RAM 2500 Truck 4WD V10-8.0L VIN W (1997)
Ignition Coil: Description and Operation
Coil Pack
Fig 3 Ignition Coil Packs
DESCRIPTION
The ignition system used on this engine does not use a conventional mechanical distributor. It will be referred to as a distributor-less ignition
system. Ignition timing is not adjustable.
Two separate coil packs containing a total of five independent coils are attached to a common mounting bracket located above the right engine
valve cover. The coil packs are not oil filled. The front coil pack contains three independent epoxy filled coils. The rear coil pack contains two
independent epoxy filled coils.
OPERATION
When one of the 5 independent coils discharges, it fires two paired cylinders at the same time (one cylinder on compression stroke and the other
cylinder on exhaust stroke). The ignition system is controlled by the powertrain control module (PCM) on all engines. The PCM was formerly
referred to as the SBEC or engine controller.
Coil firing is paired together on cylinders:
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Number 5 and 10
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Number 9 and 8
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Number 1 and 6
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Number 7 and 4
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Number 3 and 2
The automatic shutdown (ASD) relay, after receiving signals from the crankshaft and camshaft position sensors, will supply battery voltage to all
of the ignition coil positive terminals. If these signals are not received by the PCM after approximately one second of engine cranking (start-up),
the ASD relay will shut off positive voltage to all of the coils. Coil operation (firing) is then controlled by switching ground circuits (off-and-on)
through the PCM. The PCM will determine cylinder identification after receiving signals from the crankshaft and camshaft position sensors.
The PCM adjusts ignition timing based on inputs it receives from:
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The engine coolant temperature sensor
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The crankshaft position sensor (engine speed)
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The manifold absolute pressure (MAP) sensor
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The throttle position sensor
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Transmission gear selection
