2010 GMC Acadia Owner's Manual - Page 144

5-20 Instruments and Controls If the light comes on while driving, pull off the road and stop carefully. Make sure the parking brake is fully released. The pedal may be harder to push or, the pedal may go closer to the floor. It may take longer to stop. If the light is still on, have the vehicle towed for service. See Towing the Vehicle on page 10‑83. Antilock Brake System (ABS) Warning Light If the regular brake system warning light is not on, there are still brakes, but no antilock brakes. If the regular brake system warning light is also on, there are no antilock brakes and there is a problem with the regular brakes. See Brake System Warning Light on page 5‑19. United States Canada { WARNING The brake system might not be working properly if the brake system warning light is on. Driving with the brake system warning light on can lead to a crash. If the light is still on after the vehicle has been pulled off the road and carefully stopped, have the vehicle towed for service. Tow/Haul Mode Light The ABS warning light comes on briefly when the ignition key is turned to ON/RUN. This is normal. If the light does not come on then, have it fixed so it will be ready to warn you if there is a problem. If the light stays on, turn the ignition to LOCK/OFF. If the light comes on while driving, stop as soon as possible and turn the ignition off. Then start the engine again to reset the system. If the light still stays on, or comes on again while driving, the vehicle needs service. This light comes on when the Tow/Haul mode has been activated. For more information, see Tow/Haul Mode on page 9‑27.