ABS - Noise During Self-Test Cycle

91pontiac02

Bulletin Number: 91-5-9
Reference Number: 175001
Publish Date: 2/91


Subject: INFORMATION CONCERNING ABS
NOISE - SELF-TEST NORMAL
AFTER AN IGNITION SWITCH CYCLE

Models
Affected: 1991 GRAND AM, GRAND PRIX AND BONNEVILLE MODELS


All anti-lock brake systems (ABS) will perform a self-test called Initialization during acceleration after each ignition switch cycle.

During this test, the modulator exercises the valves, solenoids and motor as the system monitors all inputs and outputs. This test is initiated at a relatively low speed so the ABS can be deactivated in the event there is an abnormal condition detected. Depending on the application, initialization occurs at different speeds, (usually 3 to 8 MPH) and will vary in intensity.

As it is possible to hear and feel the initialization cycle, some customers may comment about it. Initialization is a normal condition, therefore, repair should not be attempted.