For 1990-2009 cars only
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC C0870 00: Device Voltage Reference Output 1 CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Brake Pressure Sensor Signal | C0870 00 | -- | C0870 00 | -- |
Brake Fluid Pressure Sensor 5-Volt Reference | C0870 00 | C0870 00 | C0870 00 | -- |
Brake Fluid Pressure Sensor Ground | -- | C0870 00 | -- | -- |
Circuit Description
The brake pressure sensor reference voltage is monitored for an over or under voltage condition.
Conditions for Running the DTC
| • | Ignition 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
| • | 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 illuminated. |
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present. |
| • | The electronic brake control module (EBCM) clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
The EBCM detects a short to B+, short to ground, or an open/high resistance in the pressure sensor supply voltage circuit.
Reference Information
Schematic Reference
Antilock Brake System Schematics
Connector End View Reference
Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the EBCM harness connector at the brake fluid pressure sensor.
- Ignition OFF, with a DMM test for less than 5.0 ohms between the brake fluid pressure sensor low reference circuit terminal 1 and ground.
- Ignition ON, with a DMM test for 4.4-5.6 volts between the brake fluid pressure sensor 5-volt reference circuit terminal 3 and ground.
- With the DMM, verify the brake pressure sensor signal range is less than 4.4 volts.
- Install a 3A fused jumper wire between the brake fluid pressure sensor signal circuit terminal 2 and the brake fluid pressure sensor 5-volt reference circuit terminal 3. With a DMM verify the voltage value is greater than 5.6 volts.
- If all circuits test normal, test or replace the brake fluid pressure sensor.
| ⇒ | If greater than the specified range, with the DMM test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the EBCM. |
| ⇒ | If less than the specified range, with the DMM 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, with the DMM test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the EBCM. |
| ⇒ | If greater than the specified value, test the signal circuit terminal 2 for a short to voltage. If the circuit tests normal, replace the EBCM. |
| ⇒ | If less than the specified value, test the signal circuit terminal 2 for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM. |
Component Testing
- Install a 3A fused jumper wire between the brake fluid pressure sensor 5-volt reference terminal 3 and 5 volts. Install a jumper wire between the low reference terminal 1 and ground.
- Sweep the sensor through the entire range while monitoring the resistance between the signal circuit terminal 2 and the low reference circuit terminal 1. The voltage should vary between 4.4-5.6 volts without any spikes or dropouts.
| ⇒ | If not within the specified range or is erratic, replace the brake fluid pressure sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM or EBCM replacement, setup, and programming |
