I have a 1998 Pontiac Grand Am GT and I believe the ABS Hydraulic Modulator assembly is not functioning right. I don‘t know how to tell what‘s wrong because the ABS light isn‘t on in the car (though it is working)The problem is that the front brakes keep locking up as you drive down the road, but when you pull over, and the front brakes bring you to a stop all on there own, you can push VERY hard on the brake pedal, hold it there for a few seconds, let off and the brakes will release. Does any one have any idea what this could be? I have replaced the calipers, pads, discs, and bleed the system repeatedly hoping air was in the calipers preventing them from releasing and still no luck. the brakes work great on the stands in the garage, go down the road a mile or two and there locking up on you again.
Better traction in inclement weather.
Delco ABS VI Antilock Brake System. These have had some fairly high failure rates. But the symptom you describe is usually caused by the pistons inside the valve body not returning to their home position. There's one way to reset without a scan tool. Foot off the brake. Start the engine and let it run for at least 10 seconds. The ABS light should go ON and then off after about 3 seconds.If it does that, turn the ignition to OFF. Repeat this procedure again. THEN bleed the system.
