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 is divided into two specialized tests: "Key ON, Engine Running Test" (KOER) and "Continuous Test." Prior to performing either test, an inspection of the anti-lock brake warning indicator is required to verify that indeed a fault has been detected by the anti-lock brake control module or if the system is operating normally.

When the ABS system is operating normally, the anti-lock brake warning indicator will illuminate during 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 anti-lock brake warning indicator ON after the engine starts for up to 60 seconds. Failure codes are stored in the anti-lock brake control module until they are erased.