For 1990-2009 cars

### 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 the 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 number below refers to the step number on the diagnostic table.

1. Perform the Steering Position Sensor Test in order to verify if the steering wheel position sensor (SWPS) is operating properly.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Antilock Brake System Schematics
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Inspect the mounting of the yaw rate sensor/lateral accelerometer. Refer to Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 3
3 |

1. Install a scan tool.
2. Start the engine.
3. With a scan tool, observe the Yaw Rate Sensor Input parameter in the VSES data list.
4. Perform the Diagnostic Test Drive. Refer to Diagnostic Test Drive .

Does the scan tool display suddenly increase or decrease without rapid turning of the vehicle?

--

Go to Step 4

Go to Step 5

4 | Perform the diagnosis for DTC C0196. Refer to DTC C0196 . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12
5 |

1. Straighten the front wheels.
2. Observe the Dual Analog SWPS Input A and Dual Analog SWPS Input B in the DRP/ABS/TCS data list.
3. Slowly rotate the steering wheel in both directions.

Does the scan tool display change states as the steering wheel was rotated?

--

Go to Step 6

Go to Step 14

6 | With the scan tool, perform the Steering Position Sensor Test. Did the steering wheel position sensor (SWPS) pass the test? | -- | Go to Step 7 | Go to Step 14
7 |

1. Place the vehicle on a level surface.
2. With a scan tool, observe the Lateral Accelerometer Input parameter in the VSES data list.

Does the scan tool display within the specified range?

2.3-2.7V

Go to Step 9

Go to Step 8

8 | Replace the yaw rate sensor/lateral accelerometer. Refer to Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 9
9 | Inspect the electronic brake control module (EBCM) for the proper part number. Did you find the correct part number? | -- | Go to Step 10 | Go to Step 12
10 | Inspect the power steering gear for the proper part number. Did you find the correct part number? | -- | Go to Step 11 | Go to Step 13
11 | Inspect the alignment of the vehicle. Refer to Wheel Alignment Measurement . Did you find and correct the condition? | -- | Go to Step 15 | Go to Testing for Intermittent Conditions and Poor Connections
12 | Replace the EBCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | -- | Go to Step 15 | --
13 | Replace the power steering gear. Refer to Steering Gear Replacement . Did you complete the replacement? | -- | Go to Step 15 | --
14 | Replace the SWPS. Did you complete the repair? | -- | Go to Step 15 | --
15 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2