Diagnostic Instructions

DTC Descriptors

DTC C1101: Base Brake System Pressure Sensor Circuit Performance

DTC 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	C1101
Brake Fluid Pressure Sensor Signal	C1102	C1102	C1102	C1103	C1101
Low Reference	--	C1102	C1102	--	--

Circuit/System Description

The brake pressure sensor measures the line pressure down stream from the master cylinder. The ECM monitors the brake pressure to determine when to command the EBCM to apply and release the front brakes for the hill hold function.

Conditions for Running the DTC

C1101

After the vehicle speed is above 40 km/h (25 mph) and stopped 6 times.

C1102 or C1103

Ignition ON.

Conditions for Setting the DTC

C1101

The EBCM detects the brake pressure sensor reading is stuck indicating the brakes are applied.

C1102

The ECM detects a short to ground or open with the sensor signal circuit or the brake pressure sensor.

C1103

The ECM detects an open with the sensor ground or a short to voltage in either the signal circuit or the brake pressure sensor.

Action Taken When the DTC Sets

DTC C1101-C1103 are Type B DTCs.

Conditions for Clearing the DTC

DTC C1101-C1103 are Type B DTCs.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Hill Hold Control Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the brake master cylinder pressure sensor.
2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal 1 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.

⇒	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.

4. Verify the scan tool ECM Brake Fluid Pressure Sensor 2 parameter is less than 0.15 volt.

⇒	If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM.

5. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 2. Verify the scan tool ECM Brake Fluid Pressure Sensor 2 parameter is greater than 4.75 volts.

⇒	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.

6. If all circuits test normal, test or replace the brake master cylinder pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.