Component Tests - Brake System

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COMPONENT TESTS - BRAKE SYSTEM - HYBRID

Accumulator Booster

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. See - Brake System.
1. Apply the parking brake and start the engine.

2. Allow the engine to run for at least 5 minutes.

3. Apply the brake pedal twice, allow the engine to run for an additional 5 minutes and then stop the engine.

4. Apply the brake pedal to check for power assist.


NOTE: There should be enough pressure in the accumulator for at least 2 power-assisted brake applications. If there is enough pressure for at least 2 power-assisted brake applications, the accumulator is functioning correctly.If there is not enough pressure for at least 2 power-assisted brake applications, install a new HCU. See - Hydraulic Control Unit (HCU) - Hybrid Removal/Installation.