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Home >> Oldsmobile >> 1998 >> Bravada >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Body Control Module >> Diagnosis & Testing >> DTC B2577: Headlight Control 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.
  2. Check HDLP SW fuse located in instrument panel fuse block. If fuse is okay, go to next step. If fuse is open, replace fuse and go to next step.
  3. Turn ignition off. Disconnect Light Blue TBC module harness connector. Turn headlight switch on. Check HDLP SW fuse. If fuse blows, go to next step. If fuse is okay, go to step 8).
  4. Turn headlight switch to AUTO position (if equipped). Remove HDLP PWR relay from underhood electrical center. Replace HDLP SW fuse. Turn headlights on. Check fuse. If fuse blows, go to next step. If fuse is okay, go to step 7).
  5. Disconnect 48-pin connector at steering column. Check resistance between ground and Light Blue TBC module harness connector terminal A11 (White wire). See WIRING DIAGRAMS  . If resistance is infinite, go to step 11). If resistance is not infinite, go to step 13).
  6. Disconnect connector C1 from underhood electrical center. Check resistance between ground and Light Blue TBC module harness connector terminal A11 (White wire). If resistance is infinite, go to step 11). If resistance is not infinite, go to step 13).
  7. Replace HDLP PWR relay. After replacing relay, go to step 14).
  8. Turn headlight switch to AUTO position (if equipped). Remove HDLP PWR relay from underhood electrical center. Check resistance between ground and Light Blue TBC harness connector terminal A11 (White wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 5).
  9. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B2577 is set as a current code, go to next step. If DTC B2577 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 14).
  11. Disconnect headlight switch connector. Check for short to ground in White wire between 48-pin harness connector and headlight switch connector. Repair as necessary. After repairs, go to step 14). If circuit is okay, go to next step.
  12. Replace headlight switch assembly in steering column. After replacing switch, go to step 14).
  13. Repair short to ground in White wire between TBC harness connector terminal A11 and 48-pin steering column harness connector or between underhood electrical center connector C1 and 48-pin steering column harness connector E12. After repairs, go to next step.
  14. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See TBC MODULE DIAGNOSTIC SYSTEM CHECK  .
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