Antilock Brake System
DTC C0870
Circuit Description
The brake pressure sensor reference voltage is monitored for an over or under voltage condition.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0870 Device Voltage Reference Output {single or 1} Circuit
Conditions for Running the DTC
* The ignition is ON.
* The vehicle speed is greater than 40 km/h (25 mph).
Conditions for Setting the DTC
A malfunction is detected if the supply voltage is above 5.6 volts or below 4.4 volts for more than 60 milliseconds.
Action Taken When the DTC Sets
* A malfunction DTC is set.
* The ABS, traction control system (TCS) and vehicle stability enhancement system (VSES) are disabled.
* The ABS, SERVICE VEHICLE SOON and Stability Off lamp indicators are ON.
Conditions for Clearing the DTC
* The condition for the DTC is no longer present.
* A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
* Using a scan tool
* The electronic brake control module (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 the following conditions:
* An open in the pressure sensor supply voltage circuit
* A short to ground in the pressure sensor supply voltage circuit
* A short to B+ in the pressure sensor supply voltage circuit
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step tests for specified voltage on the brake pressure signal circuit.
3. This step checks to see if the brake pressure signal circuit voltage was below specified voltage.
4. This step checks to see if the brake pressure signal circuit voltage was above specified voltage.
5. This step tests for a short to ground in the 5-volt reference circuit of the brake pressure sensor.
6. This step tests for a short to voltage in the 5-volt reference circuit of the brake pressure sensor.
7. This step tests for a high resistance or an open in the ground circuit of the brake pressure sensor.
8. This step checks the brake pressure sensor connector for poor connections.
9. This step checks the EBCM connector for poor connections.
