DTC C1286 Steering/Lateral Accelerometer Sensor Bias Malfunction w/JL4
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.
Conditions for Running the DTC
The steer angle has been centered.
Conditions for Setting the DTC
The steering sensor bias moves greater than 20 degrees after steer centering was accomplished.
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.
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This step performs the Steering Position Sensor Test to see if the steering wheel position sensor is operating properly.
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This step tests to see if the lateral accelerometer input parameter is within the valid range.
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This step tests to see if the yaw rate input parameter is within the valid range.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | |
Did the steering wheel position sensor (SWPS) pass the test? | -- | Go to Step 3 | Go to Step 7 | |
With the scan tool, observe the Lateral Accelerometer Input parameter in the Delco/Bosch ABS/TCS ICCS2 data list. Does the scan tool display within the specified range? | 2.3-2.7 V | Go to Step 4 | Go to Step 8 | |
With the scan tool, observe the Yaw Rate Input parameter in the Delco/Bosch ABS/TCS ICCS2 data list. Does the scan tool display within the specified range? | 2.3-2.7 V | Go to Step 5 | Go to Step 9 | |
5 |
Does the DTC reset? | -- | Go to Step 6 | Go to Diagnostic Aids |
6 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- |
7 | Replace the steering wheel position sensor (SWPS). Refer to Steering Shaft, Lower Bearing, and Jacket - Disassemble - Off Vehicle and Steering Shaft, Lower Bearing, and Jacket - Assemble - Off Vehicle in Steering Wheel and Column - Tilt. Did you complete the replacement? | -- | Go to Step 10 | -- |
8 | Replace the lateral accelerometer sensor. Refer to Lateral Accelerometer Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- |
9 | Replace the yaw rate sensor. Refer to Vehicle Yaw Sensor Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- |
10 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
