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.

Condition for Running the DTC
The EBCM performs 2 different tests to detect a DTC condition. The number below corresponds to the number in Condition for Setting the DTC.
1. The lateral accelerometer self test is run at initialization. The output of the sensor will be offset by a large fixed amount for a short period of time after ignition power is first applied to the EBCM. The test will run under the following conditions:
- The ignition is ON.
- A114 wheel speeds are 0 km/h (0 mph).
- The steer angle is within 90 degrees of centered.
- The period of time between 0.23 seconds and 0.28 seconds after ignition power is first applied to the EBCM.

2. The lateral accelerometer bias test is run with the ignition ON.

Condition for Setting the DTC
One of the following conditions occurs:
1. The lateral accelerometer signal does not increase by 0.4 g above the normal signal level.
2. The compensated bias value of the lateral accelerometer is greater than 0.3 g.

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 50 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 final on intermittent DTC.