The ignition system consists of the following components:
• | Camshaft position (CMP) sensor, or pick-up coil |
• | Ignition control (IC) module |
The powertrain control module (PCM) provides the ignition timing signal for
the vehicle ignition system. The PCM receives information on engine status from the
engine sensors. The PCM then selects the most appropriate ignition timing settings
from within the PCMs programming. The PCM sends a signal to the IC module. The ignition
control module is connected to the negative side of the ignition coil's primary circuit.
When the signal from the PCM is interrupted, the field around the primary coil collapses
and a high voltage is induced in the secondary coil. The high voltage induced in the
secondary coil is then forced to find a ground through the secondary (coil) wire,
the rotor, the distributor cap, the secondary (spark plug) wires and across the spark
plug gap to the engine block. The following are the most important inputs for determining
ignition timing requirements:
• | The engine coolant temperature |
Noteworthy Ignition Information
Consider the following important information when servicing the ignition system:
• | The ignition coil's secondary output voltage is very high - more
than 40,000 volts. Avoid body contact with the ignition high voltage secondary
components when the engine is running or personal injury may result. |
• | The ignition timing is not adjustable. A timing indicator and timing marks
are visible at the crankshaft pulley but are not used to set or adjust ignition timing.
The powertrain control module provides all ignition timing adjustments electronically. |
• | Be careful not to damage the secondary ignition wires or boots when servicing
the ignition system. Rotate each ignition wire boot in order to loosen the boot from
the spark plug before removing the wire. Never pierce a secondary ignition wire or
boot for any testing purposes. Future ignition system problems are guaranteed if pinpoints
or test lights are pushed through the secondary ignition wire insulation during component
testing. |