• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Lateral Accelerometer 5 volt Reference Circuit | C0196 00 | C0196 00 | C0196 00 | -- |
Lateral Accelerometer Signal Circuit | C0196 00 | C0196 00 | C0196 00 | C0196 1A, C0196 09, C0196 52 |
Lateral Accelerometer Low Reference Circuit | -- | C0196 00 | -- | -- |
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 vehicles yaw motion by applying differential braking to the left or right front wheel.
The amount of differential braking applied to the left or right front wheel is based on both the yaw rate error and side slip rate error. The side slip rate error is a function of the lateral acceleration minus the product of the yaw rate and vehicle speed. The yaw rate error and side slip rate error are combined to produce the total delta velocity error. When the delta velocity error becomes too large and the VSES system activates, the drivers steering inputs combined with the differential braking will attempt to bring the delta velocity error toward zero.
The VSES activations generally occur during aggressive driving, in the turns or bumpy roads without much use of the accelerator pedal. When braking during VSES activation, the brake pedal will feel different than the antilock brake system (ABS) pedal pulsation. The brake pedal pulsates at a higher frequency during VSES activation.
• | The ignition is ON. |
• | The ignition voltage is greater than 8 volts. |
• | The vehicle is stopped or the vehicle speed is greater than 45 km/h (28 mph). |
• | The ignition is ON. |
• | The ignition voltage is greater than 8 volts. |
• | The ignition is ON. |
• | The ignition voltage is greater than 8 volts. |
• | The yaw rate isolation test runs with any of the following conditions: |
- | The brake pedal is not pressed. |
- | ABS is not active. |
- | The vehicle speed is greater than 8 km/h (5 mph). |
- | The lateral accelerometer signal is less than 4.9 m/s² (0.5 g). |
- | VSES is not active on undriven axle and traction control system (TCS) is active. |
One of the following conditions exist:
• | The yaw rate signal voltage is less than 0.15 volt. |
• | The yaw rate signal voltage is greater than 4.85 volts for 1 second. |
The yaw rate sensor changes by greater than 390 degrees/second per second.
The yaw rate bias exceeds 7 degrees/second.
The yaw rate error is greater than 5 degrees/second 30 times in one drive cycle.
• | The EBCM disables the VSES for the duration of the ignition cycle. |
• | The driver information center (DIC) displays the SERVICE STABILITRAK message. |
• | The ABS/TCS remains functional. |
• | The condition for the DTC is no longer present and the DTC is cleared with a scan tool. |
• | The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Inspect the vehicle for proper steering alignment.
Antilock Brake System Schematics
Control Module References for Scan Tool Information
⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the EBCM. |
⇒ | If less than the specified range, test the 5 volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM. |
⇒ | If greater than the specified range, test the 5 volt reference circuit for a short to voltage. If the circuit tests normal, replace the EBCM. |
⇒ | If greater than the specified range, test the yaw rate sensor signal circuit terminal C for a short to voltage. If the circuit tests normal, replace the EBCM. |
⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the EBCM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for EBCM replacement, setup, and programming |