Circuit Description
The rear wheel steering module provides the current that activates the rear wheel steering motor actuator control circuits. Phase A , phase B, and phase C are the input circuits to the steering gear motor assembly. In its active state, the output current is pulse width modulated with up to 85 amps at 12 volts, with a normal range of 20-50 amps. When the rear wheel steering control module does not see the rear wheel steering gear motor respond to the current inputs properly the rear wheel steering control module will set a DTC C0538.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0538 Rear Steering Motor Circuit
Conditions for Running the DTC
The fault is detected when the engine is ON.
Conditions for Setting the DTC
| • | Rear steering motor circuits short to positive battery voltage |
| • | Rear steering motor circuits short to ground |
| • | Rear steering motor circuits open |
Action Taken When the DTC Sets
| • | The Service 4 Wheel Steer indicator in instrument panel cluster (IPC) will be displayed. |
| • | The code is displayed on the scan tool as DTC C0538. |
| • | The output command to the motor is zeroed. The motor drive circuits are disabled using commands to open the power relay and to close the motor shorting relay. |
| • | Rear wheels returned to the centered position. |
Conditions for Clearing the DTC
| • | The conditions for the DTC are not currently present. |
| • | The rear wheel steering control module receives a clear code command from the scan tool. |
| • | The history DTC clears after 100 malfunction free ignition cycles. |
Diagnostic Aids
| • | Inspect for poor connections at the harness connector of the rear wheel steering control module and inspect the wiring harness. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems. |
| • | Observe the rear wheel steering mode select switch. If all of the mode indicator LEDs are illuminated the rear wheel steering control module has lost its memory settings and the scan tool must be used to re-calibrate the rear wheel steering alignment data in the rear wheel steering control module. Refer to Wheel Alignment Measurement in Wheel Alignments. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Rear Wheel Steering Schematics Connector End View Reference: Rear Wheel Steering Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
With a scan tool, monitor the DTC Information DTC C0538 in the rear wheel steering module. Does the scan tool indicate that DTC C0538 is current? | -- | Go to Step 3 | Go to Diagnostic Aids | |
3 |
Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 4 |
4 |
Does the DTC reset? | -- | Go to Step 5 | Go to Step 6 |
5 | Replace the rear wheel steering module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 6 | |
6 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
