Antilock Brake System
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.
2. This step tests for a short to ground or voltage on the 5-volt reference circuit.
3. This step tests for an internal short to ground in the yaw rate and lateral accelerometer sensor.
4. This step tests for an internal short to ground in the SWPS.
