Antilock Brake System - Non-Hybrid Greater than/Equal to 3900 kg (8600 lb) GVW
DTC C0870
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC C0870 00
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Device Voltage Reference Output Circuit
Diagnostic Fault Information
Circuit/System Description
The electronic brake control module (EBCM) supplies a 5 V reference and provides a low reference to the steering angle sensor. The EBCM monitors the steering angle sensor signal circuit to help determine the steering wheel position.
Conditions for Running the DTC
* The ignition is ON.
* Ignition voltage is greater than 9 V.
Conditions for Setting the DTC
* A short to voltage is detected in the steering angle sensor 5 V reference circuit.
* A short to ground or an open/high resistance is detected in the steering angle sensor 5 V reference circuit.
Action Taken When the DTC Sets
* The Stability indicator turns ON.
* The antilock brake system remains functional.
* The driver information center displays the Service Stability System message.
* The EBCM disables the vehicle stability enhancement system for the duration of the ignition cycle.
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 40 consecutive drive cycles.
Reference Information
Schematic Reference
Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
Description and Operation
ABS Description and Operation (Without JL4) Description and OperationABS Description and Operation (With JL4) Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify the scan tool Steering Wheel Position parameter corresponds to the actual steering wheel position as the steering wheel is turned through its entire range of motion.
• If the parameter does not correspond with the steering wheel position or the reading is erratic
Refer to Circuit/System Testing.
• If the parameter corresponds with the steering wheel position
3. Verify the scan tool Digital HWPS Index Pulse parameter cycles between Low and High as the steering wheel is centered and then turned through its entire range of motion.
• If the parameter does not cycle between Low and High as the steering wheel is turned
Refer to Circuit/System Testing.
• If the parameter cycles between Low and High as the steering wheel is turned
4. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the steering angle sensor. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 20 ohms between the low reference circuit terminal 2 and ground.
• If 20 ohms or greater
1. Ignition Off, disconnect the harness connector at the EBCM.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the EBCM.
• If less than 20 ohms
3. Ignition ON.
4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the EBCM.
2. Test for infinite resistance between the 5 V reference circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test to less than 2 ohms in the 5 V reference circuit end to end.
• If 2 ohms for greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the EBCM.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the EBCM, ignition ON.
2. Test for less than 1 V between the 5 V reference circuit terminal 1 and ground
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the EBCM.
• If between 4.8-5.2 V
5. Test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and the signal circuit terminal 6.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the EBCM.
2. Test for less than 2 ohms in the signal circuit end to end.
• If greater than 2 ohms, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the EBCM.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the EBCM, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If greater than 1 V, repair the short to voltage on the circuit.
• If less than 1 V, replace the EBCM.
• If between 4.8-5.2 V
6. Test or replace the steering angle sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Steering Wheel Position Sensor Replacement Steering Wheel Position Sensor Replacement
* Control Module References Control Module References for EBCM replacement, programming and setup