
system to enter into closed loop operation sooner.
Also, it allows the system to remain in closed loop
operation during periods of extended idle.
In Closed Loop operation the PCM monitors the
O2S input (along with other inputs) and adjusts the
injector pulse width accordingly. During Open Loop
operation the PCM ignores the O2 sensor input. The
PCM adjusts injector pulse width based on prepro-
grammed (fixed) values and inputs from other sen-
sors.
The Automatic Shutdown (ASD) relay supplies bat-
tery voltage to both the upstream and downstream
heated oxygen sensors. The oxygen sensors are
equipped with a heating element. The heating ele-
ments reduce the time required for the sensors to
reach operating temperature.
UPSTREAM HEATED OXYGEN SENSOR
The upstream O2S is located in the exhaust mani-
fold and provides an input voltage to the PCM. The
input tells the PCM the oxygen content of the
exhaust gas (Fig. 16) or (Fig. 17) or (Fig. 18). The
PCM uses this information to fine tune the air/fuel
ratio by adjusting injector pulse width.
DOWNSTREAM HEATED OXYGEN SENSOR
The downstream heated oxygen sensor threads into
the outlet pipe at the rear of the catalytic convertor
(Fig. 19). The downstream heated oxygen sensor
input is used to detect catalytic convertor deteriora-
tion. As the convertor deteriorates, the input from
the downstream sensor begins to match the upstream
sensor input except for a slight time delay. By com-
paring the downstream heated oxygen sensor input
to the input from the upstream sensor, the PCM cal-
culates catalytic convertor efficiency.When the catalytic converter efficiency drops below
emission standards, the PCM stores a diagnostic
trouble code and illuminates the Malfunction Indica-
tor Lamp (MIL). For more information, refer to
Group 25 - Emission Control Systems.
KNOCK SENSORÐPCM INPUT
The knock sensor is only on the 2.4/3.3/3.8L
engines, not used on the 3.0L engine.
The knock sensor threads into the side of the cyl-
inder block in front of the starter (Fig. 20) or (Fig.
21). When the knock sensor detects a knock in one of
the cylinders, it sends an input signal to the PCM. In
response, the PCM retards ignition timing for all cyl-
inders by a scheduled amount.
Knock sensors contain a piezoelectric material
which sends an input voltage (signal) to the PCM. As
the intensity of the engine knock vibration increases,
the knock sensor output voltage also increases.
Fig. 16 Heated Oxygen SensorÐ2.4L Engine
Fig. 17 Heated Oxygen SensorÐ3.0L Engine
Fig. 18 Heated Oxygen SensorÐ3.3/3.8L Engine
14 - 38 FUEL SYSTEMNS
DESCRIPTION AND OPERATION (Continued)

FUEL LEVEL SENSOR
REMOVAL
Remove fuel reservoir module. Refer to Fuel Reser-
voir Module in this section.
(1) Depress retaining tab and remove the level
sensor connector from theBOTTOMof the fuel mod-
ule electrical connector (Fig. 31).
NOTE: The pump module harness on TOP of flange
is not serviceable or removable.
(2) Pull off blue locking wedge (Fig. 32).
(3) Using a small screwdriver lift locking finger
away from terminal and push terminal out of connec-
tor (Fig. 33).
(4) Push level sensor signal and ground terminals
out of the connector (Fig. 34).(5) Insert a screwdriver between the fuel module
and the top of the level sensor housing (Fig. 35).
Push level sensor down slightly.
(6) Slide level sensor wires through opening fuel
module (Fig. 36).
(7) Slide level sensor out of installation channel in
module.
Fig. 31 Fuel Module/Level Sensor Electrical
Connector
Fig. 32 Wire Terminal Locking Wedge
Fig. 33 Wire Terminal Locking Finger
Fig. 34 Removing Wires From Connector
Fig. 35 Loosening Level Sensor
14 - 18 FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINENS/GS
REMOVAL AND INSTALLATION (Continued)

