C0455

DTC C0455





Test 1-5





Test 6-17





Test 18-25

Circuit Description
The steering wheel position sensor inputs to the rear wheel steering control module consists of 3 digital input circuits, phase A, phase B. and index marker pulse and 1 analog signal circuit. The analog signal is a class 2 message from the TBC. The steering wheel position sensor supply voltage is between 4.05.1 volts.
Phase A and phase B circuits are digital pulse signals whose output represents one degree of steering wheel rotation. When observing the phase A data and the phase B data parameters on the scan tool, the parameters will not have the same value at the same time. When the steering wheel is rotated, the phase A data and the phase B data parameters will be shown as high or low on the scan tool.
The marker pulse is a digital pulse that is displayed as high on the scan tool for 20° only when the steering wheel angle is between -10 and +10°.
Steering wheel position sensor, analog signal, voltage is at or near 2.5 volts with the wheels at center voltage increases/decreases for less than 1 full turn (± 225°) then plateaus for remainder of wheel travel. The body control module (BCM), which receives an analog steering position sensor input, transmits steering position data on the serial data line. The rear wheel steering control module monitors the serial data information as an added fail-safe for the steering position sensor circuitry. Battery voltage is supplied to the digital portion of the steering wheel position sensor from the cruise control fuse. The analog portion of the steering wheel position sensor is supplied a 5-volt reference from the BCM. This circuit is also used for a lamp dimming function.

Conditions for running the DTC
Turn ON the ignition, with engine ON.

Conditions for Setting the DTC
^ The marker pulse data parameter is high for less than 20° of the steering wheel angle.
^ The marker pulse data parameter is high for greater than 20° of the steering wheel angle.
^ The marker pulse data parameter is high when the steering wheel angle parameter is greater than +90°.
^ The marker pulse data parameter is high when the steering wheel angle parameter is less than -90 degrees.
^ The steering wheel sensor analog output voltage is less than 0.125 volts.
^ The steering wheel sensor analog output voltage is greater than 4.875 volts.
^ The steering wheel position sensor phase A circuit is shorted to ground, open or shorted to voltage
^ The steering wheel position sensor phase B circuit is shorted to ground, open or shorted to voltage.
^ The BCM detects an invalid steering wheel position sensor signal, sets a DTC, and therefore, cannot transmit valid serial data information. The BCM sends a serial data message to the RWSCM, which causes the DTC to set.

Action Taken When the DTC Sets
^ The Service 4 Wheel Steer indicator in IPC will be displayed.
^ The code is displayed on the scan tool as DTC C0455.
^ The output to the motor is ramped down slowly, at a rate of 2° per second to 0° and held.
^ The rear wheels will be returned to the centered position.

Conditions for Clearing the DTC
^ Conditions for DTC are not currently present.
^ The module receives a clear code command from the scan tool.
^ The DTC clears after 100 malfunction free ignition cycles.

Diagnostic Aids
The following conditions are possible causes:
^ A class 2 communication problem with the TBC.
^ The steering wheel was rotated with the steering gear disconnected.
^ A malfunctioning steering wheel position sensor is present.
^ A steering wheel position sensor circuit is open.
^ A steering wheel position sensor circuit was shorted.
Perform an inspection of the wiring and of the connectors. Failure to carefully inspect the wiring and the connectors may result in misdiagnosis. Misdiagnosis causes part replacement with reappearance of the malfunction.

Steering Wheel Position Sensor - Digital Signal
^ 3 outputs used (Phase A, Phase B, Index Pulse)
^ Phase A & Phase B
Offset PWM wave forms created when turning the wheel
^ Index pulse
Signal is present only when steering wheel is within 10 degrees either side of center
Output is used to determine Direction of Rotation and Rate of Rotation





Steering Wheel Position Sensor - Digital Signal





Steering Wheel Position Sensor - A and B Phase





Steering Wheel Position Sensor - Analog Signal

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step will help determine if the 5 volt reference circuit is open.
4. This step will help determine if the sensor return circuit is open.
5. Test for the proper operation of the phase A circuit.
7. Test for the proper operation of the phase B circuit.
9. Test for the proper operation of the marker pulse circuit.
11. Test for the proper operation of the sensor signal circuit.
14. Test for a short to ground in the 5 volt reference circuit.