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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1949 (Engine Cooling System) >> Diagnostic Information and Procedures >> DTC P0480 or P0481 (LE5) >> Circuit/System Testing (LE5)

Circuit/System Testing (LE5)

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the 3 cooling fan relays listed below.
    • FAN AUX relay
    • FAN CNTRL relay
    • FAN main relay
  2. Ignition ON, verify that a test lamp illuminates between ground and the appropriate battery voltage circuit terminal 85.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  3. Verify that a test lamp does not illuminate between terminal 85 and terminal 86 of each relay.
    • If the test lamp illuminates, test the control circuit for a short to ground. If the circuit test normal, replace the ECM.
  4. Remove the test lamp.
  5. Ignition ON, command the affected relay ON using a scan tool. Verify the affected scan tool FC Relay Control Ckt. Short Volts Test Status Parameter is OK.
    • For the FAN AUX relay, use the scan tool Fan Relay 1 command.
    • For the FAN CNTRL and FAN MAIN relays, use the scan tool Relay 2 and 3 command.
    • If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  6. Install a 3A fused jumper wire between terminal 86 and terminal 85. Command the affected relay ON with a scan tool. Verify the scan tool Relay Control Ckt Short Volts Test Status Parameter is Fault.
    • If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  7. If all circuits and the ECM test normal, replace the affected relay.
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