Parking brake light and anti-lock brake system warning light on?

peterinvictoria

The parking brake light and anti-lock brake system warning light came on and stays on. Warning bell is ringing also. When I'm driving the anti-lock brakes engage sometimes when I brake and sometimes even when I am not braking. I brought it to my mechanic and he changed the two speed sensors on the transmission but it didn't fix the problem. If it's not the speed sensors, what else could be the problem? Thank you (2005 GMC Savana Van)

imidazol97

I assume it's a mechanical parking brake with a brake pedal on the A-pillar below the dash.
I suggest you check to be sure that is fully released and in the up position as far as it goes.

Check for a sensor device that has a button that touches the parking brake pedal or mechanism
and then moves when the parking brake is applied. That button may not be telling the system
that the parking brake is off. I suspect it grounds the circuit when the brake is applied. But check
that unit to be sure it's working properly.