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Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. 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 checks for 2,500 RPM that was set with the scan tool.
  2. 3:  This step checks for motor current at 2,500 RPM.
  3. 4:  This step checks for the EHPS demand parameter percentage.
  4. 5:  This step checks if the motor speed is more than 2,500 RPM.
  5. 6:  This step checks if the motor speed is steady.
  6. 7:  This step checks for the EHPS demand parameter percentage.
  7. 8:  This step checks for motor current.
DTC C0481

Step Action Value(s) Yes No
Schematic Reference: Power Steering System Schematics 
Connector End Views Reference: Power Steering System Connector End Views 
1 Did you perform the electro-hydraulic power steering (EHPS) Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Power Steering System 
2 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine ON.
  3. With a scan tool, set the EHPS Demand Speed to 2,500 RPM.
  4. Observe the EHPS Motor RPM parameter on the scan tool data list.
Does the EHPS Motor RPM parameter value match what was set?		 2,500 RPM Go to Step 3  Go to Step 5 
3  With a scan tool, observe the EHPS Motor Current parameter on the data list.
Is the Motor Current parameter less than the specified value?		 15 A Go to Step 4  Go to Step 11 
4  With a scan tool, observe the EHPS Demand parameter on the data list.
Is the EHPS Demand parameter less than the specified value?		 50 percent Go to Diagnostic Aids Go to Step 11 
5  With a scan tool, observe the EHPS Motor RPM parameter on the data list.
Is the EHPS Motor RPM parameter greater than the specified value?		 2,500 RPM Go to Step 6  Go to Step 7 
6  With a scan tool, observe the EHPS Motor RPM parameter value on the data list.
Is the motor speed steady?		 - Go to Step 10  Go to Step 9 
7  With a scan tool, observe the EHPS Demand parameter value on the data list.
Is the EHPS Demand parameter greater than the specified value?		 50 percent Go to Step 8  Go to Step 9 
8  With a scan tool, observe the EHPS Motor Current parameter value on the data list.
Is the EHPS Motor Current parameter greater than the specified value?		 15 A Go to Step 11  Go to Step 12 
9
  1. Reload the calibration. Refer to Service Programming System (SPS) in Programming.
  2. Use the scan tool to perform the Pump Motor Test function in Scan Tool Output Controls to reset motor RPM.
Have the procedures been completed?		 - Go to Step 13  -
10 Reprogram the EHPS module. Refer to Service Programming System (SPS) in Programming.
Has procedure been completed?		 - Go to Step 13  -
11 Repair hydraulic system.
Did you complete hydraulic system repair?		 - Go to Step 13  -
12
IMPORTANT: Always perform the calibration procedure for the brake pedal position (BPP) sensor. Refer to Brake Pedal Position Sensor Calibration Description and Operation .
Replace the EHPS powerpack. Refer to Power Steering Pump Replacement (4.3L) Power Steering Pump Replacement (4.8L, 5.3L and 6.0L) Power Steering Pump Replacement (8.1L) Power Steering Pump Replacement (6.6L Diesel) Power Steering Pump Replacement (Parallel Hybrid Truck) .Has the replacement been completed?		 - Go to Step 13  -
13
  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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