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Home >> Oldsmobile >> 1998 >> Bravada >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Body Control Module >> Diagnosis & Testing >> DTC B1397: 5-Volt Reference Circuit Low >> 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.
    NOTE: Ensure DTC B1397 is a current code before proceeding with test.
  2. Turn ignition switch to RUN position. Using DVOM connected to ground, backprobe Purple TBC module harness connector terminal A4 (Gray wire). If voltage reading is 4.75-5.25 volts, DTC is intermittent. See DIAGNOSTIC AIDS. If voltage is not 4.75-5.25 volts, go to next step.
  3. Turn ignition off. Disconnect Purple TBC module harness connector. Check for good connection at harness connector terminal A4 (Gray wire). If connection is okay, go to next step. If connection is faulty, go to step 7).
  4. Reconnect Purple TBC module harness connector. Using scan tool, clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check if DTC B1397 is set as current code. If code is current, go to next step. If code is not current, go to step 8).
  5. Turn ignition switch to RUN position. Using DVOM connected to ground, backprobe Purple TBC module harness connector terminal A4 (Gray wire). If circuit is shorted to ground, go to step 8). If circuit is not shorted, go to next step.
  6. Replace TBC module. Program and perform TCM module relearn procedure. See TBC MODULE PROGRAMMING/RPO CONFIGURATION  and TBC/BCM RELEARN PROCEDURE. After programming TBC module, go to step 13).
  7. Repair terminal connection. After repairs, go to step 13).
  8. Disconnect light sensor harness connector. Turn ignition off. Using DVOM, check for short to ground or open in light sensor Gray wire circuit between sensor and TBC module. If circuit is shorted or open, go to step 10). If circuit is okay, go to step 11).
  9. Replace light sensor. After replacing sensor, go to step 13).
  10. Repair Gray wire circuit. After repairs, go to step 13).
  11. Check for short to ground in White wire between TBC module and light sensor. If circuit is shorted, go to next step. If circuit is okay, go to step 9).
  12. Repair White wire circuit. After repairs, go to next step.
  13. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See TBC MODULE DIAGNOSTIC SYSTEM CHECK  .
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