SEAL 9V1814 - Caterpillar

Illustration 1 g03388022
Engine start circuit
The components of the engine start circuit are the:
Key start switch
Power Train Electronic Control Module (ECM)
Engine ECM
Start relay magnetic switch
Main relay magnetic switch
Electric starting motor solenoid
Electric starting motor
Transmission control
Fire suppression control loop receptacle (foam type)
Fire suppression control loop plug (dry powder type)
Illustration 2 g03392311
Dash panel
(1) Key start switch
(2) OFF position
(3) ON position
(4) START position
Illustration 3 g01145175
Cab
(5) Power Train ECM
Illustration 4 g01153785
Left side view of engine
(6) Engine ECM With the battery disconnect switch in the ON position, 24 V power is supplied from the batteries via circuit breaker 11 to Engine ECM (6). With key start switch (1) in ON position (3), 24 V power is supplied via:
Circuit breaker 5 to Engine ECM (6)
Circuit breaker 9 to Power Train ECM (5)
Illustration 5 g01429045
Left side view of engine
(7) Start relay magnetic switch
Illustration 6 g01048287
Side view of cab
(8) Main relay magnetic switch
Illustration 7 g01048288
Left side view of engine
(9) Electric starting motor solenoid
(10) Electric starting motor
Illustration 8 g03392313
Cab
(11) Transmission control
(12) Transmission direction control switch When key start switch (1) is in START position (4), Power Train ECM (5) supplies 24 V power to start relay magnetic switch (7). Power then returns to Power Train ECM (5) to ground. Power Train ECM (5) will energize main relay magnetic switch (8) when transmission direction control switch (12) is in the NEUTRAL position. When start relay magnetic switch (8) is energized, 24 V power is supplied to electric starting motor solenoid (9) and to electric starting motor (10). Electric starting motor (10) will begin to crank.Reference: For information on the engine start switch in the OFF position, refer to Systems Operation, Testing, and Adjusting, "Engine Stop" in this manual.