Pinpoint Test Q : C101A:1C, C101A:2A, C101A:2F, C101A:62: Notes
Diagnostic Overview
C101A:1C, C101A:2A, C101A:2F, C101A:62
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 that is between 0.2 volt and 4.9 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.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| C101A:1C | Vacuum Pressure Sensor: Circuit Voltage Out of Range | This DTC sets in continuous memory and on-demand if the signal returning from the vacuum pressure sensor is outside of the normal operating range. This can be due to a short to battery, a short to ground, an open in the signal return circuit, an internal failure of the sensor or an internal failure of the ABS module. Also, when the sensor fails internally, the diagnostics integrated in the sensor drives the output signal to either the maximum (4.9 volts) or minimum (0.2 volt) voltage. An internal failure is set if the output signal is within the upper or lower voltage range longer than the specified minimum fault duration of 100 ms. |
| C101A:2A | Vacuum Pressure Sensor: Signal Stuck In Range | This DTC sets in continuous memory and on-demand if, after 3 brake pedal applications, the signal returning from the vacuum pressure sensor did not have a very significant change or did not change at all. This can be due to a short to battery, a short to ground, an open in one or more of the sensor circuits or a mechanical failure of the brake booster. |
| C101A:2F | Vacuum Pressure Sensor: Signal Erratic | This DTC sets in continuous memory and on-demand if the signal returning from the vacuum pressure sensor both increases and decreases during the same brake pedal application. This is usually cause by an internal failure of the sensor. |
| C101A:62 | Vacuum Pressure Sensor: Signal Compare Failure | This DTC sets in continuous memory and on-demand if the pressure difference between the vacuum chambers in the brake booster is not at least -20 kPa (-3 psi) for more than 2 minutes with the engine running. This is usually caused by an mechanical failure of the brake booster resulting in a vacuum leak. |
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 brake booster vacuum sensor harness and connector of any obvious signs of damage.
- Make sure the brake booster vacuum sensor electrical connector is free from any corrosion or other contaminants.