C1285

DTC C1284 or C1285

Test 1-9:

Test 10-16:

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's yaw motion by applying differential braking to the left or right front wheel.

Conditions for Running the DTC
The ignition is ON.

Conditions for Setting the DTC
C1284
The compensated bias value of the lateral accelerometer is greater than 0.3 g.

C1285
The lateral accelerometer input voltage is less than 0.15 volts or greater than 4.85 volts for 1 second.

Action Taken When the DTC Sets
^ The EBCM disables the VSES for the duration of the ignition cycle.
^ The DIC displays the Service Stability System message.
^ The ABS/TCS remains functional.

Conditions for Clearing the DTC
^ The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
^ The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
The following conditions can cause this concern:
^ Improper steering alignment.
^ Open, short to ground, or short to voltage.
^ Internal lateral accelerometer failure.
^ EBCM internal failure.

Test Description
The numbers below refer to the step numbers 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 the bias voltage of the lateral accelerometer sensor.