ABS - Self Test Initialization Cycle Noise

91chevy10

Number: 91-241-5

Section: 5

Date: MARCH 1991

Corp.Bulletin No.: 175001R


Subject:
ABS NOISE SELF TEST


Model and Year:
1989-91 CAPRICE
1986-91 CORVETTE
1990-91 M/L VAN
1991 S/T TRUCK (4-DOOR ONLY)


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

During this test, the modulator exercises valves/solenoids/motors 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, (typically between 0-8 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.