Circuit Description
The vehicle stability enhancement system (VSES) is activated by the electronic brake control module (EBCM) calculating the desired yaw rate and comparing it to the actual yaw rate input. The desired yaw rate is calculated from measured steering wheel position, vehicle speed, and lateral acceleration. The difference between the desired yaw rate and actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes too large, the EBCM will attempt to correct the vehicle yaw motion by applying differential braking to the left or right front wheel.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Perform the Steering Position Sensor Test in order to verify if the steering wheel position sensor (SWPS) is operating properly.
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Verify that the lateral accelerometer input parameter is within the valid range.
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Verify that the yaw rate input parameter is within the valid range.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics | ||||||||
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | |||||
2 |
Did the scan tool display Yes within the specified value? | 30 seconds | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | ||||
With the scan tool, perform the Steering Position Sensor Test. Did the SWPS pass the test? | -- | Go to Step 4 | Go to Step 7 | |||||
With a scan tool, observe the Lateral Accelerometer Input parameter in the VSES data list. Does the scan tool display within the specified range? | 2.3-2.7 V | Go to Step 5 | Go to Step 8 | |||||
With a scan tool, observe the Yaw Rate Sensor Input parameter in the VSES data list. Does the scan tool display within the specified range? | 2.3-2.7 V | Go to Step 6 | Go to Step 9 | |||||
6 |
Important: Perform the setup procedure for the EBCM. An unprogrammed EBCM will result
in the following conditions:
Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the repair? | -- | Go to Step 10 | -- | ||||
7 | Replace the steering wheel position sensor (SWPS). Refer to Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement in Steering Wheel and Column. Did you complete the replacement? | -- | Go to Step 10 | -- | ||||
8 | Replace the lateral accelerometer sensor. Refer to Lateral Accelerometer Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||
9 | Replace the yaw rate sensor. Refer to Vehicle Yaw Sensor Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||
10 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 | ||||
