Test S: Headlamps Required Indicator Always On

1. If lighting system diagnostic systems check has been performed, go to next step. If lighting system diagnostic systems check has not been performed, go to LIGHTING SYSTEM DIAGNOSTIC SYSTEMS CHECK under SELF-DIAGNOSTIC SYSTEM in BODY CONTROL MODULES - CATERA article.
2. Operate headlights verify that low beams and twilight sentinel feature operate normally. If lighting systems operate normally, go to next step. If lighting systems do not operate normally, perform lighting system diagnostic systems check. See LIGHTING SYSTEM DIAGNOSTIC SYSTEMS CHECK under SELF-DIAGNOSTIC SYSTEM in BODY CONTROL MODES - CATERA article.
3. Check for short to ground in headlamps required indicator control circuit (Brown/Yellow wire) between IPC harness connector C1 terminal No. 12 and Body Control Module (BCM) harness connector C2 terminal C7. See Figure and Fig 1 . If no problem is found, go to next step. If problem is found, repair as necessary and go to step  5 .
4. Replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION. After repairs are made, go to next step.
5. Connect all harness connectors and components that were disconnected. Verify that headlamps required indicator operates normally. If headlamps required indicator operates normally, testing is complete. If headlamps required indicator does not operate normally, go to step  2 .

Fig 1: Identifying Body Control Module Harness Connector Terminals

Courtesy of GENERAL MOTORS CORP.