TM 10-3930-671-10 2-6. EMERGENCY PROCEDURES. If any emergency arises while operating the truck, immediately stop any operation and shut off engine by turning master electrical switch (1) to OFF. 2-7. UNUSUAL ENVIRONMENTIWNEATHER. The  truck  can  operate  in  many  unusual  conditions.    Operator  PMCS  is  designed  to  cover  many  of  these  conditions. However, operation in extreme heat or cold can require additional checks and services.  The following paragraphs cover these conditions. a. Operation In Extreme Heat. CAUTION • Operating  during  periods  of  extreme  heat  [ambient  temperatures  above  100°F  (38°C)]  can cause  the  truck  engine  and  transmission  systems  to  overheat.    Engine  temperatures  above 212°F (100°C) and transmission fluid temperatures above 210°F (99°C) can cause damage to engine  and  transmission  system  components.    Transmission  fluid  temperatures  should  be checked often during periods of extreme heat to prevent damage to engine and transmission system components. • Gaskets  and  seals  are  more  likely  to  leak  when  engine  and  transmission  system  operating temperatures are high.  Engine and transmission fluid levels should be checked more  often during periods of extreme heat to prevent damage to engine and transmission components. Checks for leaks around gaskets, seals, and fittings should also be made more often. (1) Check engine oil level (para 3-6) and operating temperature often for system temperature above 180°F (82°C).  If engine operating temperature reaches 212°F (100°C), turn engine off. (2)    Check transaxle fluid level (para 3-11) and operating temperature for system temperature above 210°F  (99°C).  If transmission operating temperature is above 210°F (99°C), shut off engine. (3) Perform operator PMCS more often than normal (Table 3-1). 2-11