Chevrolet - Silverado1500 :: Two Brake Lights On The Dash Started Coming On Together Randomly

I have a 2000 Chevy Silverado pickup, V8, A/C, 105,000 miles, which drives like a top.

However, about a year ago, the TWO brake lights on the dash started coming on together, randomly. Sometimes the lights came on right after I started the first time, other times, they came on later in a trip after the truck warmed up.

The brakes worked perfectly, as far as I could tell. I took the pickup to the dealer, left it 2 days, and they checked the brakes, belts, tried everything (they said) including trying to get error codes on the computer. Trouble is, the lights had mysteriously gone out and refused to come back on.

A few days later, they came back on for me!! I could turn the truck off, wait a few moments, restart it, and the lights would go off, say, 80% of the time. Only to come back on later. So, I took it to a local Goodyear Tire store (while getting new tires) and they saw the lights, did a diagnosis on a computer, and got NO codes.

Now, I'm worried very much - you see, the brakes on this truck have never been changed! I've had them checked many times, always with the answer that they are still in great shape - last time, they had 30% left! I waited until the lights were ON, and drove all the way to the dealer; parked the truck running; and waited until a technician could come out and do the computer test. NO codes.

Now, I have noticed a possible pattern: when the weather is hot, as it has been most of last year here, the lights come on; when it's cold, as it's been lately, the do NOT come on. Just today, the weather warmed up into the 70s and, zap, the lights came on today.