Dodge ram truck 3500 1996 Service Manual page 627

B R
8W - 20 CHARGING SYSTEM
8W - 20 -1
8W-20 C H A R G I N G S Y S T E M
D E S C R I P T I O N A N D O P E R A T I O N
CHARGING SYSTEM
The charging system is an integral part of the bat­
tery and starting systems. Because all these systems
work in conjunction, diagnose and test them together.
Circuit AO from the battery connects to a bus bar
in the Power Distribution Center (PDC). Circuit A l l
connects to the PDC bus bar and the output terminal
of the generator. A fuse in the PDC between AO and
A l l circuits protects the charging system. Circuit Z l
provides ground for the generator.
On the diesel engine applications an additional
battery is used. Circuit AO connects between the bat­
tery positive terminals of the batteries.
When the ignition switch is in either the START or
RUN positions, i t connects battery voltage from cir­
cuit A l to the A21 circuit. Circuit A21 powers circuit
F18 through fuse 9 in the fuse block. Circuit F18 con­
nects to the coil side of the Automatic Shut Down
(ASD) relay. Circuit A l originates in the PDC and is
connected to battery voltage. A 40 amp fuse in cavity
3 of the PDC protects the A l circuit.
When the ASD relay energizes, i t connects circuit
A16 from the PDC to circuit A142. Circuit A142
splices to connect to the generator connector supply­
ing battery voltage to the generator field.
The- Powertrain Control Module (PCM) has an
internal voltage regulator that controls generator
output. Circuit K20 connects the generator and PCM,
cavity BIO. The PCM controls the generator field on
the K20 circuit.
When the engine operates and there is current in
the generator field, the generator produces a B+ volt­
age. The generator supplies B+ voltage to the battery
through the A l l and AO circuits.
HELPFUL INFORMATION
• Check the 120 amp fuse located in the PDC
• From the ASD relay, circuit A142 splices to sup­
ply voltage to the fuel injectors, ignition coil, fuel
pump module, and the heated oxygen sensors on gas­
oline powered engines
S C H E M A T I C S A N D D I A G R A M S
WIRING DIAGRAM INDEX
The following index covers all components found in
this section of the wiring diagrams. I f the component
you are looking for is not found here, refer to section
8W-02 for a complete list of all components shown in
the wiring diagrams.