Antilock Brake System - Operation Characteristics

NO.: 05-06-93

GROUP: Brakes

DATE: Apr. 8, 1993

SUBJECT:
Antilock Brake System (ABS 10) Characteristics And Brake Pedal Feel

MODELS:

1990-1993 (AC) Dynasty/New Yorker/New Yorker Salon
1991-1993 (AS) Caravan/Grand Caravan/Caravan CV
Voyager/Grand Voyager/Town & Country
1990-1993 (AY) Imperial/New Yorker Fifth Avenue
1991-1992 (BB) Monaco/Premier

DISCUSSION:

^ When the vehicle is first started, the yellow ABS (Antilock Brake System) light will come on and stay illuminated for 5 - 60 seconds. Also, the ABS pump motor will be running. This may or may not be heard by the operator. These are indications that the ABS is recharging itself. THIS IS NORMAL OPERATION OF THE ABS.

^ The FIRST time the vehicle is accelerated to 3 mph after start up, a momentary clicking of solenoid valves MAY be heard. This indicates the ABS is cycling through its self-check to ensure the ABS is functioning properly. The self-check will not reoccur until the vehicle is turned off, started again and accelerated to 3 mph.

^ After every 2 to 5 brake applications you MAY hear the ABS pump motor running. This will occur whether the brake applications were normal braking or antilock mode braking. The sound of the pump motor may be accompanied by a slight vibration in the brake pedal under light brake application. These characteristics indicate the ABS is recharging itself. THIS IS NORMAL OPERATION OF THE ABS.

^ When the vehicle is being stopped and the brakes are in the antilock mode, the operator of the vehicle may experience: 1) a slight brake pedal drop followed by a hard pedal feel, 2) hear clicking of the solenoid valves, and 3) increasing the force applied to the brake pedal will not increase the rate of the vehicle deceleration. THESE CHARACTERISTICS REPRESENT NORMAL OPERATION OF THE ABS.

^ During normal braking on a rough road surface, the vehicle operator may experience a slight brake pedal drop followed by a hard pedal feel and a momentary sense of a decrease in the rate of expected vehicle deceleration. THESE CHARACTERISTICS INDICATE THE VEHICLE IS BRAKING IN THE ANTILOCK MODE AND IS NORMAL FOR THE SYSTEM.

^ To achieve the shortest stopping distance when the brake system is in the antilock mode, maintain the force already applied to the brake pedal. DO NOT PUMP (REPEATED APPLICATION AND RELEASE) THE BRAKE PEDAL.

POLICY: Information Only