On-Board Diagnostics

This diagnostic procedure is used only on vehicles equipped with an anti-lock brake system (ABS). The Quick Test procedure should be used only when diagnosing ABS symptoms.

On-board diagnostics are divided into two specialized tests: the Key ON-Engine Running Test and the Continuous Test. Prior to performing either test, an inspection of the anti-lock brake warning indicator is required to determine if a fault has been detected by the anti-lock brake control module or if the system is operating normally. When the ABS is operating normally, the anti-lock brake warning indicator will illuminate during the Key ON-Engine OFF and go off after the engine has started. If the anti-lock brake warning indicator stays ON after the engine starts, this indicates a present failure. The logic circuit could keep the warning indicator on for up to 60 seconds after the engine starts. Failure codes are stored in the anti-lock brake control module until they are erased.