Intermittent Faults

As with virtually any electronic system, intermittent faults in the ABS system may be difficult to accurately diagnose.

Most intermittent faults are caused by faulty electrical connections or wiring. When an intermittent fault is encountered, check suspect circuits for:

(1) Poor mating of connector
halves or terminals not fully seated in the connector body.

(2) Improperly formed or damaged terminals. All connector terminals in a suspect circuit should be carefully reformed to increase contact tension.

(3) Poor terminal to wire connection. This requires removing the terminal from the connector body to inspect.

If a visual check does not find the cause of the problem, operate the car in an attempt to duplicate the condition and record the Fault Code.

Most failures of the ABS system will disable Anti-Lock function for the entire ignition cycle even if the fault clears before key-off. There are a few failure conditions, however, which will allow ABS operation to resume during the ignition cycle in which a failure occurred if the failure conditions are no longer present. The following conditions may result in intermittent illumination of the BRAKE warning and/or ANTI-LOCK warning lamps. All other failures will cause the lamp(s) to remain on until the ignition switch is turned off. Circuits involving these inputs to the (CAB) should be investigated if a complaint of intermittent warning system operation is encountered.

(1) Low system voltage. If low system voltage is detected by the (CAB) , the (CAB) will turn on the ANTI-LOCK warning lamp until normal system voltage is achieved. once normal voltage is seen at the (CAB), normal operation resumes.

(2) Low Brake Fluid. A low brake fluid condition will cause the BRAKE warning lamp to illuminate. When the fluid sensor again
indicates an acceptable fluid level, the BRAKE warning lamp will go out. If the vehicle is in motion above 3 M.P.H., the ANTI-LOCK lamp also will be illuminated.

(3) Low Accumulator Pressure. Low Accumulator Pressure will cause both the BRAKE warning and ANTILOCK warning lamps to illuminate. Once normal operating pressure is achieved, the lamps will extinguish and the system will return to normal operation.

Additionally, any condition which results in interruption of power to the (CAB) or hydraulic assembly may cause the BRAKE warning and ANTILOCK warning lamps to illuminate intermittently.