Pinpoint Test L: Vacuum Pressure Sensor Faults: Notes
Refer to Vehicle Dynamic Systems for schematic and connector information.
Normal Operation and Fault Conditions
The brake booster vacuum pressure sensor receives a sensor supply voltage of 5 volts from the ABS module. The sensor is also grounded through the ABS module. The sensor uses the pressure differential between the atmosphere and the brake booster vacuum chamber to produce a return voltage signal to the ABS module between 0.39 volt and 4.38 volts. The ABS module uses other sensor inputs such as wheel speed, brake pedal and stability sensors to determine if the vehicle is stopping and at what rate of deceleration. This information is compared against the vacuum pressure sensor to determine the validity of the sensor signal and the working condition of the sensor itself. An open circuit, a short to ground, a short to voltage or a faulted vacuum sensor cause the ABS module to set a DTC.
There are several small ports on the vacuum sensor, if these ports become blocked with dirt or other contaminants, sensor performance is degraded.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| C0047:1C | Brake Booster Pressure Sensor: Circuit Voltage Out Of Range | This DTC sets in continuous memory if the 5-volt sensor supply voltage falls outside of the operational range (4.75 volts to 5.25 volts). |
| C101A:15 | Vacuum Pressure Sensor: Circuit Short To Battery or Open | This DTC sets in continuous memory in the ABS module if the brake booster vacuum sensor return voltage is outside the expected range, 0.3 volt and 4.38 volts. |
| C101A:16 | Vacuum Pressure Sensor: Circuit Voltage Below Threshold | This DTC sets in continuous memory in the ABS module if the brake booster vacuum sensor voltage supply is less than 4.75 volts. |
| C101A:29 | Vacuum Pressure Sensor: Signal Invalid | This DTC sets in continuous memory in the ABS module if the driver applies the brake pedal and the brake fluid pressure sensor indicates an increase in pressure but the vacuum level in the brake booster does not decrease by the expected amount. |
Possible Causes
- Wiring, terminals or connectors
- Low battery voltage
- Brake booster vacuum leak
- Brake booster vacuum sensor
- ABS module
Visual Inspection and Diagnostic Pre-checks
- Inspect the brake booster for vacuum leaks.
- Inspect the brake booster for any obvious signs of damage.
- Inspect the vacuum sensor for any obvious signs of damage, contamination and blockage.
- Make sure the vacuum sensor harness and connector is connected and free of any obvious signs of damage.