GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 Terraza - 4WD 🢒 Brakes 🢒 Park Brake 🢒 DTC C0870

Circuit Description

The electronic brake control module (EBCM) supplies the 5-volt reference to the following sensors:

    • The steering wheel position sensor (SWPS)
    • The yaw rate and lateral acceleration sensor
    • The master cylinder brake pressure sensors internal to the EBCM

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0870 Device Voltage Reference Output (Single or 1) Circuit

Conditions for Running the DTC

Ignition voltage is greater than 8 volts.

Conditions for Setting the DTC

One or more of the following conditions are met:

    • When the EBCM commands the 5-volt reference ON, the output is less than 4.9 volts or greater than 5.1 volts.
    • When the EBCM commands the 5-volt reference OFF, the output is greater than 0.5 volt.

Action Taken When the DTC Sets

If equipped, the following actions will occur:

    • The EBCM disables the vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
    • The driver information center (DIC) displays the Service Stability System message.
    • The EBCM disables the traction control system (TCS) for the duration of the ignition cycle.
    • The DIC displays the Service Traction Control System message.

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

Multiple VSES DTCs can set if the 5-volt reference is shorted to ground or power.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests for a short to ground or voltage on the 5-volt reference circuit.

    2.

  2. This step tests for an internal short to ground in the yaw rate and lateral accelerometer sensor.

    3.

  3. This step tests for an internal short to ground in the SWPS.

Step

Action

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

Go to Diagnostic System Check - Vehicle

2

Check for a short to ground or voltage on the 5-volt reference circuit of the following sensors:

    • The yaw rate and lateral acceleration sensor
    • The steering wheel position sensor (SWPS)

Did you find and correct the condition?

Go to Step 8

Go to Step 3

3

  1. Clear the DTCs with the scan tool.
  2. Turn OFF the ignition.
  3. Disconnect the yaw rate and lateral acceleration sensor.
  4. Turn ON the ignition.

Does DTC C0870 set?

Go to Step 4

Go to Step 5

4

  1. Reconnect the yaw rate and lateral acceleration sensor.
  2. Clear the DTCs with the scan tool.
  3. Turn OFF the ignition.
  4. Disconnect the SWPS.
  5. Turn ON the ignition.

Does DTC C0870 set?

Go to Step 7

Go to Step 6

5

Replace the yaw rate and lateral acceleration sensor. Refer to Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement .

Did you complete the replacement?

Go to Step 8

--

6

Replace the SWPS. Refer to Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement .

Did you complete the replacement?

Go to Step 8

--

7

Replace the electronic brake control module (EBCM). Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 8

--

8
  1. Clear the DTCs using the scan tool.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK