C1287

Circuit Description
The steering wheel position sensor supplies 1 analog input and 2 digital inputs, Phase A and Phase B. to the EBCM. By interpreting the relationship between the inputs, the EBCM can determine the position of the steering wheel and the direction of steering wheel rotation.
Steer angle centering is the process by which the EBCM calibrates the steering sensor output so that the output reads zero when the steering wheel is centered. Using the yaw rate input, lateral accelerometer input, and wheel speed sensor inputs, the initial steering center position is calculated after driving greater than 10 km/h (6 mph) for more than 10 seconds in a straight line on a level surface.

Condition for Running the DTC
The EBCM performs 3 different tests to detect a DTC condition. The numbers below correspond to the numbers in Condition for Setting the DTC.
1. The steer sensor rate test runs with the ignition ON.
2. The steer sensor analog mismatch test runs under the following conditions:
- The digital steer rate is less than 10 degrees/second.
- The absolute value of the analog steer angle is less than 135 degrees.
3. The analog cross-comparison test runs under the following conditions:
- The VSES is active.
- The digital steer rate is less than 1 0 degrees/second.

Condition for Setting the DTC
One of the following conditions occur:
1. The steer rate (speed that the steering wheel appears to be turning) is greater than 1000 degrees/second.
2. The difference between the analog steer angle and digital steer angle is greater than 20 degrees continuously for 5 seconds.
3. The difference between the analog steer angle and digital steer angle is greater than 20 degrees for 1 second. 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 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 find an intermittent DTC.

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 for a high resistance or an open in the ground circuit.