C1284

Circuit Description
The Vehicle Stability Enhancement System (VSES) uses the lateral accelerometer input when calculating the desired yaw rate. The usable output voltage range for the lateral accelerometer is 0.25 - 4.75 volts. The scan tool will report zero lateral acceleration as 2.5 volts with no sensor bias present.
The lateral accelerometer sensor bias compensates for sensor mounting alignment errors and electronic signal errors.

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 lateral accelerometer sensor bias test runs with the ignition ON.
2. The lateral accelerometer sensor self test runs with the following conditions:
^ The ignition is ON.
^ The vehicle is stopped.
3. The lateral accelerometer sensor jerk test runs with the ignition ON.
4. The centered lateral accelerometer sensor test runs with the following conditions:
^ The ignition is ON.
^ The vehicle is stopped.
5. The lateral accelerometer sensor isolation test runs with the following conditions:
^ The ignition is ON.
^ DTC C1282 is not set.
^ The yaw rate is less than 8 degrees/second.
6. The above lateral accelerometer sensor isolation test run 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 compensated bias value of the lateral accelerometer sensor is greater than 0.3 9.
2. The lateral accelerometer sensor performs a self test that results in an offset of 0.59. The EBCM compares the sensor output during the self test with the output following the test. The DTC sets when the lateral acceleration immediately following the self test is 0.8 9.
3. The lateral jerk is greater than 19 g/second for 0.01 seconds.
4. The lateral acceleration is 0.4 9 for 0.25 seconds.
5. The side slip error is greater than 4.9 meters/second*second 30 times within a drive cycle.
6. The side slip error is greater than 4.9 meters/second*second for 5 seconds. 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 ABS/TCS 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

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.