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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1776 (Engine Cooling System) >> Diagnostic Information and Procedures >> DTC P1484 >> Test Description

Test Description

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.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step ensures that the DTC has failed this ignition cycle. If the scan tool displays Passed, then the answer is No.
  2. 3:  The cooling fan noise should increase as the cooling fan clutch engages. It can take up to 2 minutes for full cooling fan clutch engagement. If cooling fan clutch is previously fully engaged, then there will not be a noticeable change in cooling fan noise. Compare noise to a known good vehicle. If fan noise is louder than the known good vehicle, then answer Yes.
  3. 4:  In the previous step the cooling fan clutch was fully engaged. This step tests to ensure that the cooling fan clutch will disengage. A noticeable noise difference should be heard between a fully engaged cooling fan clutch and a disengaged cooling fan clutch. The cooling fan clutch is completely disengaged when the excessive fan noise is not heard.
  4. 5:  Tests the PCM's ability to control the cooling fan. If answer to question is Yes, ensure to refer to all Diagnostic Aids.
  5. 6:  Inspect for a mechanical condition which causes the DTC to set.
  6. 7:  Tests for voltage on the cooling fan clutch supply voltage circuit of the cooling fan clutch. The cooling fan clutch connector is a seal connector. You must use jumper wires for testing or damage to wiring or connector could happen.
  7. 8:  Tests the cooling fan relay for a PWM signal on the cooling fan clutch supply voltage circuit of the cooling fan clutch.
DTC P1484

Step Action Values Yes No
Schematic Reference: Engine Cooling Schematics 
Connector End View Reference:  Cooling System Connector End Views  
1 Did you perform the Engine Cooling Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Engine Cooling 
2 
  1. With a scan tool, observe the Powertrain DTC list.
  2. Start the engine.
  3. Operate the vehicle within the Conditions for Running in the DTC.
Does the scan tool indicate the DTC Failed this ignition cycle?		 - Go to Step 5  Go to Step 3 
3 
IMPORTANT: DTC P1482, for 4.2l (LL8) will set when the cooling fan relay is disconnected.
  1. Turn OFF the ignition.
  2. Disconnect the coolant fan relay.
  3. 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.
  4. Start the engine.
  5. Raise engine speed to 2000 RPM for 2 minutes.
Does the cooling fan engage?		 - Go to Step 4  Go to Step 5 
4 
IMPORTANT: Continuously excessive fan noise is due to the PCM commanding the cooling fan to 100% 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.
  1. Turn OFF the ignition.
  2. Remove the 10 amp fused jumper wire.
  3. Install cooling fan relay.
  4. Disconnect the cooling fan clutch connector.
  5. Start the engine.
  6. Raise engine speed to 2000 RPM for 2 minutes.
Does the cooling fan clutch disengage?		 - Go to Step 5  Go to Step 18 
5 
  1. Install a scan tool.
  2. Start the engine.
  3. With a scan tool, observe the Fan Speed and the Desired Fan Speed parameters in the powertrain control module Output Controls.
  4. Command the cooling fan clutch to 100%.
  5. Operate the engine at 2000 RPM for 2 minutes.
Is the Desired Fan Speed within the specified speed of the Fan Speed?		 1000 RPM Go to Diagnostic Aids Go to Step 6 
6 
  1. Turn OFF the ignition.
  2. 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
  3. If the above conditions exist, refer to one of the following procedures:
Did you find and correct the condition?		 - Go to Step 20  Go to Step 7 
7 
  1. Disconnect the cooling fan clutch connector at the fan shroud.
  2. Connect a jumper wire between each of the cooling fan clutch circuits.
  3. Connect a digital multimeter (DMM) between the clutch supply voltage circuit of the cooling fan clutch and ground.
  4. Start the engine.
  5. Command the Fan Control to 0%.
Does the voltage measure greater than the specified value?		 0.16 V Go to Step 10  Go to Step 8 
8  Command the fan control to 100%.
Does the voltage fluctuate?		 - Go to Step 11  Go to Step 9 
9
  1. Turn OFF the ignition.
  2. Disconnect the cooling fan relay.
  3. Turn ON the ignition, with the engine OFF.
  4. 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?		 - Go to Step 12  Go to Step 17 
10 Disconnect the cooling fan relay.
Does the voltage measure greater than the specified value?		 0.16 V Go to Step 14  Go to Step 11 
11 Test the cooling fan clutch ground for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 16 
12 Test the ground circuit of the cooling fan relay for an open or a high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 13 
13 Test the clutch supply voltage circuit of the cooling fan clutch for an open or a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 15 
14 Test the clutch supply voltage circuit of the cooling fan clutch for a short to voltage. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  -
15 Inspect for poor connections at the cooling fan relay. Refer to TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS and CONNECTOR REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 19 
16 Inspect for poor connections at the harness connector of the cooling fan clutch. Refer to TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS and CONNECTOR REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 18 
17 Repair the ignition 1 voltage circuit of the cooling fan relay. Refer to WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  -
18 Replace the cooling fan clutch. Refer to Fan Clutch Replacement .
Did you complete the replacement?		 - Go to Step 20  -
19 Replace the cooling fan relay.
Did you complete the replacement?		 - Go to Step 20  -
20
IMPORTANT: Follow this procedure in order to clear DTC P1484 after making a repair.
  1. Use the Clear DTC Information function of the scan tool.
  2. Perform an ignition key cycle.
  3. Operate the vehicle within the Conditions for Running in the DTC.
Does the DTC reset?		 - Go to Step 2  System OK
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