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 C0564 Program Read Only Memory (ROM) Checksum Error
Conditions for Running the DTC
| • | The EHPS module is in RUN mode. |
| • | The ignition switch is in the ACC or ON position. |
| • | Battery voltage is between 12-58 volts. |
Conditions for Setting the DTC
| • | The EHPS module cannot validate the checksum from a programming event (software checksum error). |
| • | A replacement EHPS powerpack has been installed and not programmed. |
Action Taken When the DTC Sets
| • | The SERVICE BRAKE SYSTEM message and SERVICE STEER SYSTEM message will be displayed. |
| • | A chime will sound. |
| • | The EHPS module operation is reduced and the electric motor control is inactive. |
| • | Stores DTC C0564 in the powertrain control module (PCM). |
| • | History DTC C0564 will be set in the PCM. |
Conditions for Clearing the DTC
| • | After a successful programming event |
| • | 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 perform the programming procedure more than once. |
| • | It may be necessary to check Testing for Intermittent Conditions and Poor Connections . |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Power Steering Schematics Connector End Views Reference: Power Steering Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
Does the DTC reset? | Go to Step 3 | System OK | |
3 |
Important: Always perform the calibration procedure for the brake pedal position (BPP) sensor. Refer to Brake Pedal Position Sensor Calibration . Replace the EHPS powerpack. Refer to Power Steering Pump Replacement . Did you complete the replacement? | Go to Step 4 | -- |
4 |
Does the DTC reset? | Go to Step 2 | System OK |
