Just joined the forum and have a problem. My 02 Avalanche is driving fine, had it since new so that is no surprise; the surprise was that out of the blue the abs and brake lights lit up on the dash. I checked the underhood fuses and the pads on the rr wheel... no issue. The fluid is fine, there are no leaks and the truck drove and stopped well as I drove it carefully home. Where to look? I have had the parking brake replaced about 5 years ago, +- 40,000 mi ago, and have babied this truck.
What would trip off both dash lights?
I need to get this repaired and hope to save some time by asking, advise please.

 

Welcome to the forum. Brake warning indicator means either a closed park brake switch or brake fluid level switch. A short in the respective circuits has the same effect. I'm not sure about the other one but a closed brake fluid level switch circuit will definitely disable ABS. Try disconnecting the electrical connector from the brake master cylinder.

 

My truck has been doing this on and off for a couple of years. I have replaced the pads, rotors and calipers. I have changed the wheel speed sensors. It goes away and comes back. The only thing I have not changed is the ABS module, too expensive. When both lights come on, the ABS is disabled, other than that the truck brakes OK. Just learned to live with it. Also check the low brake fluid sensor.