Normal Operation and Fault Conditions
The vacuum pump is mechanically driven by the camshaft. The ABS module uses a sensor mounted on the brake booster to monitor the vacuum. A vacuum pump failure or a leak in the vacuum hoses, check valve, seals, brake booster or front hublock IWE can all cause insufficient vacuum for brake booster operation.
PPT CB ABS MODULE DTC FAULT TRIGGER CONDITIONS
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| P050F:00 | Brake Assist Vacuum Too Low: No Sub Type Information | This DTC sets if the either of these conditions exist. Condition 1: vacuum level in the brake booster is less than -10 kPa (-3 inch Hg) for more than 10 seconds and there are no ABS hydraulic pressure DTCs present and it has been more than 1 minute after engine start or vehicle speed is greater than 1.25 km/h (0.77 mph) for 10 seconds. Condition 2: vacuum level in the brake booster is less than -10 kPa (-3 inch Hg) for more than 1 second and there are ABS hydraulic pressure DTCs present and vehicle speed is greater than 1.25 km/h (0.77 mph) for 10 seconds. |
Possible Causes
- Vacuum hoses
- Front hublock IWE vacuum hose connection
- Brake master cylinder seal
- Vacuum tube grommet
- Vacuum sensor grommet
- CB1: CHECK FOR OTHER ABS MODULE DTCS
- Ignition ON, engine OFF.
- Carry out the ABS self-test.
- Carry out the PCM KOEO self-test.
- Is DTC C101A:15, C101A:16, C101A:1C or C101A:29 present?
Yes No Go to PINPOINT TEST CA . Go to CB2.
- CB2: CHECK THE BRAKE BOOSTER AND VACUUM COMPONENTS
- Ignition OFF.
- Inspect the following components for signs of obvious damage:
- Vacuum tube grommet
- Vacuum sensor grommet
- Brake master cylinder seal
- Vacuum hoses and tubes
- Brake booster
- Front hublock IWE vacuum hose connection
- Are the components listed free from any damage?
Yes No Go to CB3. INSTALL new components as necessary. Go to CB3.
- CB3: TEST THE BRAKE BOOSTER
- Carry out the Component Test - Brake Booster.
- Refer to Diagnosis and Testing in Brake System - General Information (Except Hybrid) .
- Was the component test successful?
Yes No Go to CB4. INSTALL new components as directed by the component test.
- Carry out the Component Test - Brake Booster.
- CB4: VERIFY ABS MODULE VACUUM/PRESSURE SENSOR SIGNAL 1 (VAC_PRS_S1) PID NOTE: Running the engine with the vacuum sensor removed from the brake booster sets DTCs in the ABS module. Clear all DTCs once the repair is complete.
- Start the engine and allow to idle for at least 20 seconds.
- Access the ABS and monitor the VAC_PRS_S1 (PRESS) PID.
- Note the PID display.
- Ignition OFF.
- Remove the vacuum sensor from the brake booster.
- Leave the electrical connector connected.
- Connect a vacuum gauge to the vacuum sensor port.
- Start the engine and allow to idle for at least 20 seconds.
- Read and record the vacuum gauge display.
- Ignition OFF.
- Disconnect the vacuum gauge from the brake booster and install the vacuum sensor.
- Does the VAC_PRS_S1 PID display match the recorded vacuum gauge display ±10 kPa (3 inches Hg)?
Yes No The condition causing the concern is not present at this time. The concern may be temperature related. ALLOW the vehicle to remain outside overnight and RETEST the vacuum system. INSTALL a new Brake Booster Vacuum Sensor. REFER to Power Brake Actuation - Brake Booster (Except Hybrid) .