Circuit Description
The electronic brake control module (EBCM) receives several inputs from the steering wheel position sensor. Three digital square wave signal inputs are wired directly to the EBCM harness connector, however, only signals A and B are used or monitored. The failure of the index pulse signal does not effect vehicle stability enhancement system (VSES) function. The body control module (BCM), which receives an analog steering position sensor input, transmits steering position data on the serial data line. The EBCM 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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0455 Front Steering Position Sensor Circuit
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The VSES sensors have been successfully initialized. Refer to ABS Description and Operation for a complete explanation of VSES sensor initialization. |
Conditions for Setting the DTC
Any of the following conditions may cause the DTC to set:
| • | The steering angle calculated by the EBCM does not correlate with the steering angle information which is being transmitted on the serial data line. |
| • | When driven forward in a straight line, the centered steering angle differs by more than 30 degrees from the centered steering angle when the sensors are initialized. |
| • | The EBCM detects an erratic signal from steering wheel position signal A or signal B. |
| • | 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 EBCM, which causes the DTC to set. |
| • | The EBCM detects an open or shorted steering wheel position signal A or signal B, after having received a valid signal during the same ignition. |
Action Taken When the DTC Sets
| • | The EBCM disables the VSES. |
| • | The message center displays the service stability system message. |
Conditions for Clearing the DTC
The condition for setting the DTC is no longer present and you use the scan tool Clear DTCs function.
Diagnostic Aids
| • | DTC C0455 may be falsely set if you did not turn OFF the ignition for 5 seconds after clearing DTCs from the EBCM. This is why all diagnostic tables which apply to this system always instruct you to turn OFF the ignition for 5 seconds after clearing DTCs. If this DTC has set after you cleared DTCs from the EBCM, or used the scan tool to clear all DTCs from all modules, and you did not cycle the ignition afterward, it is likely that no actual malfunction exists. |
| • | Whenever any one of the steering signals to the EBCM is lost, the scan tool displays a fixed steering wheel position, which indicates the last known steering wheel position. This can aid you in diagnosing an intermittent malfunction. |
| • | If the DTC does not reset during step 2 or 3 of the diagnostic procedure, the stability system disabled message may be displayed due to an unsuccessful initalization. This occurs if the EBCM does not receive any signal from one or both of the digital inputs during the entire ignition cycle. If this occurs, refer to Stability System Disabled Indicator Always On for further diagnosis. |
| • | Inspect the vehicle for proper wheel alignment. Ensure the vehicle does not pull toward the left or right while driving straight forward on a level surface. |
| • | Communicate with the customer to determine the conditions under which the message center displays the service stability system message. Learning the conditions under which the DTC sets may help you duplicate the failure. |
| • | Use the Snapshot function on the scan tool in order to assist you in locating an intermittent malfunction. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics or Power Distribution Schematics and Ground Distribution Schematics Connector End View Reference: Antilock Brake System Connector End Views and Suspension Controls Connector End Views | ||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||
|
Important: Center the steering wheel before proceeding with this step. Do not rotate the steering wheel while performing this step.
Does the DTC set? | -- | Go to DTC C0472 or C0473 | Go to Step 3 | |||||||||||
3 | Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text. Does the DTC set? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||||
4 |
Does the scan tool display an Steering Wheel Sensor Signal within the specified range? | 2.3-2.7 V | Go to Step 5 | Go to Step 9 | ||||||||||
5 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 6 | ||||||||||
6 | Test the battery positive voltage circuit to the steering wheel position sensor for an intermittent open. Refer to Testing for Electrical Intermittents and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 7 | ||||||||||
7 | Test both of the steering wheel position sensor ground circuits for an intermittent open. Refer to Testing for Electrical Intermittents and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8 | ||||||||||
8 | Inspect for poor connections at the harness connector of the steering wheel position sensor and at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 | ||||||||||
9 | 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 10 | -- | ||||||||||
10 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||||||
