Note on Intermittents

The diagnostic procedures in this section may or may not be helpful in determining the cause of intermittent problems in Antilock brake system electrical components. In most cases, the fault must be present to locate the problem effectively using the Pin-Out Checks and trouble trees.

A light sequence description from the vehicle owner may be helpful in locating a "most likely" component or circuit in the case of an intermitten failure. Use the lamp Sequence Chart, if a good description of the lamp behavior can be obtained.

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

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

^ Improperly formed or damaged terminals. All connector terminals in a problem circuit should be carefully reformed to increase contact tension.

^ 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 with the EBCM connected in an attempt to duplicate the condition and use the Lamp Sequence Chart to isolate potential causes.

Circuits which could possibly cause intermittent operation of the "ANTI-LOCK" lamp include:

^ Wheel speed sensor circuits low or intermittent output.

^ Ignition enable circuit - interruption of 12 V input.

^ EBCM switch loop circuit (low fluid/low pressure sensors) - intermittent open.

^ Main relay circuit - interruption in coil or switched battery power.