C0481
DTC C0481
Circuit Description
The electro-hydraulic power steering (EHPS) operates when voltage at the EHPS connector is in the range of 34 - 50 volts. The EHPS will go into standby mode if the supply voltage at the EHPS connector drops below 18 volts for more than 10 milliseconds. The EHPS module shall be turned back ON once the supply voltage rises above 22 volts, without a key cycle being required. If the supply voltage drops below 12 volts, the EHPS module drivers shall shut down and a key cycle will be required to reset. The EHPS module shall withstand voltages up to a transient voltage of 58 volts for 400 milliseconds. If the supply voltage exceeds 55 volts, the EHPS module drives shall shut down and a key cycle will be required to reset. The 36 volts power supply is grounded directly to the negative terminal of the EHPS.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0481 Electric Hydraulic Steering Motor Circuit Range/Performance
Conditions for Running the DTC
^ The EHPS module is in RUN mode.
^ The ignition switch is in the ACC or ON position.
^ Battery voltage between 12 - 58 volts.
Conditions for Setting the DTC
The EHPS module commands the electric motor to operate at a set speed, but the output sensed by the hall-effect sensor is equal to zero.
Action Taken When the DTC Sets
^ System operation is reduced.
^ The SERVICE BRAKE SYSTEM message and SERVICE STEER SYSTEM message will be displayed.
^ A chime will sound.
^ The EHPS module operation is normal, but the electric motor control is inactive.
^ Stores DTC C0481 in the powertrain control module (PCM).
^ History DTC C0481 will be set in the PCM.
Conditions for Clearing the DTC
^ The EHPS module can detect the proper motor RPM.
^ Using the scan tool
^ A history DTC will clear after 255 consecutive ignition cycles if the condition for the malfunction is no longer present.
Diagnostic Aids
It may be necessary to check Testing for Intermittent Conditions and Poor Connections.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step checks for 2,500 RPM that was set with the scan tool.
3. This step checks for motor current at 2,500 RPM.
4. This step checks for the EHPS demand parameter percentage.
5. This step checks if the motor speed is more than 2,500 RPM.
6. This step checks if the motor speed is steady.
7. This step checks for the EHPS demand parameter percentage.
8. This step checks for motor current.
