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Home >> Chevrolet >> 1998 >> Blazer 2D Utility, 4WD, Automatic >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Body Control Module >> Diagnosis & Testing >> DTC B1480: Inadvertent Power Circuit Malfunction >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform TBC module diagnostic system check. See procedures in TBC MODULE DIAGNOSTIC SYSTEM CHECK  . After performing system check, go to next step.
  2. Ensure DTC B1480 is a current code. Check CTSY LP fuse (located in BBEC). If fuse is okay, go to next step. If fuse is open, go to step 11).
  3. Turn ignition switch to RUN then to OFF position. Using scan tool, ensure inadvertent power relay is on. If relay is on, go to step 24). If relay is not on, go to next step.
  4. Remove inadvertent power relay from BBEC. Turn ignition switch to RUN position. Check voltage between ground and BBEC cavity for inadvertent relay circuit No. 40. See WIRING DIAGRAMS  . If battery voltage is present, go to next step. If battery voltage is not present, go to step 12).
  5. Check resistance between relay terminals No. 1 and 2. If resistance is about 95 ohms, go to next step. If resistance is not about 95 ohms, go to step 15).
  6. Disconnect Brown TBC module harness connector. Check resistance between BBEC terminal C4 (Dark Blue wire) and TBC module harness connector terminal A8 (Dark Blue wire). If resistance is 2 ohms or less, go to next step. If resistance is not 2 ohms or less, go to step 16).
  7. Connect a fused jumper wire between battery voltage and inadvertent power relay terminal No. 2. Connect another jumper between ground relay terminal No. 1, energizing relay. Check resistance between relay terminals No. 3 and 5. If resistance is about 2 ohms, go to next step. If resistance is not about 2 ohms, go to step 21).
  8. Check for poor connection from inadvertent power relay to BBEC. If connection is okay, go to next step. If connection is faulty, go to step 22).
  9. Reconnect all components and wiring. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B1480 is set as a current code, go to next step. If DTC B1480 is not set as a current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  10. Replace TBC module. Program TBC and perform relearn procedure. See procedures in TBC MODULE PROGRAMMING/RPO CONFIGURATION  and TBC/BCM RELEARN PROCEDURE  . After programming module, go to step 25).
  11. Ensure circuit No. 40 (Orange wire) between BBEC and courtesy light fuse is not shorted to ground. Repair as necessary and replace CTSY LP fuse. After repairs, clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. check DTCs. If DTC B1480 is set as a current code, go to step 23). If DTC B1480 is not set as a current code, go to step 25).
  12. Disconnect BBEC harness connector. Check voltage between ground and BBEC harness connector terminal A4 (Orange wire). If battery voltage is present, go to step 14). If battery voltage is not present, go to next step.
  13. Repair open in Orange wire between BBEC and courtesy light fuse. After repairs, go to step 25).
  14. Check for poor or loose connection at BBEC harness connector terminal A4 (Orange wire). Repair as necessary. After repairs, go to step 5). If terminal connection is okay, go to step 20).
  15. Replace inadvertent power relay. After replacing relay, go to step 25).
  16. Disconnect BBEC harness connector. Check resistance between BBEC harness connector terminal C4 (Dark Blue wire) and Brown TBC module harness connector terminal A8 (Dark Blue wire). If resistance is 2 ohms or less, go to next step. If resistance is not 2 ohms or less, go to step 19).
  17. Check resistance between BBEC connector terminal C4 (Dark Blue wire) and inadvertent power relay cavity No. 1. If resistance is 2 ohms or less, go to next step. If resistance is not 2 ohms or less, go to step 20).
  18. Check for loose or poor connection at BBEC harness connector terminal C4. Repair as necessary. After repairs, go to step 25). If connector terminal is okay, go to step 20).
  19. Repair open in Dark Blue wire between BBEC and TBC module. After repairs, go to step 25).
  20. Replace BBEC. After replacing BBEC, go to step 25).
  21. Replace inadvertent power relay. After replacing relay, go to step 25).
  22. Repair poor connection. After repairs, go to step 25).
  23. Check for short to ground or open in circuit No. 1732 (Orange wire), including a short in any of the light request input circuits. Repair as necessary. After repairs, go to step 25). If circuits are okay, got step 10).
  24. Reconnect all components and wiring. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B1480 is set as a current code, go to step 23). If DTC B1480 is not set as a current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  25. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See TBC MODULE DIAGNOSTIC SYSTEM CHECK  .
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