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Home >> Pontiac >> 2000 >> Firebird Formula, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 5.7L >> Diagnostic Tests >> DTC P0480: Cooling Fan Relay No. 1 Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command cooling fan relay No. 1 on and off. If relay turns on and off as commanded, go to next step. If relay does not turn on or off when commanded, go to step  5.
  3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a DVOM set to 10-amp scale, check current from relay control circuit in PCM harness connector to ground for 2 minutes. If current draw is less than 0.75 amp (but not zero), see DIAGNOSTIC AIDS . If current draw is not as specified, go to next step.
  4. Turn ignition off. Disconnect cooling fan relay No. 1. Check resistance from relay control circuit in PCM harness connector to ground. If resistance is infinite, go to step  12. If resistance is not infinite, go to step  10.
  5. Turn ignition off. Disconnect cooling fan relay No. 1. Connect test light between relay coil terminals in relay harness connector. Turn ignition on. Using scan tool, command relay on and off. If test light turns on and off with each command, go to step  8. If test light does not turn on and off with each command, go to next step.
  6. Connect test light to ground and probe ignition feed circuit in cooling fan relay No. 1 harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  11.
  7. Turn ignition off. Reconnect cooling fan relay No. 1. Disconnect PCM harness connector containing relay control circuit. Turn ignition on. Connect a fused jumper wire between ground and PCM connector (harness side) relay control circuit. If relay operates, go to step  9. If relay does not operate, go to step  10.
  8. Check connections at cooling fan relay No. 1. Repair as necessary. After repairs, go to step  14. If relay connection is okay, go to step  12.
  9. Check connections at PCM. Repair as necessary. After repairs, go to step  14. If connections are okay, go to step  13.
  10. Repair faulty cooling fan relay No. 1 control circuit. After repairs, go to step  14.
  11. Repair faulty cooling fan relay No. 1 ignition feed circuit. After repairs, go to step  14.
  12. Replace cooling fan relay No. 1. After replacing relay, go to step  14.
  13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  14. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step  2.
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.
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