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HOMESERVICE MANUALSBUICK2000CENTURY CUSTOMREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - BASIC DIAGNOSTIC PROCEDURESNO START DIAGNOSISNO START - ENGINE CRANKS OKAY (2.4L)IGNITION CIRCUIT
2000 Buick Century Custom

Ignition Circuit

2000 Buick Century CustomSECTION Ignition Circuit
  1. Perform OBD system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
  2. Check for DTCs. If DTC P0601, P0602 or P1629 is present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
  3. Crank engine while monitoring CKP activity counter on scan tool. If counter increments, go to next step. If counter does not increment, go to step  9 .
  4. Turn ignition on. Using scan tool, command fuel pump on. If fuel pump runs, go to next step. If fuel pump does not run, see FUEL PUMP ELECTRICAL CIRCUIT  .
  5. Install fuel pressure gauge. See BASIC FUEL SYSTEM CHECKS  . Turn ignition on. If fuel pressure is 52-58 psi (3.7-4.1 kg/cm2 ), go to next step. If fuel pressure is not as specified, diagnose fuel system. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.
  6. Turn ignition off. Remove fuel pump relay located in underhood fuse/relay center. Remove ignition coil/control module assembly. Connect jumper wire between ground and ignition control module assembly. Install Spark Plug Jumper Wire Kit (J 36012-A). Install spark tester on No. 1 spark plug wire. Ground spark plug jumper wire No. 4 (companion cylinder). Crank engine. Repeat for each cylinder, ensuring companion cylinder spark plug jumper wire is grounded for each procedure. If spark is present for all cylinders, go to next step. If spark is not present for all cylinders, go to step  15 .
  7. Turn ignition off. Check for faulty spark plugs. Repair as necessary. After repairs, go to step  32 . If spark plugs are okay, go to next step.
  8. Check for basic engine mechanical problems. Repair as necessary. After repairs, go to step  32 . If no engine mechanical problems are found, go to step  27 .
  9. Turn ignition off. Disconnect ignition control module harness connector. Turn ignition on. Measure voltage between ignition control module ground circuit and ignition control module ignition feed circuit at harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step  23 .
  10. Measure voltage between battery ground and CKP sensor ground circuit at ignition control module harness connector. If voltage is present, go to step  25 . If voltage is not present, go to next step.
  11. Measure resistance between battery negative terminal and CKP sensor ground circuit at ignition control module harness connector. If resistance is infinite, go to next step. If resistance is not infinite, go to step  26 .
  12. Measure resistance between CKP sensor ground circuit and CKP sensor signal circuit at ignition control module harness connector. If resistance is 500-900 ohms, leave DVOM connected and go to next step. If resistance is not 500-900 ohms, go to step  18 .
  13. Set DVOM to AC scale. Crank engine. If AC voltage is greater than 200 mV, go to next step. If AC voltage is 200 mV or less, go to step  28 .
  14. Using test light connected to battery positive terminal, probe 7X reference signal circuit, and then probe reference low circuit at ignition control module harness connector while monitoring CKP activity counter on scan tool. If counter increments, go to step  19 . If counter does not increment, go to step  22 .
  15. Turn ignition off. Remove spark plug jumper wires. Remove ignition coil housing. Disconnect ignition coil connector from ignition control module. Turn ignition on. Measure voltage between ground and coil ignition positive voltage circuit at ignition coil connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step  19 .
  16. Connect test light between battery positive terminal and affected coil circuit at ignition control module. Crank engine. If test light flashes, go to step  24 . If test light does not flash, go to next step.
  17. Turn ignition off. Disconnect ignition control module harness connector. Connect DVOM between battery positive terminal and affected ignition control output circuit at ignition control module harness connector. If battery voltage is present, go to step  21 . If battery voltage is not present, go to step  20 .
  18. Check CKP sensor circuits for opens or poor connections. Repair as necessary. After repairs, go to step  32 . If circuits are okay, go to step  28 .
  19. Inspect ignition control module harness connector for poor connections. Repair as necessary. After repairs, go to step  32 . If connections are okay, go to step  29 .
  20. Check affected ignition control output circuit for an open or poor connection at PCM. Repair as necessary. After repairs, go to step  32 . If circuits are okay, go to step  31 .
  21. Check affected ignition control input circuit for open or poor connection at ignition control module. Repair as necessary. After repairs, go to step  32 . If circuit is okay, go to step  29 .
  22. Check 7X reference signal circuit for short to ground, short to voltage, open or poor connection. Repair as necessary. After repairs, go to step  32 . If circuit is okay, go to step  31 .
  23. Repair open in ignition control module ground circuit and/or ignition feed circuit. After repairs, go to step  32 .
  24. Check for open or short to ground in jumper harness between ignition control module and ignition coils. Repair as necessary. After repairs, go to step  32 . If jumper harness is okay, go to step  30 .
  25. Repair short to voltage in CKP sensor ground circuit. After repairs, go to step  32 .
  26. Repair short to ground in CKP sensor ground circuit. After repairs, go to step  32 .
  27. Check for the following:
    • Faulty PCM grounds.
    • Stuck TP sensor.
    • Skewed ECT sensor.
    • Skewed or unresponsive MAP sensor.
    • Loose CKP sensor.
    Repair as necessary. After repairs, go to step  32 .
  28. Replace CKP sensor. After repairs, go to step  32 .
  29. Replace ignition control module. After repairs, go to step  32 .
  30. Replace both ignition coils. After repairs, go to step  32 .
  31. Replace PCM. Perform PCM relearn procedures. After repairs, go to next step.
  32. Attempt to start engine. If engine runs, perform OBD system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. If engine does not run, go to step  2 .
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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.