(4) Raise vehicle on hoist.
(5) Disconnect both the fuel fill and fuel vent rub-
ber hoses at the fuel tank.
(6) Disconnect fuel supply and return lines from
the steel supply line (Fig. 51).
The fuel reservoir module electrical connec-
tor has a retainer that locks it in place.
(7) Slide electrical connector lock to unlock (Fig.
52).
(8) Push down on connector retainer (Fig. 53) and
pull connector off module.
(9) Use a transmission jack to support fuel tank.
Remove bolts from fuel tank straps.
(10) Lower tank slightly. Carefully remove filler
hose from tank.(11) Lower the fuel tank. Remove clamp and
remove fuel filler tube vent hose. Remove fuel tank
from vehicle.
INSTALLATION
(1) Position fuel tank on transmission jack. Con-
nect fuel filler tube vent hose and replace clamp.
(2) Raise tank into position and carefully work
filler tube into tank. A light coating of clean engine
oil on the tube end may be used to aid assembly.
(3) Feed filler vent line thru frame rail. Careful
not to cross lines.
(4) Tighten strap bolts to 54 N´m (40 ft. lbs.)
torque. Remove transmission jack.
CAUTION: Ensure straps are not twisted or bent
before or after tightening strap nuts.
(5) Connect module electrical connector. Place
retainer in locked position.
(6) Lubricate the fuel supply and return lines with
clean 30 weight engine oil, install the quick connect
Fuel Tank
Fig. 51 Fuel Tank and Lines
Fig. 52 Fuel Line Retainers and Pump Connector
Lock
Fig. 53 Module Connector Retainer and Lock
14 - 24 FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINENS/GS
REMOVAL AND INSTALLATION (Continued)

fuel fitting. Refer to Tube/Fitting Assembly in the
Fuel Delivery section of this Group.
(7) Attach filler line to filler tube. Pull on connec-
tor to make sure of connection.
(8) Fill fuel tank, replace cap, and connect battery
negative cable.
FUEL RESERVOIR MODULE
REMOVAL
WARNING: THE FUEL RESERVOIR OF THE FUEL
MODULE DOES NOT EMPTY OUT WHEN THE TANK
IS DRAINED. THE FUEL IN THE RESERVOIR WILL
SPILL OUT WHEN THE MODULE IS REMOVED.
(1) Disconnect negative cable from battery.
(2) Insert fuel siphon hose into fuel filler neck and
push it into the tank.
(3) Drain fuel tank dry into holding tank or a
properly labeleddieselsafety container.
(4) Raise vehicle on hoist.
(5) Use a transmission jack to support the fuel
tank. Remove bolts from fuel tank straps. Lower
tank slightly.
(6) Clean area around fuel reservoir module and
tank to keep dirt and foreign material out of tank.
(7) Disconnect fuel lines from fuel module by
depressing quick connect retainers with thumb and
fore finger (Fig. 54).
(8) Slide module electrical connector lock to
unlock.
(9) Push down on connector retainer (Fig. 55) and
pull connector off module.
(10) Using Special Tool 6856, remove plastic lock-
nut counterclockwise to release pump module (Fig.
56).
(11) Carefully remove module and O-ring from
tank (Fig. 57).(12) Discard old O-ring.
INSTALLATION
(1) Wipe seal area of tank clean and place a new
O-ring seal in position on pump.
(2) Position fuel reservoir module in tank with
locknut.
(3) Tighten locknut to 58 N´m (43 ft. lbs.).
(4) Connect fuel lines.
(5) Plug in electrical connector. Slide connector
lock into position.
(6) Raise fuel tank, install bolts into fuel tank
straps and tighten.
(7) Lower vehicle on hoist.
(8) Connect negative cable from battery.
(9) Fill fuel tank. Check for leaks.
(10) Install fuel filler cap.
Fig. 54 Fuel Line Retainers and Pump Connector
Lock
Fig. 55 Module Connector Retainer and Lock
Fig. 56 Fuel Reservoir Module Lock Nut Removal
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 25
REMOVAL AND INSTALLATION (Continued)

FUEL LEVEL SENSORÐ2.0L ENGINE
Refer to the Fuel Pump Inlet Strainer for the 2.4/
3.0/3.3/3.8L engines under Removal and Installation
in the Fuel Delivery System section of group 14 for
more information.
FUEL TANKÐ2.0L ENGINE
Refer to the Fuel Tank for the 2.4/3.0/3.3/3.8L
engines under Removal and Installation in the Fuel
Delivery System section of group 14 for more infor-
mation.
FUEL INJECTORS
REMOVAL
(1) Disconnect negative cable from battery.
(2) Release fuel system pressure. Refer to Fuel
System Pressure Release procedure in this section.
(3) Disconnect fuel supply tube from rail. Refer to
Quick-Connect Fittings in the Fuel Delivery section
of this group.
(4) Disconnect electrical connectors from fuel injec-
tors (Fig. 4).
(5) Remove fuel rail mounting screws.
(6) Lift rail off of intake manifold. Cover the fuel
injector openings in the intake manifold.
(7) Remove fuel injector retainer (Fig. 5).
(8) Pull injector out of fuel rail. Replace fuel injec-
tor O-rings (Fig. 6).
INSTALLATION
(1) Apply a light coating of clean engine oil to the
upper O-ring.
(2) Install injector in cup on fuel rail.
(3) Install retaining clip.
(4) Apply a light coating of clean engine oil to the
O-ring on the nozzle end of each injector.(5) Insert fuel injector nozzles into openings in
intake manifold. Seat the injectors in place. Tighten
fuel rail mounting screws to 22.5 N´m63 N´m
(200630 in. lbs.).
(6) Attach electrical connectors to fuel injectors.
Fig. 3 Fuel Pressure Test PortÐ2.0LFig. 4 Fuel Rail and Injectors
Fig. 5 Fuel Injector Retainer
Fig. 6 Fuel Injector O-Rings
14 - 30 FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINENS/GS
REMOVAL AND INSTALLATION (Continued)

