99 Grand Am

TLLM wrote"

First things first. Check out the brake fluid reservoir level and make sure it is correct. If it is low, then "sloshing" can sometimes activate the ABS system. A sudden stop can do that.

Second, check the wiring to each wheel's ABS sensor. A bumpy road can cause the wiring connectors to be intermittent, or there might be an actual break in the wire conductors.

---Bob Gross---

Actually, second should be to read the codes. Maybe even first. Without knowledge of the trouble code, you're shooting in the dark.