TM 9-2320-273-20
5-8. STARTING SYSTEM CIRCUIT.
a. Description (fig. 5- 79). The starting system consists of two sets of 12-volt batteries
(connected in series/parallel to provide 24 volts for starting), a starter motor and solenoid, a starter
relay, a neutral safety switch, a key switch (ENGINE RUN), and a start button. When the ENGINE
RUN switch is turned ON, the fuel solenoid valve is opened and power is applied to one side of the
ENGINE START switch. When the transmission ratio selector is in neutral (N) (closing the neutral
safety switch), the starter relay is energized and 24 volts dc is applied to the starter solenoid coil.
Starter solenoid contacts then close and apply 24 volts to the starter motor. When the engine starts,
an overrunning clutch in the starter motor allows the motor to run free until the ENGINE RUN
switch is released, thus removing 24-volt power from the starter motor.
b. Troubleshooting the Starting System Circuits. When you suspect a starting system circuit
problem, perform the steps in table 5-2.
Figure 5-19. Starting System Circuit (Simplified Schematic)
5-22
