Automotive Electrical and Electronic Systems Classroom Manual Fifth Edition Update by John F. Kershaw

242 Chapter Eleven
Figure 11-25.
cylinder.
Typical coil over plug ignition system on a V-8 with a separate coil/spark plug assembly for each
Figure 11-27. Many oil-filled coils are marked with
the polarity of the primary leads.
Figure 11-26. The laminated iron core within the coil
strengthens the coil’s magnetic field.
tance by reducing current and increasing voltage.
This section of the waveform trace indicates secondary
efficiency. When the secondary voltage
falls below the inductive air-gap voltage level, the
spark can no longer be maintained. The spark gap
becomes nonconductive. The remaining secondary
voltage oscillates in the secondary circuit, dissipating
as heat. This is called secondary voltage deshown
are similar to the secondary circuit traces
seen on an oscilloscope screen. High secondary resistance
causes the spark voltage to increase and a
quick burn time, or short spark duration. This occurs
as the secondary system overcomes the resis-