AIR CONDITIONING (A/C) CONTROLSÐPCM
INPUTS
The A/C control system information applies to fac-
tory installed air conditioning units.
A/C REQUEST SIGNAL:When either the A/C or
Defrost mode has been selected and the A/C low and
high±pressure switches are closed, an input signal is
sent to the powertrain control module (PCM). The
PCM uses this input to cycle the A/C compressor
through the A/C relay.
If the A/C low or high±pressure switch opens, the
PCM will not receive an A/C request signal. The
PCM will then remove the ground from the A/C relay.
This will deactivate the A/C compressor clutch. Also,
if the engine coolant reaches a temperature outside
normal of its normal range, or it overheats, the PCM
will deactivate the A/C clutch.
BRAKE SWITCHÐPCM INPUT
When the brake light switch is activated, the PCM
receives an input indicating that the brakes are
being applied. After receiving this input, the PCM is
used to control the speed control system. There is a
Primary and a Secondary brake switch. The Second-
ary brake switch is closed until the brake pedal is
pressed.
DATA LINK CONNECTORÐPCM INPUT AND
OUTPUT
The 16±way data link connector (diagnostic scan
tool connector) links the Diagnostic Readout Box(DRB) scan tool with the PCM. The data link connec-
tor is located under the instrument panel near the
bottom of steering column (Fig. 7).
VEHICLE SPEED SENSORÐPCM INPUT
The vehicle speed sensor (Fig. 8) is located in the
extension housing of the transmission. The sensor
input is used by the PCM to determine vehicle speed
and distance traveled.
Fig. 6 Speed Sensor Operation
Fig. 7 Data Link Connector Location
Fig. 8 Vehicle Speed SensorÐTypical
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 47
DESCRIPTION AND OPERATION (Continued)

VEHICLE LEADS TO THE SIDE
POWER STEERING FLUID LEAK
CONDITION POSSIBLE CAUSES CORRECTION
STEERING WHEEL DOES NOT
WANT RETURN TO CENTER
POSITION.1. Radial tire lead. 1.Rotate tires as recommended in
the Tire And Wheel Group of this
service manual.
2. Front suspension misaligned. 2. Align the front suspension as
required. Refer to the Wheel
Alignment Procedure in the
Suspension Group of this service
manual for the required wheel
alignment procedure.
3. Wheel braking. 3. Check for dragging brakes. Refer
to the procedures in the Brake
Group of this service manual.
4. Unbalanced steering gear valve.
(If this is the cause, the steering
efforts will be very light in direction
of lead and heavier in the opposite
direction.4. Replace steering gear.
STEERING WHEEL HAS FORE
AND AFT LOOSENESS.1. Steering wheel to steering column
shaft retaining nut not properly
tightened and torqued.1. Tighten the retaining nut to its
specified torque specification.
2. Steering column lower bearing
spring retainer slipped on steering
column shaft.2. Replace steering column.
3. Loose steering column to
instrument panel mounting nuts.3. Verify that the 4 mounting nuts for
the steering column are tightened to
the specified torque.
4. Binding intermediate steering
shaft coupler.4. Disconnect intermediate steering
coupler and see if looseness no
longer exists. If yes replace
intermendiate steering coupler.
CONDITION POSSIBLE CAUSES CORRECTION
LOW FLUID LEVEL WITH: NO
VISIBLE SIGNS OF A LEAK ON
THE STEERING GEAR, POWER
STEERING PUMP, FLOOR OR
ANYWHERE ELSE.1. Overfilled power steering pump
fluid reservoir.1. Adjust the power steering fluid fill
to the correct level.
LOW FLUID LEVEL WITH:
VISIBLE LEAK ON STEERING
GEAR, POWER STEERING
PUMP, FLOOR OR ANYWHERE
ELSE.2. Power steering hose connections
at the power steering pump or
steering gear.2. Check for loose fittings and if
found, tighten the fitting to its
specified torque. If fittings are tight
examine the fittings for damaged or
missing O-ring seals and replace as
required.
3. Power steering pump or power
steering gear leaking.3. Identify the location of the leak
and repair or replace the component
as required. Refer to Power Steering
Pump and/or Power Steering Gear in
this group of the service manual for
required procedures.
NSSTEERING 19 - 7
DIAGNOSIS AND TESTING (Continued)

