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Another brake light problem question

fingerz2

By fingerz2
in Ask A GM Technician

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fingerz2 New Member

fingerz2

Posted
Posted

Hi I'm new to the forum hopefully someone can help me here.

 

So I have a 99 suburban k1500 4x4 2 years back my break light and turns signals started to act up replaced multi function switch and everything was good. Now I'm here today and my brake lights are not functioning. Let me start by saying my 3rd brake light has never worked in the 6 years I have owned the truck. All my signals are working including hazards. All my running lights are working. Just my brake lights will not function.

 

I can see the wires to the multi function switch but I can't find anywhere on the internet on which wires to test while depressing the brake as I know they go through there. I can't really get at the brake switch wires to test them with ease anyway so I was hoping there is another point where I can test them. I do not have a brake fuse or relay under the hood there are spots but no connectors. I'm hoping someone can tell me what wires in the multi function harness to test or provide me with another solution.

 

 

I should also mention that I parked the vehicle for most of the winter due to a bad fuel pump but as far as I remember the brake lights were working when I parked it. But not the 3rd light as mentioned previously it has never worked.

 

oldscsc Enthusiast

oldscsc

Posted
Posted

Without looking at the diagram...

 

Generally, the brake lights share 1) a signal wire (controlled by the brake light switch), 2) fuse 3) a ground.

 

First, make sure the fuse is good. Then check for voltage being sent rearward after the brake light switch. If those are both good, check the wiring for integrity of the insulation to make sure it's not shorting out, and clean and tighten the ground for the lights.

waumo1 Enthusiast

waumo1

Posted
Posted

Not saying this is your problem, but I replaced the brake light switch on my 1998 with an aftermarket switch because it was the weekend and no dealer was open. Although the switch tested OK on the bench, it did not work when installed. The second one did not work properly either. On Monday I got one from the Chevy dealer and everything was good after the install.

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