Antilock Brake System

DTC C0870

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.

DTC Descriptor
DTC C0870
- Voltage Reference Output 1 Circuit

Circuit/System Description

The steering wheel speed position sensor and the yaw rate and lateral acceleration sensor reference voltages are monitored for an over or under voltage condition.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

When the electronic brake control module (EBCM) detects the supply voltage is above 5.6 volts or below 4.4 volts for more than 60 milliseconds for the steering wheel speed position sensor or the yaw rate and lateral acceleration sensor.

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 DTC will be current for as long as the fault is present.
* When the fault is no longer present, the DTC will be a history DTC.
* A history DTC will clear after 100 ignition cycles.

Reference Information
Schematic Reference

Antilock Brake System Schematics ([1][2]Antilock Brakes / Traction Control Systems)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

ABS Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate sensor.
2. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal and ground for the sensor listed below:

* Steering wheel speed position sensor 5-volt reference circuit terminal 1.
* Yaw rate and lateral acceleration sensor 5-volt reference circuit B.

• If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
• If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the EBCM.

3. If all circuits test normal, replace the appropriate sensor.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement (Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement)
* Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for EBCM replacement, setup, and programming