you start pulling things apart, is your turn signal lever loose? Can you flash the left signal with a light pressure on the lever? If the lever is very loose, maybe it moves slightly when you hit a bump. (Or how much bling-bling do you have hanging on the lever?)

I have not experienced this, I just thought it might be something to check.

[BruthaMan]

Hi Bob,

Thanks for the advice. Everything is pretty tight there, no bling hanging. Oddly enough, though, the left turn signal does not cancel properly. The right does.

I do have new "clips" or "rings" or whatever they are called, to cancel the signal after a turn and plan to put those in this spring. Also have a new dash bezel and will be putting in a quartz clock, so I'll have to be in there one way or another to check it out.

I wonder if it could be related to the cancel spring not working on the left side?

[imjeff]

I'm guessing when you put the new canceling piece in your problem will stop. The broken piece is probably allowing the weight of your lever to drop just enough to momentarily activate your left signal.

Jeff