Jeep Wrangler 1997 Manual page 452

8W - 30 - 2
8W - 30 FUEL/IGNITION SYSTEMS
DESCRIPTION AND OPERATION (Continued)
Circuit Z12 provide ground for the data link con-
nector. Circuit Z12 also connects to cavities A31 and
A32 of the PCM .
AUTOMATIC SHUT DOWN (ASD) RELAY
When the ignition switch is in either the START or
RUN position, it connects circuit Al from fuse 3 in the
Power Distribution Center (PDC) to circuit A21 . Circuit
A21 feeds circuit F12 through fuse 11 in the fuse block .
Circuit F12 powers the coil side of the Automatic Shut
Down (ASD) relay. The Powertrain Control Module
(PCM) provides ground for the relay coil on circuit K51 .
Circuit K51 connects to cavity C3 of the PCM.
When the PCM grounds the ASD relay, contacts
inside the relay close and connect circuit A14 from
fuse 6 in the PDC to circuit A142 . Circuit A142
splices to the fuel injectors, ignition coil and the
upstream and downstream heated oxygen sensors .
Circuit A142 also connects to cavity C12 of the PCM .
HELPFUL INFORMATION
Circuit F12 also powers the coil side of the fuel
pump relay.
FUEL PUMP RELAY
When the ignition switch is in either the START or
RUN positions, it connects circuit Al from fuse 3 in the
Power Distribution Center (PDC) to circuit A21 . Circuit
A21 feeds circuit F12 through fuse 11 in the fuse block.
Circuit F12 powers the coil side of the fuel pump relay.
The Powertrain Control Module (PCM) provides ground
for the relay on circuit K31. Circuit K31 connects to
cavity C19 of the PCM .
When the PCM grounds the fuel pump relay, con-
tacts inside the relay close and connect circuit A61
from fuse 16 in the PDC to circuit A141. Circuit A141
powers the fuel pump motor (part of the in-tank fuel
pump module) .
HELPFUL INFORMATION
Circuit F12 also powers the coils side of the Auto-
matic Shut Down (ASD) relay.
FUEL PUMP MODULE
The in-tank fuel pump module contains the fuel
pump motor and fuel level sensor.
FUEL PUMP MOTOR
When the fuel pump relay contacts close, they con-
nect circuits A61 and A141. Circuit A141 powers the
fuel pump module . Circuit Z1 provides ground for the
fuel pump motor.
FUEL LEVEL SENSOR
The fuel level sensor is a variable resistor. Circuit
K226 provides the fuel level signal to cavity C26 of
the Powertrain Control Module (PCM) . The PCM pro-
TJ
vides ground for the fuel level sensor signal on cir-
cuit K167. Circuit K167 connects to cavity A4 of the
PCM . The PCM broadcasts fuel level data on the
CCD bus . The microprocessor in the instrument clus-
ter monitors the CCD bus to determine the fuel level
and adjusts fuel gauge needle position accordingly.
VEHICLE SPEED SENSOR
Circuit K6 supplies 5 volts from the Powertrain
Control Module (PCM) to the vehicle speed sensor .
The K6 circuit connects to cavity B31 of the PCM .
Circuit G7 from the vehicle speed sensor provides
an input signal to the PCM . The G7 circuit connects
to cavity B27 of the PCM .
The PCM provides a ground for the vehicle speed
sensor signal (circuit G7) through circuit K167. Cir-
cuit K167 connects to cavity A4 of the PCM .
HELPFUL INFORMATION
Circuit K167 splices to supply ground for the sig-
nals from the following :
" Heated oxygen sensors
" Camshaft position sensor
" Crankshaft position sensor
" Throttle position sensor
" Manifold absolute pressure sensor
" Engine coolant temperature sensor
" Intake air temperature sensor
" Battery temperature sensor
" Oil pressure sensor
If the vehicle is equipped with Daytime Running
Lamps (DRL), circuit G7 splices to the DRL module.
HEATED OXYGEN SENSORS
When the Automatic Shut Down (ASD) relay con-
tacts close, they connect circuits A14 and A142. Cir-
cuit A142 splices to supply voltage to the upstream
and downstream heated oxygen sensors .
Circuit K41 delivers the signal from the upstream
heated oxygen sensor to the Powertrain Control Mod-
ule (PCM). Circuit K41 connects to cavity A24 of the
PCM . Circuit K141 supplies the signal from the
downstream heated oxygen sensor to the PCM . Cir-
cuit K141 connects to PCM cavity A25 .
The PCM provides a ground for the heated oxygen
sensor signals (circuits K41 and K141) through cir-
cuit K167. Circuit K167 connects to cavity A4 of the
PCM connector.
Circuit Z1 provides ground for the heater circuit in
each sensor.
HELPFUL INFORMATION
Circuit A142 also supplies battery voltage to the
fuel injectors and ignition coil.
Circuit K167 splices to supply ground for the sig-
nals from the following :
9
Battery temperature sensor