Q: How to Determine Which ABS System Is on My Dodge Magnum and How to Remove and Install a Power Brake Booster?
A: Vehicle models equipped with an Anti-lock brake system (ABS) will have one of two different factory systems installed: one is MK25 (the earlier ABS system) and can be Identified by a pressure sensor mounted to the bottom of the master cylinder. The other is MK25E (the later ABS system) and the master cylinder appears typical and is not equipped with a pressure sensor on the bottom. Use this Information to determine which system is on your vehicle. Knowing which system you have is important regarding part identification and torque specifications. The operating check involves depressing the brake pedal several times with the engine off and making sure there's no change in the pedal reserve distance. Then, depress the pedal and start the engine to check if the pedal goes down slightly, indicating normal operation. The airtightness check includes starting the engine and turning it off after one or two minutes, then depressing the brake pedal slowly several times to check if the pedal depresses less each time, indicating an airtight booster. Another airtightness check involves depressing the brake pedal while the engine is running and stopping the engine with the pedal depressed, checking if there's no change in the pedal reserve travel after holding the pedal for 30 seconds. The power brake booster is not serviceable and should be replaced with a new or rebuilt unit. Models equipped with ESP may have additional components integrated with the power brake booster, requiring all original components to be present in the new or rebuilt unit. To remove the power brake booster, start by pressing the brake pedal several times to remove any stored vacuum in the booster. Then, move the driver's seat to the rearmost position and disconnect the cable(s) from the negative battery terminal(s). Remove the windshield wiper motor and the Brake Master Cylinder. Remove any electrical connectors attached to the power brake booster, if applicable. Carefully disconnect the vacuum hose from the brake booster check valve. Inside the vehicle, remove the Brake Light Switch. Pry the retaining clip off of the brake pedal pin and disconnect the booster push rod. Remove the booster mounting fasteners and slide the booster straight out from the firewall until the studs clear the holes. Installation procedures are basically the reverse of removal, including replacing the seal between the power booster and the firewall, tightening the booster mounting nuts, installing a new retaining clip securing the booster pushrod to the brake pedal pin, bleeding the brake system, and testing the operation of the brakes before putting the vehicle into normal service.