298 SUPPLEMENT FOR 1980 M O D E L
Pick-up Coil Output Voltage
at Low and High Speed
A. Pick-up Coil Assembly
I C Igniter
The I C igniter utilizes the voltage pulse sent from the
pick-up coil as follows t o obtain stable induced high
tension voltage from low t o high engine speeds. The
o u t p u t voltage o f the pick-up coil alternates as shown
i n Fig. N99.
O o t p u t Voltage o f Pick-up Coil
( N 9 9 )
at high spccd
at low speed
Dwell Time and Primary Current
(Breaker Point System)
(when middle speed)
Points open (when high speed)
With rotation o f the timing rotor the output voltage
rises, and the power transistor conducts and permits
primary current to flow when the pick-up coil output
reaches the preset voltage (V on).
When the output
voltage drops to the other preset voltage ( V o f f ) after
passing the voltage peak, the power transistor no longer
conducts stopping the current flow i n the ignition coil
primary winding and inducing a high tension voltage
that jumps across the spark plug electrodes. I n the case
o f a standard breaker point ignition system the dwell
time (the time during which current can flow in the
primary circuit) decreases as the engine speed increases.
This results i n less current flow through the ignition
coil primary winding and decreased induced voltage at
high rpm. Conversely the dwell time i n this transistor-
ized ignition system is kept relatively constant by virtue
o f the pick-up coil output voltage. This is because the
faster the engine runs, the higher the output voltage o f
the pick-up coil becomes and the sooner the V o n volt-
age is reached.
Therefore the dwell angle increases
t o keep the dwell time long enough at high engine rpm
so that the induced high voltage does n o t decrease.
lgnition Coil, Timing Advancer, Spark Plug
Refer t o Pgs. 221
lgnition System Troubleshooting Guide
I f trouble is suspected i n the ignition system, check
the system by the following procedure.
A n example o f troubleshooting is shown in Fig. N102.
T o use this chart, follow the arrows on the chart select-
ing a "yes" or "no" arrow at each diamond-shaped step
until you reach the "end".
Each test procedure is ex-
plained individually on the pages after the chart. This
chart is for one half o f the ignition circuit; use the
same chart for the other half.