GMC 25865166 Cylinder Assembly, Brake Master

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To remove the master cylinder, start by removing as much fluid as possible from the reservoir using a syringe or turkey baster. Place rags under the fluid fittings and prepare caps or plastic bags to cover the ends of the lines once they are disconnected. Loosen the fittings at the ends of the brake lines and plug the ends to prevent contamination. Disconnect the electrical connector at the brake fluid level switch, if equipped, and remove the nuts attaching the master cylinder to the power booster. Carefully pull the master cylinder off the studs and out of the engine compartment.

If replacing the reservoir or O-ring, remove as much fluid as possible, detach the reservoir from the master cylinder, replace the O-rings if necessary, lubricate the new O-rings, and secure the reservoir back onto the master cylinder.

Disconnect the cable from the negative battery terminal and unplug the electrical connector for the fluid level warning switch. Remove as much fluid as possible from the reservoir and prepare caps or plastic bags to cover the ends of the lines once they're disconnected.

Disconnect the cable from the negative battery terminal and unplug the electrical connector for the fluid level warning switch. Remove as much fluid as possible from the reservoir and prepare caps or plastic bags to cover the ends of the lines once they're disconnected.