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GMC Brake Lights and Turn Signal


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04-05-05, 04:46 PM   #1  
gcgrimes
GMC Brake Lights and Turn Signal

Problem was indicated by fast blink on turn signal. Noticed no brake or turn signal on driver's side, although tail lights work fine. Replaced bulbs- same problem Now fast blink has developed on passenger side with same issue. Fuses appear to be okay but will be next item replaced. Any ideas on what else to check???

 
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04-05-05, 04:48 PM   #2  
BelairBoy
u might have a wire in there goin wacky, but I would think it to be a fuse.

 
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04-05-05, 06:36 PM   #3  
You did not mention what year the truck is. In some cases, with the turn signal on, you can pull/move around the turn signal lever and the signal may work fine while doing so. This would indicate a faulty turn signal switch. You may also want to inspect the trailer harness if the truck is equipted with one.

 
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04-05-05, 08:26 PM   #4  
gcgrimes
Additional Info

Sorry!
1996 GMC Suburban 1500 4WD 5.7 L Engine
LT Package

Moving the turn signal control does not affect the blinkers neither does it affect the brake lights. Exactly what would be the problem to check on the tow connection which I do have but have not used recently.

 
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04-06-05, 02:59 AM   #5  
could be a bad turnsignal switch does the third brake light function ok?
trailer connectors are often spliced into the wiring wich can result in the wire corroding or failing due to moistire entering the area of the splice.
some trailer connections use connectors that plug into the factory harness connector wich can also corrode or cause a bad connection but is less likely to do so.

 
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04-06-05, 04:35 AM   #6  
gcgrimes
3rd Brake Light

3rd brake light works fine still. Just the driver/passenger side lights are affected. Front turn signals still work correctly. Just the rear lights are affected by the problem.

 
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04-06-05, 05:02 AM   #7  
pull the...

...lamp board from the rear lamp assembly (where the bulb goes into the socket)...turn the signal on and then wiggle the bulb in the socket or try using a jumper wire to jump from the bulb base to ground...those trucks are kinda notorious ffor connection problems back there. the fact that your indicators work and your front bulbs work says that the fuses are OK. it blinks fast because it uses a solid state flasher that senses current...when it senses a lower than normal current flow, it flashes fast...kind of a bulb out warning. (mechanical flashers would cause slow blinking or none at all) anyways...dollars to donuts that the problem is in the rear lamp assembly and it usually requires replacement of the board. do check the trailer harness connector...esp if it's the "plug in" rather than "splice on" type...

 
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04-06-05, 07:38 AM   #8  
I had a similiar problem with my earlier model Chev.

Removed the rear light housings and found that age had corroded/rusted thru the ckt. board lanes. Dealer wanted big bucks for replacements.

I cleaned up the ckt. boards as best i could,then very carefully soldered real
wires across the broken gaps. use # 22 or 20 gage wire. Still working today.
I did curse GM for that design.

 
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04-06-05, 06:58 PM   #9  
Posted By: daswede I had a similiar problem with my earlier model Chev.

Removed the rear light housings and found that age had corroded/rusted thru the ckt. board lanes. Dealer wanted big bucks for replacements.

I cleaned up the ckt. boards as best i could,then very carefully soldered real
wires across the broken gaps. use # 22 or 20 gage wire. Still working today.
I did curse GM for that design.
As stated by carguyinva as well, this is somewhat common. In the worst case, this problem would lead to the melting of the wires from the 3rd brake light, down along the left rear of the cab. It may be a good idea to inspect those wires as well.

 
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04-07-05, 06:18 PM   #10  
gcgrimes
Problem Resolved

Problem is resolved. Thanks for the input from everyone. I had to replace the boards to resolve the brake light situation. Since they are dealer parts at least they were cheap................yeah, right. But anyway the brake lights are back on.... well, on when they are supposed to be anyway. Thanks again!!!!!!!

 
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