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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1545 (Engine Cooling System -- 5.7L) >> Diagnostic Information and Procedures >> DTC P0481 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Chevrolet Corvette. 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:  Listen for an audible click when the coolfan 2 relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
  2. 3:  Tests for voltage at the coil side of the coolfan 2 relay. The coolfan 3 fuse supplies ignition 1 voltage to the coil side of the coolfan 2 relay.
  3. 4:  Verifies that the PCM is providing ground to the coolfan 2 relay.
  4. 5:  Tests if ground is constantly being applied to the coolfan 2 relay.
DTC P0481

Step Action 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. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the Fan Relays 1, 2 & 3 ON and OFF.
Does the coolfan 3 and the coolfan 2 relays turn ON and OFF with each command?		 Go to Diagnostic Aids Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the coolfan 2 relay
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the Ignition 1 Voltage circuit of the coolfan 2 relay with a test lamp that is connected to a good ground.
Does the test lamp illuminate?		 Go to Step 4  Go to Step 8 
4 
  1. Connect a test lamp between the control circuit of the coolfan 2 relay and the battery positive voltage circuit of the coolfan 2 relay.
  2. With a scan tool, command the Fan Relays 1, 2 & 3 ON and OFF.
Does the test lamp turn ON and OFF with each command?		 Go to Step 9  Go to Step 5 
5  Does the test lamp remain illuminated with each command? Go to Step 7  Go to Step 6 
6 Test the control circuit of the coolfan 3 relay and the coolfan 2 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 12  Go to Step 9 
7 Test the control circuit of the coolfan 3 relay and the coolfan 2 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 12  Go to Step 9 
8 Test the Ignition 1 Voltage circuit of the coolfan 3 relay and the coolfan 2 relay 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 12  Go to Step 10 
9 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 12  Go to Step 11 
10 Repair the coolfan motor supply voltage circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 12  -
11
IMPORTANT: Perform the set up procedure for the PCM.
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls.Did you complete the replacement?		 Go to Step 12  -
12
  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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