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: Brake Booster Vacuum Sensor Performance

### Diagnostic Fault Information

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

### Circuit/System Description

The electronic brake control module (EBCM) provides a power 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 voltage signal. This signal is sent to the EBCM. The voltage signal ranges, from 0.13-3.30 volts depending on vacuum levels. The low reference is the return side of the sensor to ground.

### Conditions for Running the DTC

• | The ignition is ON.

• | Ignition voltage is greater than 9 volts.

### Conditions for Setting the DTC

• | Voltage at the brake booster sensor signal output to the EBCM falls outside the 0.13-3.30 volts range for more than 200 milliseconds.

• | The power 5-volt reference is shorted to ground or battery positive.

### Action Taken When the DTC Sets

The red BRAKE Warning indicator illuminates.

### 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 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. Test for less than 1.0 ohm of resistance between the low reference circuit terminal and ground.

⇒ | If greater than 1.0 ohm, 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 and ground.

⇒ | If less than 4.8 volts, 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 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the EBCM.

4. Test for 4.5-5.3 volts between the 5-volt reference circuit terminal and the signal circuit terminal.

⇒ | 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 specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the EBCM.

5. Install a 3 A fused jumper wire at the signal circuit terminal . Toggle the jumper wire between the low reference circuit terminal and the 5-volt reference circuit terminal. Verify the scan tool Brake Pressure Sensor Input parameter toggles between 0.2-3.2 volts.

⇒ | If the specified parameter, does not toggle between the minimum and maximum values test the signal circuit for a short to voltage, short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.

6. 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