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2002 chevy trailblazer_ls
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Discussion Starter · #1 · (Edited)
'02 TB. Am troubleshooting 3rd brake light not working. If I apply 12VDC at connecting socket, it does not light up. Indicates non-working light. Also, I get 0VDC on the other side of the socket --- input to the connecting socket. This is with brake on and other brake lights working normally. Indicates bad wire, fuse, or ???. Also, rear wiper intermittently starts operating. Starts and stops on its own accord. Works normally in all positions of the switch and will shut off then intermittently starts again for no apparent reason -- sometimes interval and sometimes constant. Eventually shuts off on its own. Problem related to 3rd brake light or two different problems?? thanks

An update 8/24. At least on the '02 the two wire cable to the connector for the high brake light does not run thru the rubber boot between tailgate and body. It runs toward the front of the vehicle just above the headliner directly from the hole you pull the connector thru. For DIYers, instead of undressing the inside of the vehicle to get to a "good" wire point, I snaked a 16ga wire and tapped into the passenger rear brake light wire and soldered it in. Re-taped and double checked for any crimp points in the wire run. Only had to do one wire as the ground wire at the connector was still good. Now have a good 12VDC supply and awaiting delivery of the new lamp. Tested the work around with a 10w lamp to make sure no fuses would blow or wires fry. Hopefully the LED's in the new high lamp will draw less than that. Seems strange the existing lamp would burn out and the supply + side would both stop working at the same time!

Would still like some inputs on the intermittent rear wiper problem. Those wires clearly run thru the rubber boot and rear control unit.
 

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2008 isuzu ascender
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990 Posts
A lot of the time the problem is in the wiring under the rubber boot between the tailgate and the body. Check the wiring under boot for breaks. This is a major wear point when you open and close the hatch.
 

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2002 chevy trailblazer_ls
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Discussion Starter · #3 ·
thanks for that input. Will try to determine if it is the + or - wire causing the problem.

Do you have an opinion on the wiper problem? My first guess was the switch at the dashboard. Seems to be a popular replacement item. Hard to see how a wire would cause the intermittent malfunction.
 

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2008 isuzu ascender
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990 Posts
Rear wiper could have the same problem , all the wiring goes thru that boot , may be intermittent.
 
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