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| Illustration 1 | g01001403 |
Engine start circuit | |
The components of the engine start circuit are the key start switch, the Power Train/Chassis Electronic Control Module (Power Train/Chassis ECM), the start relay, the electric starting motor, the electric starting motor solenoid, the parking brake switch, and the Engine Electronic Control Module (Engine ECM).
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| Illustration 2 | g00997821 |
Dash panel (1) Key start switch | |
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| Illustration 3 | g00997826 |
Front view of cab (front cover plate removed) (2) Power Train/Chassis ECM | |
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| Illustration 4 | g00997827 |
Left side view of engine (3) Engine ECM | |
With the key start switch in the ON position, 24 volt power is supplied from the batteries via circuit breaker #3 and circuit breaker #11 to the Engine ECM. 24 volt power is also supplied from the batteries via circuit breaker #12 to Power Train/Chassis ECM.
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| Illustration 5 | g00997839 |
Top view of engine (4) Start relay | |
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| Illustration 6 | g00997844 |
Left side view of engine (5) Electric starting motor (6) Electric starting motor solenoid | |
The machine will not crank unless the following conditions exist:
- The transmission control is in the NEUTRAL position.
- The parking brake switch is in the ENGAGED position.
When the key start switch is in the START position, 24 volt power is supplied to the Power Train/Chassis ECM connector (J1, pin 40). The Power Train/Chassis ECM supplies 24 volt power to energize start relay (4). Power then returns to the Power Train/Chassis ECM connector (J1, pin 7) to ground. When the start relay is energized, power is supplied to the electric starting motor solenoid via the alternator circuit breaker. The electric starting motor will begin to crank.
Reference: For information on the key start switch in the OFF position, refer to Systems Operation, Testing and Adjusting, "Engine Stop" for the machine that is being serviced.