C1282

Circuit Description
The Vehicle Stability Enhancement System (VSES) is activated by the 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's yaw motion by applying differential braking to the left or right front wheel.
The amount of differential braking applied to the left or right front wheel is based on both the yaw rate error and side slip rate error. The side slip rate error is a function of the lateral acceleration minus the product of the yaw rate and vehicle speed. The yaw rate error and sideslip rate error are combined to produce the total delta velocity error. When the delta velocity error becomes too large and the VSES system activates, the driver's steering inputs combined with the differential braking will attempt to bring the delta velocity error toward zero.

Conditions for Running the DTC
The EBCM performs 6 different tests to detect a DTC condition. The numbers below correspond to the numbers in

Conditions for Setting the DTC.
1. The yaw rate sensor bias test runs with the ignition ON.
2. The yaw rate sensor acceleration test runs with the ignition ON.
3. The yaw rate sensor circuit test runs with the vehicle stopped or with the vehicle speed greater than 45 km/h (28 mph).
4. The yaw rate isolation test runs with the following conditions:
^ The brake pedal is not pressed.
^ The ABS is not active.
^ The vehicle speed is greater than 5 km/h (3 mph).
5. The above yaw rate isolation test run with the VSES active.
6. The false activation test runs with the VSES active.

Conditions for Setting the DTC
The EBCM performs 6 different tests to detect a DTC condition. The numbers below correspond to the numbers in

Conditions for Running the DTC.
1. The yaw rate bias is greater than 7 degrees/second.
2. The yaw rate input change is greater than 390 degrees/second/second.
3. The yaw rate input voltage is less than 0.15 volts or greater than 4.85 volts for 1 second.
4. The yaw rate error is greater than 10 degrees/second 30 times within a drive cycle.
5. The yaw rate error is greater than 10 degrees/second for 5 seconds. Under this condition, this DTC will set along with DTC C1281.
6. The yaw rate error is greater than 10 degrees/second with the vehicle speed less than 60 km/h (37 mph) and the acceleration pedal is pressed more than 25 percent of the pedal travel range for 1 second during the VSES activation. Under this condition, this DTC will set along with DTC C1281.

Action Taken When the DTC Sets
^ The EBCM disables the VSES for the duration of the ignition cycle.
^ The DIC displays the SERVICE STABILITY SYS message.
^ The ABSITCS remains functional.

Conditions for Clearing the DTC
^ The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
^ The condition for the DTC is no longer present (the DTC is not current) and you used the On-Board Diagnostics Clear DTC function.
^ The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
^ During diagnosis, park the vehicle on a level surface.
^ Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
^ Find out from the driver under what conditions the DTC was set (when the DIC displayed the SERVICE STABILITY SYS message). This information will help to duplicate the failure.
^ The Snapshot function on the scan tool can help find an intermittent DTC.

Test Description
The number below refers to the step number on the diagnostic table.
3. Tests for the proper operation of the circuit in the low voltage range.
4. Tests for the proper operation of the circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
5. Tests for a short to voltage in the 5 volt reference circuit.
6. Tests for a high resistance or an open in the ground circuit.