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Turn Signal Erratic [ Turn Signal blinks erratically ]


Full Member
May 11, 2005

For the past few weeks, while I am driving every now and then I turn my turn signal on and it starts flashing very fast, then slow then fast again, almost like a light bulb is out, which there is not. If I step on my brakes both blinkers come on dim (talking from looking at my dash board). If I then turn on my flashers the "problem" goes away.

Man I hate electrical problems (and I am a electronics engineer).

Any ideas of what this might be? Anyone?

The only thing that I have changed since this started was I moved my trailer plug into my bumper, but I did not do anything to the wiring, just drilled a new hole and moved it from the hitch to the bumper.

I was also thinking maybe I have a grounding issue, but where do I even start looking for a bad ground?  Does anyone know where all the ground points are on this truck?  2003 Z-71

Any help would be great guys/gals.
Check your bulbs. My old tahoe was doing that once and it was a signal that bulb was out. Easy fix. Hope this is your problem!
I have checked all my bulbs and it don't seem to have any burnt out, but I guess it could be a bad bulb connection.
The steady dim when you apply the brakes I think is going to be the key. Sounds like your brake light circuit is grounding through the flashers. I know you said you checked the bulbs already, but I would try replacing them if that isn't how you checked them. Just in case you have a filament partially touching. Could explain the intermittent nature. Other than that, I would do a continuity test from the ground side of each light socket to a known good ground (trailer plug will work well since you're back there). Sorry I don't know exactly where the grounds are for the tail lights. Pic is in case you decide to use the trailer plug.


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