Figure 4-6. Ignition System Circuit

TM 10-3930-633-12

points. When the breaker points open, the

b. Ignition System. The ignition system

magnetic field built up in the primary windings of

consists of two separate circuits, a primary (low

the coil moves through the coil secondary wind-

voltage) and a secondary (high voltage) circuit

i n g s , producing high voltage current. This

(see figure 4-6). The primary circuit consists of

current is produced each time the breaker points

the battery, ignition switch, primary circuit

open. This high voltage flows through the coil

resistance wire, primary coil windings, breaker

high tension lead to the distributor cap, where the

points and condenser. The secondary circuit

rotor distributes it to one of the spark plug ter-

coil windings,

consists

of the secondary

minals in the distributor cap. From the plug

distributor rotor, distributor cap, high tension

terminal the current flows through the secondary

wires and spark plugs.

wire to the spark plug, where the spark ignites the

c. Ignition System Operation. When the

air-fuel mixture in the combustion chamber. This

breaker points are closed, the primary or low

entire process is repeated during every power

voltage current flows from the battery through

stroke of the engine.

the ignition switch to the primary windings in the

coil, then to ground through the closed breaker

Figure 4-6. Ignition System Circuit

the transmission selector lever in any gear range

d. Starting System. The starting system

except Neutral (N). In addition, the vacuum

includes the starting motor and drive, starter

switch prevents starter engagement whenever the

solenoid, battery, starter relay, ignition switch,

engine is running. A diagram of the system is

neutral start switch, and time delay and vacuum

switches. The neutral start switch is normally

open to prevent energizing the starter relay with