Normal Noises and Pedal Feel

COMMON DRIVER PERCEPTIONS
Below are the normal conditions that may be felt and heard by the driver of a vehicle equipped with the Teves Mark IV-G ABS or ABS with traction control. The driver will only be aware of these conditions when the system is activated during a hard braking condition, therefore, perceiving them as an abnormal operating conditions of the brake system or vehicle. Therefore, these conditions can be perceived by the driver as a concern that the ABS is not functioning correctly or that there is some other incorrect condition with the vehicle. None of these conditions will result in turning on the ABS warning lamp or the setting of an ABS trouble code.

Brake Pedal Feedback During An ABS Stop:
Brake pedal feedback is defined as a clicking and/or vibration of the brake pedal. This is a normal condition that the driver will feel through the brake pedal when the ABS is operating. This is caused by brake fluid pressure modulation in the wheel brake circuits resulting in the brake pedal feedback.

Clicking/Buzzing At Approximately 7 mph (10 kph):
This is a normal self test condition that the ABS performs to ensure proper function. The clicking/buzzing is caused by the "Pump Check" which turns on the pump/motor for a short duration (100 milli seconds) to verify operation

Groaning Sound At Approximately 7 mph (10 kph) While Driving Away From An ABS Stop:
This is a normal condition of the ABS which can occur following an ABS stop. This condition will result if the CAB has not completed a 500 milli second pump run (during an ABS stop, after the last pressure dump, and before reaching 2.5 mph (4 kph) the remainder of the 500 milli seconds must be completed at the next drive off when the vehicle reaches 7 mph (10 kph).

Groaning During Hard Braking Resulting In ABS Operation:
This condition is the pump/motor/valve noise heard by the driver during an ABS stop. This is a normal condition that the driver will hear when the ABS is operating.

When Key Is Turned To The On/Run Position, Brake Pedal Drops And A "Pop" Sound Is Heard:
This is a normal operating condition of the ABS. This noise and brake pedal movement is due to the initialization (valve pulse) occurring in the HCU.

Brake Pedal Ratchets Downward At The End Of An ABS Stop:
This is a condition that is normal for the driver to feel through the brake pedal at the end of an ABS stop. This occurs because the inlet valves in the HCU are pulsed open to bring the circuit pressures back up to the system pressures, creating the ratcheting pedal effect.

Unwarranted ABS Operation (False Cycling):
This condition is caused by the CAB interpreting marginal signals from the wheel speed sensors. This condition can be caused by the following: Wheel speed sensor to tone wheel air gap to large, damaged tone wheel, low wheel speed sensor output and sticking disc brake calipers.

Groaning Sound Between 0 - 30 mph (Vehicle Equipped With Traction Control):
This condition is caused by a front wheel(s) slipping on the road surface when accelerating the vehicle. This is a normal sound the driver will hear when the traction control system on a vehicle is operating. The green "TRACTION" lamp will be turned on and remain on until the traction control cycle is over.