When the vehicle has one of these symptoms, check for a diagnostic trouble code (DTC) with the HDS. If there is no DTC, do the diagnostic procedure for the symptom, in the sequence listed, until you find the cause.

Symptom	Diagnostic procedure
HDS does not communicate with the ABS modulator-control unit or the vehicle	Troubleshoot the DLC circuit.
ABS indicator and brake system indicator do not come on at the same time	1. 2.	Do the gauge control module troubleshooting. Substitute a known-good ABS modulator-control unit, then retest. If it is OK, replace the original ABS modulator-control unit.
ABS indicator and brake system indicator do not go off at the same time	1. 2. 3.	Check for F-CAN DTCs, and troubleshoot and repair those first. Symptom Troubleshooting. Do the gauge control module troubleshooting.