POWER STEERING PUMP FLOW AND
PRESSURE TEST PROCEDURE
(1) Check power steering pump drive belt tension
and adjust as necessary.
(2) Disconnect power steering fluid pressure hose,
at power steering pump. Use a container for dripping
fluid.
(3) Connect Pressure Gauge, Special Tool from kit
6815 to both hoses using adapter fittings. Connect
spare pressure hose, to power steering pump pres-
sure hose fitting.
(4) Completely open valve on Special Tool 6815.
(5) Start engine and let idle long enough to circu-
late power steering fluid through flow/pressure test
and get air out of fluid. Then shut off engine.
(6) Check power steering fluid level, and add fluid
as necessary. Start engine again and let idle.
(7) Pressure gauge should read below 862 kPa
(125 psi), if above, inspect the hoses for restrictions
and repair as necessary. The initial pressure reading
should be in the range of 345-552 kPa (50-80 psi).
The flow meter should read between 1.3 and 1.9
GPM
CAUTION: The following test procedure involves
testing power steering pump maximum pressure
output and flow control valve operation. Do not
leave valve closed for more than 5 seconds as the
pump could be damaged.
(8) Close valve fully three times and record high-
est pressure indicated each time.All three read-
ings must be within specifications and within
345 kPa (50 psi) of each other.
NOTE: Power steering pump maximum relief pres-
sure is 9653 to 10342 kPa (1400 to 1500 psi.).
²If power steering pump pressures are within the
specifications but not within 345 kPa (50 psi) of each
other, then replace power steering pump.
²If pressures are within 345 kPa (50 psi) of each
other but below specifications, then replace power
steering pump.
CAUTION: Do not force the pump to operate
against the stops for more than 5 seconds at a time
because, pump damage will result.
(9) Open test valve. Turn steering wheel to the
extreme left and right positions until against the
stops, recording the highest indicated pressure at
each position. Compare pressure gauge readings to
power steering pump specifications. If highest output
pressures are not the same against either stop, the
steering gear is leaking internally and must be
replaced.
SERVICE PROCEDURES
POWER STEERING SYSTEM FLUID LEVEL CHECK
WARNING: FLUID LEVEL SHOULD BE CHECKED
WITH ENGINE OFF TO PREVENT INJURY FROM
MOVING PARTS. DO NOT USE AUTOMATIC TRANS-
MISSION FLUID IN THE POWER STEERING SYS-
TEM. DO NOT OVERFILL THE POWER STEERING
SYSTEM.
Wipe reservoir filler cap free of dirt. Then check
fluid level. The dipstick should indicate COLD when
fluid is at normal ambient temperature, approxi-
mately 21ÉC to 27ÉC (70ÉF to 80ÉF). In all pumps add
fluid as necessary, use onlyMopar Power Steering
Fluid, or equivalent. DO NOT USE ANY TYPE
OF AUTOMATIC TRANSMISSION FLUID.
POWER STEERING PUMP INITIAL OPERATION
CAUTION: The fluid level should be checked with
engine off to prevent injury from moving compo-
nents. Use only MoparTPower Steering Fluid. Do
not use automatic transmission fluid. Do not over-
fill.
Wipe filler cap clean, then check the fluid level.
The dipstick should indicateFULL COLDwhen the
fluid is at normal temperature of approximately 21ÉC
to 27ÉC (70ÉF to 80ÉF).
(1) Fill the pump fluid reservoir to the proper level
and let the fluid settle for at least two (2) minutes.
(2) Start the engine and let run for a few seconds.
Then turn the engine off.
(3) Add fluid if necessary. Repeat the above proce-
dure until the fluid level remains constant after run-
ning the engine.
(4) Raise the front wheels off the ground.
(5) Start the engine. Slowly turn the steering
wheel right and left, lightly contacting the wheel
stops.
(6) Add power steering fluid if necessary.
(7) Lower the vehicle and turn the steering wheel
slowly from lock to lock.
(8) Stop the engine. Check the fluid level and refill
as required.
(9) If the fluid is extremely foamy, allow the vehi-
cle to stand a few minutes and repeat the above pro-
cedure.
19 - 10 STEERINGNS
DIAGNOSIS AND TESTING (Continued)