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DTC B1478: Retained Accessory Power (Rap) Circuit High: Testing

WARNING: This page is about a different car, the 2001 GMC Safari and 2001 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
  1. If retained accessory power diagnostic system check has been performed, go to next step. If diagnostic system check has not been performed, go to RETAINED ACCESSORY POWER DIAGNOSTIC SYSTEM CHECK  .
  2. Connect scan tool to Data Link Connector (DLC), located to left of steering column. Turn ignition switch to RUN position. Using scan tool, command RAP relay on and off. If relay does not turn on and off (click), go to next step. If relay turns on and off (clicks), go to DIAGNOSTIC AIDS  .
  3. Turn ignition switch to OFF position. Remove RAP relay from body relay block. RAP relay is located under left side of dash on data link connector bracket facing cowl, also referred to as Relay Block No. 2. See Figure . Also, see IDENTIFYING RETAINED ACCESSORY POWER RELAY TERMINAL CIRCUITS  table. Turn ignition switch to RUN position. Using a test light connected to ground, probe relay cavity terminal No. 2. If test light illuminates, go to next step. If test light does not illuminate, go to step  8 .
  4. Connect a test light between relay cavity terminals No. 1 and No. 2. Using scan tool, command RAP relay off and on. If test light does not turn on and off, go to next step. If test light turns on and off, go to step  6 .
  5. Check for short to ground or short to voltage on Black wire between relay block 2 connector terminal No. 1 and BCM connector C1 (Brown) terminal A7. If problem is found, repair as necessary. After repair, go to step  11 . If no problem was found, go to step  7 .
  6. Check RAP relay and cavity terminals for damage and poor connections. If no problem is found, go to step  9 . If connections are poor, repair as necessary. After repair, go to step  11 .
  7. Check BCM and harness connector terminals for damage and poor connections. If no problem is found, go to step  10 . If connections are poor, repair as necessary. After repair, go to step  11 .
  8. Repair power feed circuit to RAP relay. See POWER DISTRIBUTION article in WIRING DIAGRAMS. After repair, go to step  11 .
  9. Replace RAP relay. After repair, go to step  11 .
  10. Replace BCM. See BODY CONTROL MODULE  under REMOVAL & INSTALLATION. Program BCM. See BODY CONTROL MODULE  under PROGRAMMING. After repair, go to next step.
  11. Reconnect all disconnected components and connectors. Clear DTCs. Operate vehicle within code enable criteria. See CODE ENABLE CRITERIA  . If DTC does not reset, system is okay. If DTC resets, go to step  2 .
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