TM 10-3930-669-20 7-17.  MASTER CYLINDER PRESSURE SWITCH REPLACEMENT. This task covers: a.  Removal b.  Installation INITIAL SETUP Tools and Special Tools Tool Kit, General Mechanic's: Automotive (Item 1, Appendix B) Materials/Parts Engine OFF (TM 10-3930-669-10) Parking brake applied (TM 10-3930-669-10) Equipment Condition - Continued Wheels chocked (TM 10-3930-669-10) Cab door opened (TM 10-3930-669-10) Engine access panel opened (TM 10-3930-669-10) Batteries disconnected (Para 7-48) a.  Removal (1) Disconnect connector P21 (1) from brake switch connector (2). (2) Remove pressure switch (3) from fitting (4). 7-37