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DTC 12: Diagnostic System Check: Testing

  1. Turn ignition switch to RUN position. If SECURITY indicator light illuminates, go to next step. If SECURITY indicator light does not illuminate, go to step  3 .
  2. Attempt to enter Body Control Module (BCM) diagnostic mode. If SECURITY indicator light flashes DTCs, system is operating properly. Go to appropriate diagnostic procedure. See BCM DTC DEFINITIONS  table under SELF-DIAGNOSTIC SYSTEM. If SECURITY indicator light does not flash DTCs, go to next step.
  3. Disconnect Red 2-pin SECURITY indicator light connector. Connect DVOM between ground and Red 2-pin SECURITY indicator light connector terminal "B" (Dark Green wire). If battery voltage exists with ignition on, go to step  5 . If battery voltage does not exist with ignition on, go to next step.
  4. Turn ignition switch to OFF position. Check for open or poor connection in Dark Green wire between Blue 32-pin BCM connector C1 terminal C16 and Red 2-pin SECURITY indicator light connector terminal "B". See Fig 1 . See WIRING DIAGRAMS  . Repair as necessary and retest operation. If Dark Green wire is okay, go to step  8 .
  5. Connect DVOM between ground and Red 2-pin SECURITY indicator light connector terminal "A" (Black wire). If continuity exists, go to next step. If continuity does not exist, go to step  7 .
  6. Check for open or poor connection in Black wire between Black 6-pin BCM connector C2 terminal "A" and ground. See WIRING DIAGRAMS  . Repair as necessary and retest operation. If Black wire is okay, go to step  8 .
  7. Check for open or poor connection in Black wire between Red 2-pin SECURITY indicator light connector terminal "A" and ground connection located under right side of instrument panel mounted to Heating Ventilation Air Conditioning (HVAC) plenum bracket. See appropriate wiring diagram in ANTI-THEFT SYSTEMS article. Repair as necessary and retest operation. If Black wire is okay, go to next step.
  8. Replace Body Control Module (BCM). See BODY CONTROL MODULE (BCM)  under REMOVAL & INSTALLATION. Retest operation.
Fig 1: Identifying Body Control Module (BCM) Connector C1 Terminals
G00012154Courtesy of GENERAL MOTORS CORP.
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