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Fast Signal Lights After Module Replaced

Hooty

By Hooty
in Ask A GM Technician

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Hooty Enthusiast

Hooty

Posted
Posted

Background:

I was having a problem with my trailer brake lights on my 2003 Sierra 2500HD. No power to the right side trailer brake light only. All other lights were fine. (turn, tail and both brakes on the truck...turn, tail and left brake llight on the trailer). I did some research and there was no power going to the fuse in the left dash BEC panel for the right brake light.

I replaced the flasher control module on the BEC and it solved the problem. I bought a GM flasher module from a GM dealer based on the VIN # of the truck and now all my trailer lights work fine. Original problem solved.

 

New Problem:

 

When the trailer is connected the signal lights flash at a normal rate. However when the trailer is not connected, the truck lights blink very fast (as though there were a bulb burned out). I checked all the lamps and they are fine.

 

I am not sure if it is a real problem but I think it may drive me crazy with the fast flashing.

 

Anyone have any ideas? Or does anyone else have the same thing happening?

 

Thanks,

Hooty

bill190 Enthusiast

bill190

Posted
Posted

Same part number on new and old flasher unit?

 

All factory specification bulbs installed? (Not led's?)

 

All lights working?

Hooty Enthusiast

Hooty

Posted
  • Author
Posted
Same part number on new and old flasher unit?

 

All factory specification bulbs installed? (Not led's?)

 

All lights working?

 

Yes, Yes and Yes.

 

Follow up to the problem.

I checked out the old flasher unit and found one of the relays was sticking and that was causing the problem. So I put it back in to see if the trailer brake lights would work OK and they are fine. Also the signal lights are flashing as they should (not flashing fast).

 

So tomorrow I am going to go back to the dealer with the flasher unit I bought yesterday and see if they will give me a refund. If not I will see if they will exchange it for another one to use as a spare if necessary.

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