I have a 2009 avalanche ltz. The 3rd brake light is not working I took it out and the led's are all good when I comnnected a 9v battery to the leads. Rest of my lights work fine. What the heck?

Chevy Avalanche 2007 2009 Factory Service Workshop repair manual

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I don't know----------sorry

Just look at the fastners head

Don't you own any tools for brake work

There shoul be a little relay under the blower that can get corroded from condensation check that out , it happened to mine

if the brake light switch is faulty none of the brake lights will work.......cheers

i just had the same problem, it started after having to get a "jump start" for a low battery. after checking the fuse(under the hood #43) I disconnected the battery for about 60 seconds to let the computers reset. works fine now. don't know the original cause of the low battery, or the fault but don't want to pay the dealer service charge for doing the same thing...hope this helps ..billy

If it had four or five prongs coming out of the bottom it is the relay. There should be a part number on it. If there is you can have any parts store cross that number. If not bring it in and they should be able to match it up.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

is the chech engin light on

Pull the bulb, the number is printed on it.

The crank shaft sensor is located on the passenger side front crank shaft. there is a bolt holding it there and follow the wire leads and un clip it and replace the sensor. Make sure the area is clean before working on replacing the sensor. Good luck and take care not to brake the tabs in the clips when taking the harness apart.