Active Vacuum Booster

The power brake booster assist unit creates mechanical force for the brake booster in case of a vacuum loss or low vacuum to the brake booster. The power brake booster system consists of:
• The sensor circuits and pressure sensor
• The check valve manifold
• The vacuum solenoid valve

The Power Brake Booster is solenoid operated, and applies a mechanical force to brake master cylinder push rod to aid in brake pedal effort.

The Brake Booster Vacuum Sensor is a input to EBCM, and operates the ABS pump motor to precharge the brake system.

#PIT4046G: Service Brakes Soon Message DTC C0299 - (Oct 21, 2011)

Some customers may experience a "Service Brakes Soon" message on the Drivers Information Center (DIC). After initial inspection, you may find a current or history code C0299. Diagnostic code C0299 can result from two issues. The first may be an electrical concern with the Active Brake Booster solenoid or related wiring. The second may be low vacuum detected in the brake booster.
Recommendation/Instructions:
1. This step is for the 2007 model year only.

Note: For the 2007 model year there are no symptom codes for DTC C0299. Use the below info and take note when the DTC occurs to help determine what is the cause of the DTC:
- If the DTC C0299 sets immediately after cycling the key, an electrical concern with the Active Brake Booster solenoid or the related wiring may be the cause. Diagnose the concern using normal diagnostics in SI.
- If the DTC C0299 sets occasionally while driving or when using the cruise control feature, the concern may be related to a vacuum leak. Diagnose the concern using normal diagnostics in SI. DTC C0299 diagnostics should lead to the Brake Assist System Diagnosis process to investigate for a possible vacuum leak. Follow the Brake Assist System Diagnosis process to determine if a vacuum leak is present and what the appropriate repair is to fully restore the Brake Assist System. Some reports from the field have shown one source of a vacuum leak is the o-ring seal between the brake master cylinder and brake booster; refer to bulletin 08-06-04-016 for more information.

2. This step is for the 2008 model year only.

Note: Starting with the 2008 model year there are symptom codes for DTC C0299.
- DTC C0299 00 may be an electrical concern with the Active Brake Booster solenoid or the related wiring. Diagnose the concern using normal diagnostics in SI.
- DTC C0299 5A may be related to a vacuum leak. Diagnose the concern using normal diagnostics in SI. DTC C0299 diagnostics should lead to the Brake Assist System Diagnosis process. New Tech 2 vacuum sensor data information is available for this concern (Tech 2 Software version 28.001 or greater). Follow the Brake Assist System Diagnosis process to determine if a vacuum leak is present and what the appropriate repair is to fully restore the Brake Assist System. Some reports from the field have shown one source of a vacuum leak is the o-ring seal between the brake master cylinder and brake booster; refer to bulletin 08-06-04-016 for more information.

3. This step is for the 2009 and later models only.

Note: Starting with the 2009 model year there is no longer an Active Brake Booster Solenoid and DTC C0299 will only set one symptom 5A.
- DTC C0299 5A may be related to a vacuum leak. Diagnose the concern using normal diagnostics in SI. DTC C0299 diagnostics should lead to the Brake Assist System Diagnosis process. New Tech 2 vacuum sensor data information is available for this concern (Tech 2 Software version 28.001 or greater). Follow the Brake Assist System Diagnosis process to determine if a vacuum leak is present and what the appropriate repair is to fully restore the Brake Assist System. Some reports from the field have shown one source of a vacuum leak is the o-ring seal between the brake master cylinder and brake booster; refer to bulletin 08-06-04-016 for more information.