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HOMESERVICE MANUALSBUICK2000CENTURY CUSTOMREPAIR AND DIAGNOSISBRAKESTRACTION CONTROLANTI-LOCK BRAKE SYSTEM WITH TRACTION CONTROL SYSTEM - DELPHI 7SYMPTOM TESTSTEST A: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE IN DATA LINK COMMUNICATIONS
2000 Buick Century Custom

Test A: Scan Tool Does Not Communicate With Class 2 Device In Data Link Communications

2000 Buick Century CustomSECTION Test A: Scan Tool Does Not Communicate With Class 2 Device In Data Link Communications
  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  under DIAGNOSIS & TESTING. After performing diagnostic system check, go to next step.
  2. Turn ignition off. Install scan tool. Turn ignition on, with engine off. Attempt to establish communication with other modules on the class 2 serial data line, such as PCM. If scan tool communicates with any other modules on the class 2 serial data line, go to next step. If scan tool does not communicate with any other modules, diagnose data link system circuit. See WIRING DIAGRAMS  .
  3. Turn ignition off. Disconnect EBCM harness connector. Connect Universal Pinout Box (J 39700) using the Cable Adapter (J 39700-99) to EBCM harness connector only. Check voltage from pinout box battery supply circuit to a good ground. If voltage reading is within battery voltage, go to next step. If voltage reading is not within battery voltage, go to step  7 .
  4. Check ignition positive voltage input circuit for EBCM. If voltage reading is about battery voltage, go to next step. If voltage reading is not within battery voltage, go to step  8 .
  5. Check for open in module ground circuit. Repair as necessary. After repairs, go to step  20 . If circuit is okay, go to next step.
  6. Check serial data line circuit for an open between EBCM connector and splice. See WIRING DIAGRAMS  . Repair as necessary. After repairs, go to step  20 . If circuit is okay, go to step  15 .
  7. Check fusible link (Gray) located near starter. If fusible link is okay, go to step  9 . If fusible link is okay, go to step  14 .
  8. Check ABS /PCM fuse located in the instrument panel fuse block. If fuse is okay, go to step  10 . If fuse is open, go to step  13 .
  9. Check voltage at fusible link (Gray) by probing between starter terminal and a good ground. If battery voltage is present, go to step  12 . If battery voltage is not present, go to step  17 .
  10. Install fuses, if removed. Turn ignition on, with engine off. Check voltage at instrument panel fuse block by probing between fuse test terminals and a good ground. If battery voltage is present, go to next step. If battery voltage is not present, go to step  16 .
  11. Repair open in ignition positive voltage circuit. After repairs, go to step  20 .
  12. Repair open in battery positive voltage circuit. After repairs, go to step  20 .
  13. Turn ignition on. Remove ABS/PCM fuse from instrument panel fuse block. Disconnect EBCM harness connector. Connect Universal Pinout Box (J 39700) using Cable Adapter (J 39700-99) to EBCM harness connector only. Check ignition voltage circuit for short to ground. Repair as necessary. After repairs, go to step  20 . If circuit is okay, go to step  15 .
  14. Turn ignition off. Disconnect battery negative cable. Remove fusible link (Gray) from starter connection. Disconnect EBCM harness connector. Connect Universal Pinout Box (J 39700) using Cable Adapter (J 39700-99) to EBCM harness connector only. Check battery voltage circuit for short to ground. Repair as necessary. After repairs, go to step  20 . If circuit is okay, go to next step.
  15. Check for poor connections at EBCM harness connector. Repair as necessary. After repairs, go to step  20 . If connections are okay, go to step  18 .
  16. Check for poor connections at instrument panel harness connector. Repair as necessary. After repairs, go to step  20 . If connections are okay, go to step  19 .
  17. Repair poor connection at starter terminal connector. After repairs, go to step  20 .
  18. Replace EBCM. After replacing EBCM, go to step  20 .
  19. Replace instrument panel. After replacing instrument panel, go to next step.
  20. Using scan tool, clear DTCs. Recheck DTCs. If DTC resets, go to step  2 . If DTC does not reset, system is okay.
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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.