Antilock Brakes / Traction Control Systems: Service Precautions
Precautions in Diagnosing TroublesTo ensure that the trouble diagnosis is done accurately and smoothly, observe the following and follow ABS Check.
^ If the vehicles was operated in any of the following ways, ABS warning lamp may light momentarily but this does not indicate anything abnormal in ABS.
^ The vehicle was driven with parking brake pulled.
^ The vehicle was driven with brake dragging.
^ The vehicle was stuck in mud, sand, etc.
^ Wheel spin occurred while driving.
^ Wheel(s) was rotated while the vehicle was jacked up.
^ Be sure to read Precautions for Electrical Circuit Service before inspection and observe what is written there.
^ Be sure to use the trouble diagnosis procedure as described in ABS Check. Failure to follow it may result in incorrect diagnosis. (Some other diagnosis trouble code may be stored by mistake in the memory of ABS control module during inspection.)
^ When disconnecting ABS hydraulic unit / control module connector (1), pull down lock lever (2) of connector.
When connecting, set the connector on ABS hydraulic unit / control module assembly and pull up the lock lever (2) until it locks.
^ Inspect the vehicle for any mechanical conditions related the brake system.
^ Brake reservoir fluid level correct.
^ Inspect master for fluid for contamination.
^ Inspect brake master/ modulator for leaks.
^ Inspect brake components at all wheels.
^ Verify no brake drag exists (brake switch adjustment).
^ Verify even brake apply (no pull or lead).
^ Inspect for worn / damaged brake pads.
^ Inspect for worn / damaged wheel bearings.
^ Inspect wheel speed sensors / wiring.
^ Inspect harness connectors / wheel speed sensor rotors for damage.
^ Inspect tires for tread depth / wear.
^ Road test the vehicle to verify the complaint.
^ Current DTC memorized in ABS control module can not be cleared, but history DTC can be cleared.
^ Current DTC is memorized as history DTC to ABS control module when ABS control module diagnoses conditions of the system as normal.
Precautions in On-Vehicle Service
When connector is connected to ABS hydraulic unit / control module assembly, do not disconnect connectors of sensors with ignition switch ON. Then DTC will be set in ABS control module.