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 21 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.
The EHPS connector has an interlock consisting of pins 18 and 19. This interlock serves to prohibit the power steering pump from operating in any ignition key position other than ACC or ON.
DTC Descriptor
This diagnostic supports the following DTC:
DTC C0448 Electric Hydraulic Steering Pump Enable Circuit
Conditions for Running the DTC
| • | EHPS module in RUN mode. |
| • | Ignition switch in ACC or ON position. |
| • | Battery voltage between 12-58 volts. |
Conditions for Setting the DTC
| • | The circuit defined by pins 18 and 19 on the 24-way signal connector is open and the EHPS detects the discrete accessory or ignition make ups. |
| • | Connector C2 is not fully seated. |
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. |
| • | EHPS module operation is normal, but the electric motor control is inactive. |
| • | Stores DTC C0448 in the powertrain control module (PCM). |
| • | History DTC C0448 will be set in PCM. |
Conditions for Clearing the DTC
| • | The interlock loop between pins 18 and 19 is re-established. |
| • | 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.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Power Steering Schematics Connector End Views Reference: Power Steering Connector End Views | |||
1 | Did you perform the Vehicle Diagnostic System Check? | Go to Step 2 | |
Is there continuity in the circuit? | Go to Step 4 | Go to Step 3 | |
Repair shorting link in C2 connector. Refer to Connector Repairs . Did you complete the repair? | Go to Step 5 | -- | |
4 |
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 repair? | Go to Step 5 | -- |
5 |
Does DTC C0448 reset? | Go to Step 2 | System OK |
