Automatic Shut Down (Asd) Relay; Camshaft Position Sensor-3.9L V-6 Or 5.2/5.9L; Engines - Chrysler RAM TRUCK 2500 1994 Service Manual

8D - 2 IGNITION SYSTEMS
•
tical with each engine using a mechanical distributor.
Similarities and differences between the systems will
be discussed.
The ignition system used on the 8.0L V-10 engine
does not use a conventional mechanical distributor. I t
will be referred to as a Direct Ignition System (DIS)
or, distributor-less ignition system.
Basic ignition timing is not adjustable on any
engine.
A sequential multi-port fuel injection system is
used on all 3.9L V-6 or 5.2/5.9L V-8 gas powered en­
gines. On the 8.0L V-10 engine, a multi-port fuel in­
jection system is also used, although the fuel
injectors are operated i n pairs.
The ignition coils on the V-10 are individually fired,
but each coil is a dual output. Refer to Ignition Coil
Packs—8.0L V-10 Engine i n this Ignition System
group for additional information. Also refer to Group
14, Fuel Systems for additional information.
The ignition system is controlled by the powertrain
control module (PCM) on all engines (Fig. 1). The
PCM was formerly referred to as the SBEC or engine
controller.
POWERTRAIN CONTROL
MODULE (PCM) J9414-11
Fig. 1 PCM Location—Typical
An additional ignition control module (ICM) is used
to partially control ignition coil operation on the 8.0L
V-10 engine only. Refer to Ignition Coil Packs—8.0L
V-10 Engine i n this Ignition System group for addi­
tional information.
The ignition system consists of:
• Spark Plugs
• Ignition Coil (multiple coils with the 8.0L V-10 en­
gine)
• Secondary Ignition Cables
• Ignition distributor. Contains rotor and camshaft
position sensor (3.9L V-6 or 5.2/5.9L V-8 engines
only)
• Ignition Control Module (8.0L V-10 engine only)
• Powertrain Control Module (PCM)
• Crankshaft Position Sensor
• Camshaft Position Sensor
AUTOMATIC SHUT DOWN (ASD) RELAY
The ASD relay is located i n the Power Distribution
Center (PDC) near the vehicle battery (Fig. 2). For
the location of this relay within the P D C , refer to
PDC cover.
As one of its functions, the ASD relay will supply
battery voltage to the ignition coil (or coil packs i f
equipped with a V-10 engine). The ground circuit for
the ASD relay is controlled by the powertrain control
module (PCM). The PCM regulates ASD relay opera­
tion by switching the ground circuit to the ASD relay
on-and-off.
Fig. 2 Power Distribution Center (PDC) Location
CAMSHAFT POSITION SENSOR—3.9L V-6 OR
5.2/5.9L V-8 ENGINES
The camshaft position sensor is located i n the igni­
tion distributor (Fig. 3) on all 3.9L V-6 or 5.2/5.9L V-8
engines.
Fig. 3 Camshaft Position Sensor—3.9L V-6 or
5.2/5.9L V-8 Engines—Typical
SENSOR OPERATION- 3.91 V-6 OR
5.Z5.9L
V-8 ENGINES
The camshaft position sensor contains a hall effect