Circuit Description
The electronic brake control module (EBCM) supplies 5 volts to the yaw rate sensor/lateral accelerometer. When the vehicle is not moving, or is being driven in a stable, straight line, lateral acceleration is 0 m/sec/sec (0 ft/sec/sec) and the lateral accelerometer signal voltage is very near 2.5 volts. This is referred to as lateral accelerometer bias voltage. Making a turning maneuver causes the lateral accelerometer signal voltage to increase, or decrease, depending on the direction of the turn. The sharper the turn, the greater the change in signal voltage.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0186 Lateral Accelerometer Circuit
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The vehicle stability enhancement system (VSES) sensors have been successfully initialized or the message center has displayed the stability system disabled message due to an unsuccessful initialization attempt. Refer to ABS Description and Operation for a complete explanation of VSES sensor initialization. |
| • | The vehicle is being driven relatively straight and level at a speed greater than 11 km/h (7 mph), before performing a stable turning maneuver. |
Conditions for Setting the DTC
Any of the following conditions may cause the DTC to set:
| • | Open lateral accelerometer circuitry is detected. |
| • | Shorted lateral accelerometer circuitry is detected. |
| • | An erratic lateral accelerometer signal is detected. |
| • | The EBCM detects that the lateral accelerometer sensor signal does not correspond with signals from other sensors. |
Action Taken When the DTC Sets
| • | The EBCM disables the VSES. |
| • | The stability indicator turns ON. |
Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
Diagnostic Aids
| • | Inspect the vehicle for proper wheel alignment. Ensure the vehicle does not pull toward the left or right while driving straight forward on a level surface. |
| • | Communicate with the customer to determine the conditions under which the message center displays the Service Stability System message. Learning the conditions under which the DTC sets may help you duplicate the failure. |
| • | Use the Snapshot function on the scan tool in order to assist you in locating an intermittent malfunction. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the sensor 5 volt reference circuitry and ground circuit.
-
This step tests the sensor signal circuit for an open or high resistance.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
Important: If DTC C0292 is set, diagnose C0292 before proceeding with diagnostics for C0186. If DTC C0196 is set, diagnose C0196 before proceeding with diagnostics for C0186. Always use connector test adapters when performing tests to avoid damage to delicate connector terminals. Do not turn OFF the ignition during this diagnostic procedure unless the step in the table instructs you to do so. The scan tool may display some incorrect data if the ignition is cycled.Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | ||||||||||
1 | Did you perform the ABS Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||
2 |
Does the DTC reset? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||||
Does the voltage measure greater than the specified value? | 4.75 V | Go to Step 5 | Go to Step 4 | |||||||
Test the lateral accelerometer signal circuit for the following conditions:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | |||||||
5 |
Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | ||||||
6 | 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 9 | Go to Step 8 | ||||||
7 |
Important: Replace the lateral accelerometer/yaw rate sensor, Refer to EBCM reprogramming to verify current calibration (enabling Yaw Rate Sensor Recalibration). Use a scan tool to Recalibrate the Yaw Rate Sensor. Replace the lateral accelerometer/ yaw rate sensor. Refer to Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement in Computer/integrating Systems. Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
8 |
Important: Following EBCM replacement, perform the set-up procedure for the EBCM. Use the scan tool to perform the Tire Size Calibration procedure. Replace the EBCM. Refer to Control Module References . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
9 |
Does the DTC reset? | -- | Go to Step 3 | System OK | ||||||
