For 1990-2009 cars

### 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 C1100 00: Base Brake System Pressure Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
5-Volt Reference | C1100 00 | C1100 00 | C1100 00 | --
Signal | C1100 00 | C1100 00 | C1100 00 | --
Low Reference | -- | C1100 00 | -- | --

### Circuit/System Description

The electronic brake control module (EBCM) provides a 5-volt reference to the brake booster vacuum sensor. The brake booster vacuum sensor converts the change in vacuum levels in the brake booster into a signal voltage ranging from 0.13-3.30 volts and is monitored by EBCM.

### Conditions for Running the DTC

Ignition ON.

### Conditions for Setting the DTC

The brake booster sensor signal voltage is not within 0.13-3.30 volts for more than 1 second.

### Conditions for Clearing the DTC

• | The condition for the DTC is no longer present.

• | The EBCM clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

### Reference Information

#### Schematic Reference

Antilock Brake System Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

ABS Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the brake booster vacuum sensor.
2. Ignition OFF for 60 seconds, test for less than 11 ohms between the low reference circuit terminal 2 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 EBCM.

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

⇒ | If less than the specified range, test the 5-volt reference circuit for an open/high resistance. If the circuit tests normal, replace the replace the EBCM.

⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to B+. If the circuit tests normal, replace the EBCM.

4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and the signal circuit terminal 1.

⇒ | If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.

⇒ | If greater than the specified range, test the signal circuit for a short to B+. If the circuit tests normal, replace the EBCM.

5. Ignition OFF, disconnect the harness connector at the EBCM.
6. Ignition OFF, test for infinite resistance between the signal circuit terminal 1 and ground.

⇒ | If not the specified value, test the signal circuit for a short to ground.

7. If all circuits test normal, test or replace the brake booster vacuum sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Power Brake Booster Vacuum Sensor Replacement

• | Control Module References for EBCM replacement, setup, and programming