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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 P1482 >> 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 for the ability of the PCM to control cooling fan clutch speed. If answer to question is Yes, ensure to refer to all Diagnostic Aids.
  5. 6:  Verifies the ignition 1 voltage circuit of the cooling fan relay.
DTC P1482

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 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 17 
5 
  1. Install a scan tool.
  2. Start the engine.
  3. Observe the Fan Speed parameter in the powertrain control module Output Controls.
  4. With a scan tool, command the fan speed to increase.
Does the Fan Speed increase?		 - Go to Diagnostic Aids Go to Step 6 
6 
  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 a good ground.
Does the test lamp illuminate?		 - Go to Step 7  Go to Step 11 
7 Test the cooling fan clutch control circuit of the cooling fan relay for a short to voltage or an open. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 19  Go to Step 8 
8 Test the cooling fan clutch control circuit of the cooling fan relay for a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 19  Go to Step 9 
9
  1. Connect a test lamp to the cooling fan clutch control circuit of the cooling fan relay and ground.
  2. Connect a digital multimeter (DMM) to the test lamp probe and ground.
  3. Set the DMM to A/C range and select frequency.
  4. Start the engine.
  5. Verify that the Fan Control is commanded to 0%.
Is the frequency less than the specified value?		 OL Go to Step 14  Go to Step 10 
10 Command the Fan Control to 100%.
Does the frequency fluctuate?		 - Go to Step 13  Go to Step 14 
11 Inspect the Eng Fan fuse.
Is the fuse open?		 - Go to Step 12  Go to Step 15 
12 Test the cooling fan clutch control circuit of the cooling fan relay for a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 19  Go to Step 15 
13 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 19  Go to Step 16 
14 Inspect for poor connections at the harness connector of the PCM. 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 19  Go to Step 18 
15 Repair the ignition 1 voltage circuit of the cooling fan relay. Refer to WIRING REPAIRS in Wiring Systems.
Did you complete the repair?		 - Go to Step 19  -
16 Replace the cooling fan relay.
Did you complete the replacement?		 - Go to Step 19  -
17 Replace the cooling fan clutch. Refer to Fan Clutch Replacement .
Did you complete the replacement?		 - Go to Step 19  -
18
IMPORTANT: Perform the programming procedure for the PCM.
Replace the PCM. Refer to POWERTRAIN CONTROL MODULE .Did you complete the replacement?		 - Go to Step 19  -
19
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 - Go to Step 2  System OK
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