Accumulator and Pump Motor Operations
WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The accumulator is charged independently of the brakes being applied, meaning that the motor may run at any time when the vehicle is powered. The pressure transducer (HPA Pressure) is used by the EBCM to determine when the accumulator pressure is low. The EBCM controls the motor such that it runs from the time when the HPA pressure is seen to be low until the accumulator is fully charged. A dual pump arrangement is used and is driven by an electronically commutator motor.