Service manual

G420F(FE) Service Manual Chapter 4. Engine Electrical System 123
Circuit Diagram
IB (Terminal #3), OC (Terminal #1), GND (Terminal
#2)
Inspection
1. Connect terminal #2 (Ground) of Power TR to
Battery (-).
2. Connect terminal #3(IB) of Power TR to Battery
(+5V). If the resistance between terminal #2 and
terminal #1(OC) is lower than 10 ohms, it is OK.
3. Disconnect terminal #3(IB) of Power TR to Battery
(+5V). If the resistance between terminal #2 and
terminal #1(OC) is infinite, it is OK.
Inspection of Ignition Coil
Description
The operation of the ignition system is essentially
the same as any other ignition system. Each coil has
a low primary resistance (0.4 to 0.6 ohms) and steps
up the primary system voltage from 12 volts to as
much as 40,000 volts to produce a spark for the
spark plug.
The primary difference between COP and other
ignition systems is that each COP coil is mounted
directly atop the spark plug so the voltage goes
directly to the plug electrodes without having to pass
through a distributor or wires. It is a direct
connection that delivers the hottest spark possible.
Resistor plugs are generally used to suppress
electromagnetic interference (EMI).