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DTC B1478: Retained Accessory Power Circuit High: Testing

  1. Perform RETAINED ACCESSORY POWER (RAP) DIAGNOSTIC SYSTEM CHECK  . Go to next step.
  2. Connect scan tool to DLC. Turn ignition switch to RUN position. Using scan tool, command RAP relay ON and OFF. If RAP relay operates as commanded, go to DIAGNOSTIC AIDS  . If RAP relay does not operate as commanded, go to next step.
  3. Turn ignition switch to OFF position. Remove RAP relay from left I/P accessory junction block. Turn ignition switch to RUN position. Connect a test light between ground and RAP relay control circuit connector terminal H2. Using scan tool, command RAP relay ON and OFF. If test light turns on and off as commanded, go to next step. If test light does not turn ON and OFF as commanded, go to step  5 .
  4. Connect a test light between RAP relay control circuit connector terminal H2 and RAP relay ground circuit connector terminal K3. See WIRING DIAGRAMS  . Using scan tool, command RAP relay ON and OFF. If test light turns on and off as commanded, go to step  8 . If test light does not turn on and off as commanded, go to step  10 .
  5. If test light remains illuminated with both commands, go to step  7 . If test light does not remain illuminated with both commands, go to next step.
  6. Check for open or short to ground in RAP relay control circuit (Black wire) between left I/P accessory junction block harness connector C1 terminal F11 and BCM harness connector C2 terminal B9. See Fig 1 and Figure . Repair as necessary. See WIRING DIAGRAMS  . After repair, go to step  13 . If RAP relay control circuit is okay, go to step  9 .
    Fig 1: Identifying Left/Right I/P Accessory Wiring Junction Block Harness Connector
    G00009286Courtesy of GENERAL MOTORS CORP.
  7. Check for short to power in RAP relay control circuit (Black wire) between left I/P accessory junction block harness connector C1 terminal F11 and BCM harness connector C2 terminal B9. See Fig 1 and Figure . Repair as necessary. See WIRING DIAGRAMS  . After repair, go to step  13 . If RAP relay control circuit is okay, go to step  9 .
  8. Check for poor terminal contact at RAP relay connector. Repair as necessary. After repair, go to step  13 . If terminal contact is okay, go to step  11 .
  9. Check for poor terminal contact at BCM harness connector C2. Repair as necessary. After repair, go to step  13 . If terminal contact is okay, go to step  12 .
  10. Repair open or high resistance in ground circuit (Black wire) between left I/P accessory junction block harness connector C1 terminal E11 and ground. See WIRING DIAGRAMS  . After repair, go to step  13 .
  11. Replace RAP relay. After repair, go to step  13 .
  12. Replace BCM. See BODY CONTROL MODULE (BCM)  under REMOVAL & INSTALLATION. Perform new BCM setup. See NEW BCM SETUP  under PROGRAMMING. After programming BCM, go to next step.
  13. Clear DTCs. Operate system to verify repair corrected fault. If fault still exists, go to step  2 .
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