How are ABS Hydraulic Pump issues diagnosed?
Most vehicles with anti-lock brakes will offer an indication of what is happening when the ABS system has stopped functioning properly. When this is the case, the technician will begin by reading trouble codes, and may notice a code referring to low brake fluid pressure. When this is realized, the ABS pump motor and brake fluid pressure sensor are tested. In most vehicles, a jumper wire can be used to send power to the ABS hydraulic pump motor, even when the vehicle is off. If the motor fails to run when provided with power and ground, the motor is diagnosed as defective.
How are ABS Hydraulic Pumps replaced?
Some vehicles have an all inclusive ABS unit which includes the ABS modulator assembly, ABS hydraulic pump, and ABS electronic control module. On these vehicles, the entire ABS unit may need to be replaced by disconnecting the ABS unit electrically and hydraulically from the vehicle, of course, after the negative battery terminal is disconnected. Other vehicles, especially earlier models, allow for replacement of the ABS hydraulic pump motor by disconnecting the pump motor electronically, removing fasteners, and simply pulling the electric motor from the ABS unit.
RepairPal Recommendations for ABS Hydraulic Pump issues
Flush and refill the entire brake system when replacing major components. Any debris or contamination from these components may remain in the system and cause repeat failures. Also, the amount of air entering the brake system and ABS system dictates that the system is thoroughly bled to ensure the service brakes remain operational.
What to look out for when dealing with ABS Hydraulic Pump issues
Removal of the ABS pump motor of ABS hydraulic unit are two very different operations, and understanding which procedure is necessary to fix a faulty ABS hydraulic pump is mandatory. Using a service manual is the only sure way to determine which procedure the vehicle requires, and guessing may result in additional work, or additional cost.