The Stovebolt Site Forums The Shop Area The Electrical Bay Headlights stop turn lights from blinking

I finished wiring the 49 GMC pickup. Tried the turn signals. They work fine unless I turn on the park lamps or head lights. Then the turn lights come on but don't blink. All the lights seem to be wired to the correct side and everything.
Is this a grounding problem or is the flasher getting power from the wrong source?
Or what? ? ?

Retread,

There should be no connection between brake lights and taillights.....except a path to ground in the light fixture itself.

If your brake/tail setup uses separate lamps, the tail light might be finding ground through the brake light filament.

This is a new area for me, so I might be all wet. If you take a close look at the lamps when the problem is happening, you might see that the brake light is actually 'trying' to flash, but is only going slightly dim as the current from the tail light powers it.

You can clamp a wire to a clean spot on the frame and touch it to the base of the suspect lamp...this might cause thing to magically work.

Keep 'me' posted...I'm trying to learn 'Grounds-101'.

Stuart

Sure sounds like a ground problem. Make sure your grounds aren't trying to run through the sheetmetal and that you have a good chassis ground from the battery.

The grounds MUST run through the sheet metal to get to the light assemblies unless you run extra ground wires from the frame to the sockets themselves. Usually the ground problem is at the back of the truck, frame to bed, bed to fender and fender to light assemblies, or bed to light assemblies in some cases.

Thanks Baldy for finishing my thought. I knew what I was trying to say just needed an interpreter....lol! Make sure your sheetmetal is grounded to the chassis, so your lights aren't trying to catch ground from the battery through the sheetmetal only.

Thanks, I'll give those things a try.

Retread,

I was poking around and saw your previous "taillight" posts. It looks like there might be more to this story than was revealed here.

Stuart

Retread
Sounds like Mr. Badground has rasied it's ugly head again. Or it is just plain wired wrong.
Some questions;

Did your truck come from the factory with turn signals? (my guess is no)
Do you have sererate lights for all turn indicators? Four of them? Two of them? No extra lamps?
You can hook up turn signals with the origional lamps and only have to modify the front ones.
Let me know what you have and I will explain how.

do you have double filiments in the park lamps bulbs??
or
have you now doubled up the park and turn circuits to one filiment??
my.02

Yay! Bad ground's the culprit.
I had replaced the AD single-filament park light bulbs with dual filaments in new sockets. The right indicator worked, left didn't. I crawled under the left fender with the tire off and scraped paint for a good metal to metal contact. Still no signal. But the left park lamp lens was loose even though the bezel screw bottomed out. So when I shimmed the gasket to tighten the lens, I saw that the socket and reflector sat in a primed and painted bucket. Scraping paint where the socket touched fixed the problem. Now the truck has turn lights and four-way flashers!
For the brake and tail lights I plan to run a ground wire from the bulb mounting brackets to the frame.
Thanks the info.