GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • 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.

DTC Descriptors

DTC C0186 00: Lateral Accelerometer Circuit Electrical Failure

DTC C0186 5A: Lateral Accelerometer Circuit Erratic

DTC C0186 3B: Lateral Accelerometer Self Test Failure

DTC C0186 1A: Lateral Accelerometer Offset Failure

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Lateral Accelerometer Supply Voltage Circuit

C0186 00

C0186 00

C0186 00

--

Lateral Accelerometer CAN Bus High Circuit

C0186 00

C0186 00

C0186 00

C0186 5A, 3B, 1A

Lateral Accelerometer CAN Bus Low Circuit

C0186 00

C0186 00

C0186 00

C0186 5A, 3B, 1A

Lateral Accelerometer Ground Circuit

--

C0186 00

--

--

Circuit/System Description

The lateral accelerometer and the yaw rate sensors are combined into one sensor external to the electronic brake control module (EBCM). The vehicle stability enhancement system (VSES) uses the lateral accelerometer input when calculating the desired yaw rate. The usable output signal is a serial data CAN circuits.

Conditions for Running the DTC

The ignition switch is in the ON position.

Conditions for Setting the DTC

    • The yaw/lateral combination sensor reports an internal failure.
    • The yaw/lateral combination sensor learns a wrong offset value.
    • Incorrectly mounted yaw/lateral sensor.

Action Taken When the DTC Sets

One or more of the following actions may occur:

    • VSES are disabled.
    • The VSES indicator iluminates
    • The driver information center (DIC) displays the Service ESC message.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

Possible causes of this DTC are as follows:

    • Incorrectly mounted yaw/lateral sensor
    • Internal failure in the yaw/lateral sensor
    • Intermittent wiring connections

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation Reference

ABS Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs
    •  Connector Repairs

Scan Tool Reference

Control Module References for Scan Tool Information

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the Yaw Rate/Lateral Accelerometer sensor.
  2. Test for less than 1 ohm of resistance between the low reference circuit terminal 5 and ground.
  3. If greater than the specified range, test for an open/high resistance in the low reference circuit . If the circuit tests normal, replace the EBCM.
  4. Ignition ON, test for ignition voltage between the ignition circuit terminal 3 and the low reference circuit terminal 5.
  5. If not the specified value, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
  6. Ignition OFF, disconnect the harness connector at the EBCM.
  7. Test for infinite resistance between the low reference circuit terminal 29 and ground.
  8. If greater than the specified value, test the low reference circuit for a short to ground.
  9. Ignition ON, test for 0 volts between the communication circuit terminal 18 and ground at the EBCM harness connector.
  10. If greater than the specified value, test the communication circuit for a short to voltage.
  11. Test for 0 volts between the communication circuit terminal 19 and ground.
  12. If greater than the specified value, test the communication circuit for a short to voltage.
  13. Ignition OFF, test for infinite resistance between the communication circuit terminal 18 and ground.
  14. If not the specified value, test the communication circuit for a short to ground.
  15. Test for infinite resistance between the communication circuit terminal 19 and ground.
  16. If not the specified value, test the communication circuit for a short to ground.
  17. Test for less than 1 ohm of resistance between the communication circuit terminals 18 and terminal 2.
  18. If greater than the specified range, test the communication circuit for an open/high resistance.
  19. Test for less than 1 ohm of resistance between the communication circuit terminals 19 and terminal 1.
  20. If greater than the specified range, test the communication circuit for an open/high resistance.
  21. Test for infinite resistance between the communication circuit 18 and the communication circuit 19.
  22. If not the specified value, test the communication circuits for a short together.
  23. If all circuits test normal, replace the Yaw Rate/Lateral sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Vehicle Yaw Sensor Replacement
    •  Control Module References for EBCM replacement, setup and programming