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DTC 12: Diagnostic System Check: Testing

  1. Turn ignition switch to RUN position. If SECURITY indicator comes on, go to next step. If SECURITY indicator does not come on, go to step  3 .
  2. Attempt to enter Body Control Module (BCM) diagnostic mode. If SECURITY indicator flashes DTCs, system is operating properly. Go to appropriate diagnostic procedure. See BCM DTC DEFINITIONS  table under SELF-DIAGNOSTIC SYSTEM. If SECURITY indicator does not flash DTCs, go to next step.
  3. Turn ignition switch to RUN position. Operate power windows. If power windows operate, go to step  7 . If power windows do not operate, go to next step.
  4. Turn ignition switch to OFF position. Disconnect BCM connector C2. Connect test light between BCM connector C2 terminal "C" (Dark Blue wire) and battery voltage. See WIRING DIAGRAMS  . See Fig 1 . If test light comes on, go to next step. If test light does not come on, go to step  6 .
  5. Repair short to ground in Dark Blue wire between BCM and instrument panel fuse block. After repairs, attempt to enter BCM diagnostic mode. If SECURITY indicator flashes DTCs, system is operating properly. Go to appropriate diagnostic procedure. See BCM DTC DEFINITIONS  table under SELF-DIAGNOSTIC SYSTEM. If SECURITY indicator does not flash DTCs, go to next step.
  6. Replace BCM. See BODY CONTROL MODULE (BCM)  under REMOVAL & INSTALLATION.
  7. Turn ignition switch to OFF position. Disconnect BCM connector C3. Connect a fused jumper wire between BCM connector C3 terminal C12 (Gray wire) and ground. If SECURITY indicator comes on, go to next step. If SECURITY indicator does not come on, go to step  9 .
  8. Check for a poor connection at BCM connector C3 terminal C12 (Gray wire). Repair as necessary. If connection is okay, replace BCM. See BODY CONTROL MODULE (BCM)  under REMOVAL & INSTALLATION.
  9. Disconnect instrument cluster connector. Connect a test light between instrument cluster terminal A10 (Orange wire) and ground. If test light comes on, go to next step. If test light does not come on, go to step  11 .
  10. Check for an open or poor connection in Gray wire between instrument cluster and BCM. Repair as necessary. If circuit is okay, replace Instrument Panel Cluster (IPC). See appropriate ANALOG INSTRUMENT PANELS article.
  11. Repair open in Orange wire between instrument cluster and instrument panel fuse block.
Fig 1: Identifying BCM Connectors & Terminals
G99E08630Courtesy of GENERAL MOTORS CORP.
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