Accumulator Booster
WARNING: This page is about a different car, the 2008 Mercury Mariner and 2008 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
Hybrid vehicles do not use a conventional brake booster. Instead, the ABS hydraulic control unit (HCU) is equipped with an accumulator that provides the necessary boost for brake application. Refer to VEHICLE DYNAMIC SYSTEMS article for HCU information.
- Apply the parking brake and start the engine.
- Allow the engine to run for at least 5 minutes.
- Apply the brake pedal twice, allow the engine to run for an additional 5 minutes and then stop the engine.
- Apply the brake pedal to check for power assist.
- If there is enough pressure for at least 2 power-asssisted brake applications, the accumulator is functioning correctly.
- If there is not enough pressure for at least 2 power-asssisted brake applications, install a new HCU. Refer to VEHICLE DYNAMIC SYSTEMS article.
NOTE:
There should be enough pressure in the accumulator for at least 2 power-assisted brake applications.