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Symptom Troubleshooting Chart - Anti-Lock Brake System (Abs): Notes

ANTI-LOCK BRAKE SYSTEM (ABS) - SYMPTOM TROUBLESHOOTING REFERENCE

Problem Possible Cause Action
  • No communication with the anti-lock brake system (ABS) control module
  • Circuitry or connection in the international standards organization (ISO) 9141 network
  • ABS control module
  • Loss of sensor signal during vehicle deceleration or sensor signal drops out at low speed
  • Wheel speed sensor indicator
  • Sensor output is weak
  • Air gap
  • Incorrectly adjusted rear brakes or brake shoe or pad linings grab
  • Rear brake adjustment
  • Linings
  • Base brake mechanical concern for wheels lockup
  • Rear brake shoe linings
  • Wheel cylinder
  • Rear brakes
 
  • Parking brake
 
  • Rear wheel bearing oil seal
  • Soft pedal/spongy pedal no warning indicator
  • Brake line or hose, fitting, master cylinder, wheel cylinder or caliper
  • Air in brake system
  • Base brake mechanical concern (hard pedal)
  • Vacuum boost
  • Wheel cylinder or caliper
  • Brake line or hose
  • Base brake hydraulic concern during medium/hard brake application
  • Brake line or hose, fitting, master cylinder, wheel cylinder, or caliper
  • Air in brake system
  • Base brake mechanical concern during medium/hard brake application
  • Vacuum boost
  • Wheel cylinder or caliper
  • Brake line or hose
  • Brake shoe or pad linings
  • Base brake mechanical concern for vehicle pulls
  • Rear brake
  • Caliper
  • Brake pad or shoe wear
  • Base brake hydraulic concern for vehicle pulls
  • Brake line or hose
  • One wheel locks up; no DTCs recorded
  • Caliper
  • Wheel cylinder
  • Brake linings
 
  • Hydraulic control unit (HCU)
  • The red brake warning indicator stays on when the ignition switch is in RUN
  • Circuitry
  • Instrument cluster
  • ABS control module
  • The ABS warning indicator stays on when the ignition switch is in RUN
  • Circuitry
  • Instrument cluster
  • ABS control module
  • The red brake warning indicator does not self-check
  • Circuitry
  • Instrument cluster
  • ABS control module
  • The yellow ABS warning indicator does not self-check
  • Circuitry
  • Instrument cluster
  • ABS control module
  • The yellow ABS warning indicator self-checks OK but automatically begins flashing
  • Circuitry
  • Instrument cluster
  • ABS control module
  • ABS hydraulic control unit
  • RETRIEVE the DTCs and go to the appropriate pinpoint test.
  • Soft/hard/excessive brake pedal travel
  • Brake line or hose, fitting, master cylinder, wheel cylinder, wheel cylinder or caliper
  • Air in brake system
 
  • ABS hydraulic control unit
  • The yellow ABS/red brake light always on, no DTCs
  • Circuitry
  • ABS control module