This pair of opposed brake fluid pumps is the single most common failure on otherwise serviceable ABS Hydraulic Units rendering them non functional. It is exceedingly common to find one of both of these pumps seized in theirs bores, unable to perform the critical functions.
Any time the 12v DC motor is running these pumps should be operating, and depending on the ABS ECU's control state they will either be responsible for returning brake fluid to the master cylinder during a pressure reduction event ( operator experiences pedal pulsation ) or during a pressure increase event after wheel lockup is concluded ( and the operator is still applying firm pedal pressure )
These two scenarios occur multiple times a second. Without well operating pumps ABS cannot function.
Some vehicle owners may elect to attempt replacement of these components themselves before considering a full rebuild of the unit.
All completely refurbished ABS Hydraulic Units purchased from this store include a R/I Pump Set.
