TM 9-2320-303-10 Table 2-1.  Preventive Maintenance Checks and Services (PMCS) for M915A4 (Con't). Location Item To Check/ Not Fully Mission Item No. Interval Service Procedure Capable If: 40 After Radiator WARNING DO  NOT  remove  radiator  cap  unless  engine  is cold.    Remove  cap  in  two  steps.    First,  place thick cloth over cap and slowly turn cap left to first stop.  Pause and allow pressure to escape. Turn  cap  further  left  until  it  can  be  removed. This   is   a   pressurized   cooling   system   and escaping steam, hot water or coolant will cause serious burns. Remove  radiator  cap  (52) and check coolant level in radiator    (53).        Coolant must   be   within   2   1/2   in. (6.4 cm) below filler neck. Add   coolant   as   required (Appendix F). 41 After Horns NOTE Vehicle  operation  with  inoperative  horn  may violate AR 385-55. If tactical situation permits,   check   operation of electrical and air horns. 42 After Acces- sory Items Verify that windshield wipers and heater/ventilator or air conditioner operate. 43 After Lights NOTE Vehicle operation with damaged or inoperative headlights or stoplights may violate AR 385-55. 2-49