Sierra Brake Light Problem

I have a 2000 Sierra and my driver's side brake light won't work but the light bulb is not bad. The Passenger side light, however works. What should I check on the truck to solve this problem. Would it be between where the bulb snaps in and where the plug for the lights plug into the truck under the bed or should I check something else? Any help would be highly appreciated.

Check voltage at the connector that plugs into the back of the taillight assembly.

If you have voltage with the brakes applied then it is a bad taillight circuit board. (very common).

It's easy to fix and fairly inexpensive.

Hope this helps.

I had the same problem recently with my 99 GMC Sierra 1500. The right blinker started blinking rapidly one day. I changed out the bulb (mine actually had burned out), but 5 minutes later, the rapid blinking started again and again no brake light or turn signal.

I took the tail light socket assembly into the parts dept of the GM dealership. After the parts guys looked at it, he told me this:

Where the bulb plugs into, there is this paste-like substance that the factory puts into the sockets that is used to prevent the effects of moisture on the metal connectors of both the socket and the bulb. I forget what he called this stuff, but besides its purpose to prevent moisture in the socket, it is also electro-conductive so that the bulb gets juice from the socket. Well, this is ok until the substance dries out.

So, in my case, this stuff was dried to the point of being clay-like and the bulbs were not making a good connection in the socket. You need to scrape out that stuff from the metal connectors in the sockets. Be sure to disconnect the wires from the tail light socket assembly first, as you will probably use something metal to scrape out the dried goop and you don't want to short anything. I used a thin nail, but what would probably work better is a dental scraping type tool. You can get them at a hardware store or Home Depot.

I will also add that I live in Arizona, where it is very dry, not much rain. So, that moisture paste stuff I don't really need. If you live in an area that rains or snows alot, or you live on the coast, my solution may work temporarily until moisture has it's way with the sockets! Maybe a new tail light socket assembly might be the best bet...

Good luck!

SunDog67
1999 GMC Sierra 1500 Ext. Cab 305 (5.0 Litre)

since were on the subject, my third brake lite doesnt work, never did. ('97 bought used) I dont really care about the brake lite, but haveing the cargo lites would be nice. I'm guessing the previous owner disconnected the ground??? Any ideas???

That could be. I wonder if that cargo light socket has the same paste I spoke of earlier? And, just to ask the obvious, I assume you've checked the bulb itself. Also, my truck has a cargo light switch on the dash... possibly the switch is bad?

Hope this helps...

SunDog67
1999 GMC Sierra 1500 Ext. Cab 305 (5.0 Litre)

I have replace the brake light switch on m 94 gmc c/k1500 and I still have no brake light
help