JEEP YJ 1995 Service And Repair Manual

GROUND DISTRIBUTION
GENERAL INFORMATION
This section identifies the grounds, splices that
connect to those grounds, and the components that
connect those grounds. For additional information on
system operation, refer to the appropriate section of
the wiring diagrams. For an illustration of the phys-
ical location of each ground, refer to group 8W-90.
DIAGRAM INDEX
Component Page
G101................................8W-15-2
G102................................8W-15-2
G103................................8W-15-2
G104................................8W-15-3
G105................................8W-15-3
G106................................8W-15-4
G107................................8W-15-4Component Page
G108................................8W-15-4
S104................................8W-15-2
S106................................8W-15-2
S112................................8W-15-3
S119................................8W-15-3
S122................................8W-15-3
S125................................8W-15-4
J8W-15 GROUND DISTRIBUTIONÐYJ VEHICLES 8W - 15 - 1

CHARGING SYSTEM
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 A11 connects to the generator output termi-
nal and splices to fuse 2 and fuse 6 in the Power Dis-
tribution Center (PDC). Circuit A0 connects the
battery to the PDC.
Circuit Z0 provides ground for the generator. Cir-
cuit Z0 attaches to the right side rear of the engine.
When the ignition switch is in either the START or
RUN position, it connects circuit A1 from fuse 4 in
the PDC to circuit A21. Circuit A21 powers fuse 5 in
the fuse block. Circuit G50 from fuse 5 splices to
power the coil side of the Automatic Shut Down
(ASD) relay. The Powertrain Control Module (PCM)
provides ground for the relay on circuit K51. Circuit
K51 connects to cavity 51 of the PCM.
When the PCM grounds the ASD relay, contacts in-
side the relay close and connect circuit A14 from fuse
1 in the PDC to circuit A142. Circuit A142 splices to
the generator field terminal.
The PCM has an internal voltage regulator that
controls generator output. The PCM controls the gen-
erator field on circuit K20. Circuit K20 connects to
PCM cavity 20.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 A11 and A0 circuits.
HELPFUL INFORMATION
²The ignition switch also connects circuit A1 with
circuits A41, A22, and A31.
²Circuit A21 also powers fuse 9 in the fuse block.
²Circuit G50 also powers the coil sides of the fuel
pump relay and the torque convertor clutch (TCC) re-
lay.
²The ASD relay supplies battery voltage for the fuel
injectors, ignition coil, and the heated oxygen sensor.
²Circuit K51 also provides ground for the coil side
of the fuel pump relay.
DIAGRAM INDEX
Component Page
Battery...............................8W-20-2
Fuse 2 (PDC)...........................8W-20-2
Fuse 6 (PDC)...........................8W-20-2
Generator..............................8W-20-2
Powertrain Control Module (PCM)..............8W-20-2
J8W-20 CHARGING SYSTEMÐYJ VEHICLES 8W - 20 - 1

STARTING SYSTEM
STARTING SYSTEM
AUTOMATIC TRANSMISSIONS
Circuit A0 from the battery is double crimped at
the positive battery post. One branch of circuit A0
(battery positive cable) connects to the engine starter
motor. The other A0 branch supplies voltage to the
bus bar in the Power Distribution Center (PDC).
The PDC supplies battery voltage to the engine
starter motor solenoid on circuit T40 when the coil
side of the engine starter motor relay energizes. Cir-
cuit A1 from the fuse 4 in the PDC supplies battery
voltage to the contact side of the starter motor relay.
The ignition switch supplies battery voltage to the
coil side of the starter motor relay on circuit A41
when the key is moved to the START position and
the Park/Neutral position switch is closed. Ground
for the coil side of the starter motor relay is supplied
by the case grounded Park/Neutral position switch.
Circuit T41 connects the coil side of the relay to the
Park/Neutral position switch.
When the starter motor relay energizes and the
contacts close, circuit T40 supplies battery voltage to
the starter motor solenoid. Circuit A0 from the bat-
tery supplies voltage to the starter motor when the
solenoid energizes.
MANUAL TRANSMISSIONS
Circuit A0 from the battery is double crimped at
the positive battery post. One branch of circuit A0
(battery positive cable) connects to the battery
starter motor. The other A0 branch supplies voltage
to the bus bar in the Power Distribution Center
(PDC).The PDC supplies battery voltage to the engine
starter motor solenoid on circuit T40 when the coil
side of the engine starter motor relay energizes. Cir-
cuit A1 from the fuse 4 in the PDC supplies battery
voltage to the contact side of the starter motor relay.
The ignition switch supplies battery voltage to the
coil side of the starter motor relay on circuit A41
when the key is moved to the START position. Cir-
cuit T41 from the coil side of the relay connects to a
Z2 jumper wire in the back-up lamp switch. Circuit
Z2 provides ground for the starter motor relay.
When the starter motor relay energizes and the
contacts close, circuit T40 supplies battery voltage to
the starter motor solenoid. Circuit A0 from the bat-
tery supplies voltage to the starter motor when the
solenoid energizes.
HELPFUL INFORMATION
²The Park/Neutral switch closes when the trans-
mission is in either the PARK or NEUTRAL posi-
tions.
²Circuit T41 also connects to cavity 30 of the Pow-
ertrain Control Module (PCM). This input tells the
PCM the operator is starting the vehicle.
DIAGRAM INDEX
Component Page
Engine Starter Motor......................8W-21-2
Engine Starter Motor Relay..................8W-21-2
Ignition Switch..........................8W-21-2
Park/Neutral Position Switch.................8W-21-2
Power Distribution Center (PDC)...............8W-21-2
Powertrain Control Module (PCM)..............8W-21-2
Fuse 4 (PDC)...........................8W-21-2
J8W-21 STARTING SYSTEMÐYJ VEHICLES 8W - 21 - 1