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 C1101: Base Brake System Pressure Sensor Circuit PerformanceDTC C1102: Base Brake System Pressure Sensor Circuit Low Voltage
DTC C1103: Base Brake System Pressure Sensor Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
5-Volt Reference | C1102 | C1102 | C1102 | C1103 | -- |
Brake Fluid Pressure Sensor Signal | C1102 | C1102 | C1102 | C1103 | C1101 |
Low Reference | -- | C1102 | C1102 | -- | -- |
Circuit/System Description
The engine control module (ECM) uses the inputs from the brake fluid pressure sensor to monitor and control the hill start assist function. The EBCM receives a serial data message to command the HCU valves closed to maintain the applied brake pressure when the vehicle is stopped. The ECM will command the EBCM to open the valves and release the pressure after the engine restarts.
Conditions for Running the DTC
C1101
| • | Engine is running and vehicle speed is above 25 mph/40 kph. |
| • | DTCs C1102, C1103 or vehicle speed DTCs have not set. |
| • | The transmission is in the drive position. |
C1102 or C1103
| • | Engine is running. |
| • | This diagnostic runs continuously. |
Conditions for Setting the DTC
C1101
| • | Engine is running. |
| • | The condition exists above 25 mph/40 kph. |
C1102 or C1103
| • | The ECM detects a short to ground or open with the brake fluid sensor signal circuit. |
| • | The condition exists for more than 30 seconds. |
Action Taken When the DTC Sets
| • | MIL is illuminated. |
| • | ABS warning indicator is illuminated. |
Conditions for Clearing the DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
Reference Information
Schematic Reference
Connector End View Reference
Antilock Brake System Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the brake fluid pressure sensor.
- Ignition OFF, test for less than 5 ohms between the low reference circuit terminal and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal and ground.
- Verify the scan tool ECM Brake Fluid Pressure Sensor parameter is in the correct range.
- Install a 3A fused jumper wire between the signal circuit terminal and the 5-volt reference circuit terminal. Verify the scan tool Brake Fluid Pressure Sensor parameter is greater than correct range.
- If all circuits test normal, test or replace the brake fluid sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | 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 ECM. |
| ⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit terminal for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup and programming |
