Circuit Description
The electro-hydraulic power steering (EHPS) system uses the Phase A and Phase B signal inputs from the steering wheel sensor that are 90 degrees out of phase to provide quadrature pulsed data corresponding to steering shaft rotational displacement and direction. The signal is resolved to within one mechanical degree of resolution. The EHPS system monitors the steering wheel rate information from the steering wheel sensor every 5 milliseconds (200 Hz) for proper operation.
DTC Descriptor
This diagnostic supports the following DTC:
DTC C0544 Steering Position Sensor Data Error
Conditions for Running the DTC
| • | EHPS module in RUN mode. |
| • | Ignition switch in ACC or ON position. |
| • | Battery voltage between 12-58 volts. |
| • | Vehicle speed greater than 10 km/h (6.21 mph). |
Conditions for Setting the DTC
| • | Steering wheel sensor position never changes for 60 seconds when vehicle speed greater than 10 km/h (6.21 mph). |
| • | Connector C2 is not fully seated. |
| • | Towing vehicle may set DTC. |
| • | Operating vehicle on a hoist. |
Action Taken When the DTC Sets
| • | System operation is reduced. |
| • | The SERVICE STEER SYSTEM message will be displayed. |
| • | Ramp the motor speed input to the commanded flow resolved from a default steering wheel rate. |
| • | Stores a DTC C0544 in the powertrain control module (PCM). |
| • | History DTC C0544 will be set in PCM. |
Conditions for Clearing the DTC
| • | A single pulse of steering wheel movement is detected by the EHPS module. |
| • | 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
| • | Ignition cycling is not necessary for allowing EHPS system to operate normally. |
| • | 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.
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Checks to see if DTC resets.
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Tests the steering wheel position sensor phase A and phase B circuits for an open or short to ground.
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Checks for poor connections at the harness connector of the steering wheel position sensor connector.
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Checks for poor connections at the harness connector of the EHPS module connector.
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Checks to see if DTC resets.
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 | |
Does the DTC reset? | Go to Step 3 | Go to Diagnostic Aids | |
Did you find and correct the condition? | Go to Step 9 | Go to Step 4 | |
Inspect for poor connections at the harness connector of the steering wheel position sensor connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 5 | |
Inspect for poor connections at the harness connector of the EHPS module connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 6 | |
6 |
Important: Perform the Learn Alignment procedure. Refer to Wheel Alignment Measurement. Replace the steering wheel position sensor. Refer to Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement . Did you complete the replacement? | Go to Step 7 | -- |
Does DTC C0544 reset? | Go to Step 8 | -- | |
8 |
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 9 | -- |
9 |
Does DTC C0544 reset? | Go to Step 2 | System OK |
