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DTC P1484: Test

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Engine Cooling Diagnostic System Check? If so, go to next step. If not, go to DIAGNOSTIC SYSTEM CHECK - ENGINE COOLING  under SELF-DIAGNOSTIC SYSTEM.
  2. With a scan tool, observe the Powertrain DTC list. Start the engine. Operate the vehicle within the CONDITIONS FOR SETTING THE DTC  . Does the scan tool indicate the DTC Failed this ignition cycle? If so, go to step  5 . If not, go to next step.
    3. NOTE: DTC P1482 (on 4.2L) will set when the cooling fan relay is disconnected.
  3. Turn OFF the ignition. Disconnect the coolant fan relay. Connect a 10-amp fused jumper wire between the cooling fan clutch supply voltage circuit of the cooling fan and the ignition 3 voltage circuit of the cooling fan relay. Start the engine. Raise engine speed to 2000 RPM for 2 minutes. Does the cooling fan engage? If so, go to next step. If not, go to step  5 .
    4. NOTE: Continuously excessive fan noise is due to the PCM commanding the cooling fan to 100 percent engaged or a mechanical failure. If the fan noise decreases during this step, then this DTC is due to an electrical malfunction. Replacing the cooling fan clutch will not correct the condition.
  4. Turn OFF the ignition. Remove the 10-amp fused jumper wire. Install cooling fan relay. Disconnect the cooling fan clutch connector. Start the engine. Raise engine speed to 2000 RPM for 2 minutes. Does the cooling fan clutch disengage? If so, go to next step. If not, go to step  18 .
  5. Install a scan tool. Start the engine. With a scan tool, observe the Fan Speed and the Desired Fan Speed parameters in the powertrain control module Output Controls. Command the cooling fan clutch to 100 percent. Operate the engine at 2000 RPM for 2 minutes. Is the Desired Fan Speed within 1000 RPM of the Fan Speed? If so, go to DIAGNOSTIC AIDS  . If not, go to next step.
  6. Turn OFF the ignition. Inspect the cooling fan and the drive belt for the following conditions:
    • A cracked drive belt.
    • A loose or a worn drive belt.
    • A misrouted drive belt.
    • Oil leaks at the cooling fan clutch.
    • A free-spinning cooling fan.
    • A seized cooling fan clutch.
    • A broken cooling fan.

    If any of the conditions exist, repair as necessary. Did you find and correct the condition? If so, go to step  20 . If not, go to next step.

  7. Disconnect the cooling fan clutch connector at the fan shroud. Connect a jumper wire between each of the cooling fan clutch circuits. Connect a digital multimeter (DMM) between the clutch supply voltage circuit of the cooling fan clutch and ground. Start the engine. Command the Fan Control to zero percent. Does the voltage measure greater than 0.16 volt? If so, go to step  10 . If not, go to next step.
  8. Command the fan control to 100 percent. Does the voltage fluctuate? If so, go to step  11 . If not, go to next step.
  9. Turn OFF the ignition. Disconnect the cooling fan relay. Turn ON the ignition, with the engine OFF. Probe the ignition 1 voltage circuit of the cooling fan relay with a test lamp connected to a good ground. Does the test lamp illuminate? If so, go to step  12 . If not, go to step  17 .
  10. Disconnect the cooling fan relay. Does the voltage measure greater than 0.16 volt? If so, go to step  14 . If not, go to next step.
  11. Test the cooling fan clutch ground for an open. Did you find and correct the condition? If so, go to step  20 . If not, go to step  16 .
  12. Test the ground circuit of the cooling fan relay for an open or a high resistance. Did you find and correct the condition? If so, go to step  20 . If not, go to next step.
  13. Test the clutch supply voltage circuit of the cooling fan clutch for an open or a short to ground. Did you find and correct the condition? If so, go to step  20 . If not, go to step  15 .
  14. Test the clutch supply voltage circuit of the cooling fan clutch for a short to voltage. Did you find and correct the condition? If so, go to step  20 .
  15. Inspect for poor connections at the cooling fan relay. Did you find and correct the condition? If so, go to step  20 . If not, go to step  19 .
  16. Inspect for poor connections at the harness connector of the cooling fan clutch. Did you find and correct the condition? If so, go to step  20 . If not, go to step  18 .
  17. Repair the ignition 1 voltage circuit of the cooling fan relay. Did you find and correct the condition? If so, go to step  20 .
  18. Replace the cooling fan clutch. See FAN CLUTCH  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  20 .
  19. Replace the cooling fan relay. See COOLING FAN RELAY  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
    20. NOTE: Follow this procedure in order to clear DTC P1484 after making a repair.
  20. Use the Clear DTC Information function of the scan tool. Perform an ignition key cycle. Operate the vehicle within the CONDITIONS FOR RUNNING THE DTC  . Does the DTC reset? If so, go to step  2 . If not, system is OK.
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