Road Test
- Turn ignition on. Note if Red BRAKE warning light and Amber ABS warning light come on. Red BRAKE warning light is located on instrument cluster, just below tachometer. Amber ABS warning light is located on message center at center of instrument panel.
- Both warning lights should momentarily come on as a bulb check and then go off. If warning lights operate properly, go to step 5).
- If Red BRAKE warning light does not come on momentarily, perform TEST 23A: RED BRAKE WARNING LIGHT CIRCUIT under SELF-DIAGNOSTICS TESTS. If Red BRAKE warning light remains on steady with ignition on, check control valves in standard brake system. See BRAKE SYSTEM article.
- If Amber ABS warning light does not come on momentarily, perform TEST 24A: AMBER ABS WARNING LIGHT CIRCUIT under SELF-DIAGNOSTICS TESTS. If Amber ABS warning light remains on steady, retrieve and record DTCs and then clear DTC from CAB. See RETRIEVING DIAGNOSTIC TROUBLE CODES and CLEARING DIAGNOSTIC TROUBLE CODES.
- Drive vehicle at a speed of at least 10 MPH and note if Amber ABS warning light comes on steady. If Amber ABS warning light does not come on, go to next step. If Amber ABS warning light comes on steady, retrieve Diagnostic Trouble Code (DTCs). See RETRIEVING DIAGNOSTIC TROUBLE CODES .
- Continue driving vehicle. Ensure vehicle attains a speed of 25 MPH. Bring vehicle to at least one complete stop, and then again accelerate to at least 25 MPH. If Amber ABS warning light comes on steady, retrieve Diagnostic Trouble Codes (DTCs). See RETRIEVING DIAGNOSTIC TROUBLE CODES .