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 VSA modulator-control unit or the vehicle	Troubleshoot the DLC circuit.
VSA activation indicator does not come on at start-up (bulb check)	1. 2.	Do the gauge control module troubleshooting. Substitute a known-good VSA modulator-control unit, then recheck. If it is OK, replace the original VSA modulator-control unit.
VSA activation indicator does not go off	1. 2. 3.	Symptom troubleshooting. Do the gauge control module troubleshooting. Substitute a known-good VSA modulator-control unit, then recheck. If it is OK, replace the original VSA modulator-control unit.
ABS indicator, brake system indicator, and VSA indicator do not come on at same time	1. 2.	Do the gauge control module troubleshooting. Substitute a known-good VSA modulator-control unit, then recheck. If it is OK, replace the original VSA modulator-control unit.
ABS indicator, brake system indicator, and VSA indicator do not go off at same time	1. 2. 3.	Symptom troubleshooting. Do the gauge control module troubleshooting. Substitute a known-good VSA modulator-control unit, then recheck. If it is OK, replace the original VSA modulator-control unit.