Circuit Description
The vehicle stability enhancement system (VSES) is activated by the electronic brake control mdoule (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.
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 ABS pedal pulsation. The brake pedal pulsates at a higher frequency during VSES activation.
DTC Descriptors
This diagnostic procedure supports the following DTC:
DTC C0186 Lateral Accelerometer Circuit
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .
DTC Symptom | DTC Symptom Descriptor |
|---|---|
00 | No Additional Information |
08 | Signal Invalid |
09 | Rate of Change Above Threshold |
19 | Signal Amplitude Above Maximum |
1A | Bias Level Out Of Range |
52 | Compare Failure |
Conditions for Running the DTC
C0186 00, 09, and 1A
| • | The ignition is ON. |
| • | The ignition voltage is greater than 8 volts. |
C0186 08
| • | The ignition is ON. |
| • | The ignition voltage is greater than 8 volts. |
| • | The vehicle speed is greater than 0 km/h (0 mph). |
C0186 19
| • | The ignition is ON. |
| • | The ignition voltage is greater than 8 volts. |
| • | The vehicle is stopped. |
C0186 52
| • | The ignition is ON. |
| • | The ignition voltage is greater than 8 volts. |
| • | DTC C0196 is not set. |
| • | The yaw rate is less than 8 degrees per second. |
Conditions for Setting the DTC
C0186 00
One of the following conditions exist:
| • | The lateral accelerometer sensor input voltage is less than 0.15 volts. |
| • | The lateral accelerometer sensor input voltage is greater than 4.85 volts for 0.03 seconds. |
C0186 08
The lateral accelerometer voltage does not increase at least 0.5 volts during the lateral accelerometer sensor self test.
C0186 09
The lateral jerk exceeds 11 g per second twice within 0.2 seconds.
C0186 19
The lateral acceleration is greater than 0.5 g for more than 1 second.
C0186 1A
Both of the following conditions exist:
| • | The compensated bias value of the lateral accelerometer sensor is greater than 0.3 g. |
| • | The yaw rate is centered. |
C0186 52
The slip rate error exceeds 0.5 g 60 times within one drive cycle.
Action Taken When the DTC Sets
| • | The EBCM disables the VSES for the duration of the ignition cycle. |
| • | The DIC displays the Service Stabilitrak 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 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.
-
Tests for the proper operation of the circuit in the low voltage range.
-
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.
-
Tests for a short to voltage in the 5-volt reference circuit.
-
Tests the bias voltage of the yaw rate/lateral accelerometer sensor.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||
2 |
Does the scan tool display that the Lateral Accelerometer Signal parameter is within the specified range? | 0.15-4.85 V | Go to Step 6 | Go to Step 3 | ||||||
Does the scan tool display that the Lateral Accelerometer Signal parameter is less than the specified value? | 0.15 V | Go to Step 4 | Go to Step 10 | |||||||
Does the scan tool display that the Lateral Accelerometer Signal parameter is greater than the specified value? | 4.85 V | Go to Step 5 | Go to Step 8 | |||||||
Does the voltage measure less the specified value? | 5.1 V | Go to Step 12 | Go to Step 7 | |||||||
Does the scan tool display that the Lateral Accelerometer Signal parameter is within the specified range? | 2.3-2.7 V | Go to Diagnostic Aids | Go to Step 11 | |||||||
7 | Test the 5-volt reference circuit of the yaw rate/lateral accelerometer sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 | ||||||
8 | Test the 5-volt reference circuit of the yaw rate/lateral accelerometer sensor for the following conditions:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 9 | ||||||
9 | Test the signal circuit of the yaw rate/lateral accelerometer sensor for the following conditions:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 | ||||||
10 | Test the signal circuit of the yaw rate/lateral accelerometer sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 | ||||||
11 | Test the low reference circuit of the yaw rate/lateral accelerometer sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 | ||||||
12 | Inspect for poor connections at the harness connector of the yaw rate/lateral accelerometer sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 14 | ||||||
13 | Inspect for poor connections at the harness connector of the electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15 | ||||||
14 | Replace the yaw rate/lateral accelerometer sensor. Refer to Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||
15 | Replace the EBCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||
16 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
