I have an 03 blazer, the brake lights work perfectly, but the third brake light (high mount stop light) only works when stepping very hard on the brake peddle... how can this be?? the brake light switch shouldn't have any effect on the each individual brake light can it?
any help is greatly appreciated.

 

I would check the grounds for the 3rd brake light. I am not sure where it is located. pull the top panel off the rear (where the rear dome light is located) the ground might be located under there.

 

Probably moisture inside the brake light lens, or a broken wire(usually between the light and the grommet that goes through the back of the roof).

 

sadly there is no ground there under the light.. i even cut the ground wire and rerouted it just in case there was a bad ground to wherever that wire goes, with no luck. i also was about to add a circuit from the brake light fuse to directly power the thing.. stupidly enough i guess there is always power through the stop light fuse, so i guess it directed through the brake light switch??? ughhhh i just want my third taillight back! any ideas at all???

 

Have you checked to see if there is power to the plug?

 

Look at the circuit board itself. A diode or something on mine burned up and caused it not to work completely. It was near the driver's side edge of the board. I replaced just the circuit board/led's and installed it all back into the housing. A new center mount stop lamp is relatively inexpensive. Back when I replaced mine years ago, they were still a pretty hefty price.



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