ABS - Pulsation or Kickback

9211infiniti02

Models: All models

Section: Brake System

Classification: BR90-001

Bulletin No.: ITB90-027

Date: September 14, 1990


ABS "SELF-CHECK" PULSATION


APPLIED MODELS: 1990/91 Q45 (G50)
1990/91 M30 (F31)
1991 G20 (P10)


SERVICE INFORMATION:

The Q45, M30, and G20 models are equipped with Anti-Lock Braking System (A.B.S.) as standard equipment.

Some customers may notice that a "pulsation" or "kick back" can be felt in the brake pedal when their vehicles are initially driven in a forward or reverse direction after the engine has been stopped for a period of time. This condition is most likely experienced when driving in reverse as the driver's foot is usually on the brake pedal while in reverse gear. Sometimes a brake "clunk" noise can be heard at the same time as the pulsation. This condition is caused by the A.B.S. system performing a selfcheck or self diagnosis and is normal.

The first time the vehicle reaches 4 mph or greater in forward or reverse gear after engine starting, the "self-check" function will occur. This check automatically activates the A.B.S actuator causing the brake pedal to momentarily pulsate. The customer may not always notice this phenomena depending on: vehicle speed, the length of time that the vehicle has been at rest with the engine off, and whether the customer has applied the brake pedal when the "self-check" occurs.