Symptom Chart

ANTI-LOCK CONTROL SYMPTOM CHART

Condition	Possible Sources	Action
No communication with the anti-lock brake system (ABS) module	Circuitry. ABS module.	GO to PINPOINT TEST A .
Soft/excessive brake pedal travel	Inlet (isolation) valve or hydraulic outlet (dump) valve. Leaky inlet (isolation) valve during ABS applications (soft). Brake line or hose, fitting, master cylinder, wheel cylinder or caliper.	GO to PINPOINT TEST G .
Soft/excessive brake pedal travel	Air in brake system. Brake shoe or pad linings. Parking brake. Rear axle seal.	ELIMINATE the base brake system as the cause of the problem. REFER to BRAKE SYSTEM-GENERAL INFORMATION .
ABS false activation, ABS too sensitive, ABS activates on normal stop	Front anti-lock brake sensor indicators.	INSPECT both front wheel speed sensor rings for damaged teeth. CHECK the wheel speed sensor gap.
	Chafed wire insulation or pinched wire.	INSPECT the wiring harness from the front wheel speed sensor knuckle to the frame and from the rear axle to the frame.
	Open or shorted wheel speed sensor circuit.	GO to PINPOINT TEST B .
	Rear wheel speed sensor indicator.	INSPECT the rear ABS indicator.
	Wheel speed sensor	GO to PINPOINT TEST D .
	Rear brake adjustment. Linings.	ELIMINATE the base brake system as the cause of the problem. REFER to BRAKE SYSTEM-GENERAL INFORMATION .
Wheels lock up	Hydraulic outlet (dump) valve.	GO to PINPOINT TEST G .
Wheels lock up	Leaky inlet (isolation) valve during ABS (soft). Front or rear brakes. Parking brake. Rear axle seal.	ELIMINATE the base brake system as the cause of the problem. REFER to BRAKE SYSTEM-GENERAL INFORMATION .
Vehicle pulls during braking	Sensor failure.	GO to PINPOINT TEST B .
Vehicle pulls during braking	Base brake system.	ELIMINATE the base brake system as the cause of the problem. REFER to BRAKE SYSTEM-GENERAL INFORMATION .
Anti-lock brake system (ABS) warning indicator illuminated	Circuitry. ABS module.	REFER to INSTRUMENT CLUSTER to continue diagnosis on the warning indicator.
The red BRAKE warning indicator stays on when the ignition switch is in RUN	Circuitry. Brake fluid level. Instrument cluster. Anti-lock brake system (ABS) module.	REFER to BRAKE SYSTEM-GENERAL INFORMATION for diagnosis of the red BRAKE warning indicator is always on.
The yellow anti-lock brake system (ABS) warning indicator does not self-check	Circuitry. Instrument cluster. ABS module.	REFER to INSTRUMENT CLUSTER to continue diagnosis of the warning indicator.
The red BRAKE warning indicator and yellow anti-lock brake system (ABS) warning indicator are illuminated	Dynamic rear proportioning (DRP).	GO to the ANTI-LOCK BRAKE SYSTEM (ABS) MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX .