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Home >> Pontiac >> 2000 >> Firebird Base, 2D Convertible, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P1637: Charging System Light Control Circuit (Grand PRIX) >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . After performing OBD system check, go to next step.
  2. Check instrument cluster system. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Repair as necessary. After repairs, go to next step.
  3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, with engine off. Check voltage between ground and affected PCM output circuit at PCM harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step  7.
  4. Set DVOM to 10-amp scale. Check current between ground and affected PCM output circuit. Observe reading for about 2 minutes. If current reading is 0.05-1.50 amps, go to step  12. If current reading is not 0.05-1.50 amps, go to next step.
  5. Disconnect instrument panel cluster harness connector. Leave PCM disconnected. Check voltage between ground and affected PCM output circuit. If voltage reading is zero volts, go to step  15. If voltage reading is not zero volts, go to next step.
  6. Repair short to voltage in affected PCM output circuit. After repairs, go to step  17.
  7. Check ignition feed fuse for instrument panel cluster indicator lights. If fuse is open, go to next step. If fuse is okay, go to step  9.
  8. Repair short to ground in ignition feed circuit for instrument cluster indicator lights. Repair as necessary. Replace fuse. After repairs, go to step  17.
  9. Turn ignition off. Disconnect instrument panel cluster harness connector. Turn ignition on, with engine off. Check voltage between ground and ignition feed circuit for instrument panel cluster indicator lights. If voltage reading is about battery voltage, go to next step. If voltage reading is not about battery voltage, go to step  14.
  10. Check affected PCM output circuit for an open or short to ground. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to next step.
  11. Check affected PCM output circuit and ignition feed circuit for poor connection at instrument panel cluster and PCM. Repair as necessary. After repairs, go to step  17. If connections are okay, go to step  15.
  12. Turn ignition off. Reconnect PCM connector. Disconnect instrument panel cluster connector. Turn ignition on, with engine off. Connect a test light between affected PCM output circuit and ignition feed circuit at instrument panel cluster harness connector. Using scan tool in OUTPUTS TEST function, cycle affected indicator light on and off. If test light flashes on and off, see DIAGNOSTIC AIDS . If test light does not flash on and off, go to next step.
  13. Check affected PCM output circuit for poor connection at PCM. Repair as necessary. After repairs, go to step  17. If connection is okay, go to step  16.
  14. Repair open in ignition feed circuit to instrument panel cluster indicator lights. After repairs, go to step  17.
  15. Replace instrument panel cluster. After replacing cluster, go to step  17.
  16. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  17. Using scan tool, clear DTCs. Operate vehicle within conditions for setting this DTC. If DTC resets, repeat step  2. If DTC does not reset, system is okay.
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