Circuit Description
Stabilitrak® is activated by the EBTCM calculating the desired yaw rate and comparing it 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 EBTCM will attempt to correct the vehicle's yaw motion by applying differential braking to the left or right front wheel.
Conditions for Setting the DTC
One of the following conditions occur:
| • | During Stabilitrak® activation, the analog and digital steering sensor inputs do not agree for 1 second. |
| • | During Stabilitrak® activation, the estimated and actual yaw rates do not agree for 5 seconds. |
| • | The EBTCM checks for this DTC after the steering angle has been centered, during Stabilitrak® activation, and when the vehicle does not have lateral acceleration. The DTC sets when the yaw rate error does not change for 10 seconds. |
| • | In most cases, DTCs C1284-C1287 will set this DTC. |
| • | Normal conditions which could cause this DTC to set include Stabilitrak® activations brought on by aggressive driving on extremely slippery road surfaces. For example, spinning the vehicle in one direction for more than 10 seconds. |
Action Taken When the DTC Sets
| • | A malfunction DTC is stored. |
| • | Stabilitrak® is disabled. |
| • | The DIC displays the SERVICE STABILITY SYS message. |
| • | The ABS/TCS remain functional. |
Conditions for Clearing the DTC
| • | The condition for DTC is no longer present and you used scan tool Clear DTCs function. |
| • | The condition for DTC is no longer present and you used the On-Board Clear DTCs function. |
| • | The EBTCM does not detect the DTC in 50 drive cycles. |
Diagnostic Aids
| • | Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a flat 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. |
| • | Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction. |
| • | Poor connections, broken insulation, or a break in the wire inside the insulation may cause an intermittent malfunction. |
| • | If an intermittent malfunction exists, refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
| • | The Snapshot function on the scan tool can help find an intermittent DTC. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
2 |
Are DTCs C1221-C1235 or C1282-C1288 present? | -- | Go to Step 3 | |
3 | Using the scan tool, perform the Steering Wheel Position Sensor Test. Refer to Scan Tool Diagnostics . Is the analog and digital display on the scan tool within ±5 degrees of each other at the center (zero) position? | -- | Go to Step 5 | Go to Step 4 |
4 | Replace the steering wheel position sensor (SWPS). Refer to Lower Steering Shaft, Lower Bearing, Column Jacket - Off Vehicle in Steering Wheel and Column - Tilt. Did you complete the repair? | -- | Go to Step 7 | -- |
5 |
Is the voltage within the specified range? | 2.3-2.7 V | Go to Step 7 | Go to Step 6 |
6 | Replace the yaw rate sensor. Refer to Vehicle Yaw Sensor Replacement . Did you complete the repair? | -- | Go to Step 7 | -- |
7 | Perform the Diagnostic Test Drive. Refer to Diagnostic Test Drive . Did DTC C1281 set as a current DTC? | -- | Go to Step 8 | Go to Diagnostic System Check |
8 | Replace the EBTCM. Refer to Electronic Brake Control Module Replacement . Did you complete the repair? | -- | Go to Diagnostic System Check | -- |
