1997 Buick Century CustomFACTORY OEM SERVICE PROCEDURE

BCM Diagnostic System Check: Testing

  1. Turn ignition off. Connect scan tool. Turn ignition on. Attempt to establish communication with BCM. If scan tool communicates with BCM, go to next step. If scan tool does not communicate with BCM, go to step 3).
  2. Using scan tool, check for BCM DTCs. If any DTC exists, go to BCM DTC DEFINITION  and perform appropriate test. If no DTCs exist, system is operating properly.
  3. Attempt to establish communication with other systems connected to same serial data line (PCM, EBCM, etc.). If scan tool communicates with other systems, go to next step. If scan tool does not communicate with other systems, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DATA LINE  .
  4. Using test light, backprobe between ABS-BCM fuse (located in instrument panel fuse block) and ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 9).
  5. Turn ignition off. Disconnect BCM 10-pin connector C3. Using test light, backprobe between ground and BCM harness connector C3 terminal "B" (Orange wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
  6. Using test light, backprobe between battery voltage and BCM harness connector C3 terminal "D" (Black wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 12).
  7. Using DVOM, check for continuity in Light Green and Purple wires between BCM 24-pin connector C2 terminal B5 and Data Link Connector (DLC) terminal No. 2. If continuity exists, go to step 13). If continuity does not exist, go to step 10).
  8. Turn ignition off. Replace BCM. See REMOVAL & INSTALLATION  . Reprogram BCM. See BCM PROGRAMMING. Go to step 2).
  9. If fuse is blown, repair short to ground in Orange wire between BCM connector C3 and instrument panel fuse block. If fuse is okay, repair poor connection or open in Orange wire. Turn ignition on. Using scan tool, attempt to establish communication with BCM. If scan tool communicates with BCM, go to step 2). If scan tool does not communicate with BCM, go to step 5).
  10. Repair poor connection or open in Light Green or Purple wire between BCM connector C2, splice pack SP205 and DLC. Turn ignition off. Reinstall all components or connectors. Turn ignition on. Attempt to establish communication with BCM. If scan tool communicates with BCM, go to step 2). If scan tool does not communicate with BCM, go to step 13).
  11. Repair poor connection or open in Orange wire between BCM connector C3 and instrument panel fuse block. Turn ignition off. Reinstall all components or connectors. Turn ignition on. Attempt to establish communication with BCM. If scan tool communicates with BCM, go to step 2). If scan tool does not communicate with BCM, go to step 6).
  12. Repair poor connection or open in Black wire between BCM connector C3 and ground. Turn ignition off. Reinstall all components or connectors. Turn ignition on. Attempt to establish communication with BCM. If scan tool communicates with BCM, go to step 2). If scan tool does not communicate with BCM, go to step 7).
  13. Turn ignition on. Using test light, backprobe between ground and BCM 32-pin connector C1 terminal C12 (Pink wire). If test light illuminates, go to step 8). If test light does not illuminate, go to next step.
  14. Connect test light between ground and underhood electrical center connector C2 terminal D2 (Pink wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 16).
  15. Repair poor connection or open in Pink wire between BCM connector C1 and underhood electrical center connector C2. Turn ignition off. Reinstall all components or connectors. Turn ignition on. Attempt to establish communication with BCM. If scan tool communicates with BCM, go to step 2). If scan tool does not communicate with BCM, go to step 8).
  16. Connect test light between ground and underhood electrical center connector C2 terminal C2 (Pink wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 18).
  17. Replace underhood electrical center. Turn ignition off. Reinstall all components or connectors. Turn ignition on. Attempt to establish communication with BCM. If scan tool communicates with BCM, go to step 2). If scan tool does not communicate with BCM, go to step 8).
  18. Check PCM-BCM fuse No. 439 (10-amp), located in instrument panel fuse block. If fuse is okay, go to next step. If fuse is blown, go to step 20).
  19. Repair poor connection or open in Pink wire between underhood electrical center connector C2 and instrument panel fuse block. Turn ignition off. Reinstall all components or connectors. Turn ignition on. Attempt to establish communication with BCM. If scan tool communicates with BCM, go to step 2). If scan tool does not communicate with BCM, go to step 8).
  20. Replace PCM-BCM fuse. Turn ignition off. Reinstall all components or connectors. Turn ignition on. Attempt to establish communication with BCM. If scan tool communicates with BCM, go to step 2). If scan tool does not communicate with BCM, go to step 8).
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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