O2 SENSOR
DESCRIPTION
The upstream oxygen sensor threads into the out-
let flange of the exhaust manifold (Fig. 22) or (Fig.
23).
The downstream heated oxygen sensor threads into
the outlet pipe at the rear of the catalytic convertor
(Fig. 24).
OPERATION
A seperate upstream and downstream grounds are
used on the NGC vehicles (4 Cyl.).
As vehicles accumulate mileage, the catalytic con-
vertor deteriorates. The deterioration results in aless efficient catalyst. To monitor catalytic convertor
deterioration, the fuel injection system uses two
heated oxygen sensors. One sensor upstream of the
catalytic convertor, one downstream of the convertor.
The PCM compares the reading from the sensors to
calculate the catalytic convertor oxygen storage
capacity and converter efficiency. Also, the PCM uses
the upstream heated oxygen sensor input when
adjusting injector pulse width.
When the catalytic converter efficiency drops below
emission standards, the PCM stores a diagnostic
trouble code and illuminates the malfunction indica-
tor lamp (MIL).
The O2 sensors produce a constant 2.5 volts on
NGC vehicles, depending upon the oxygen content of
the exhaust gas. When a large amount of oxygen is
present (caused by a lean air/fuel mixture, can be
caused by misfire and exhaust leaks), the sensors
produces a low voltage. When there is a lesser
amount of oxygen present (caused by a rich air/fuel
mixture, can be caused by internal engine problems)
it produces a higher voltage. By monitoring the oxy-
gen content and converting it to electrical voltage,
the sensors act as a rich-lean switch.
The oxygen sensors are equipped with a heating
element that keeps the sensors at proper operating
temperature during all operating modes. Maintaining
correct sensor temperature at all times allows the
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 O2
sensors input (along with other inputs) and adjusts
the injector pulse width accordingly. During Open
Loop operation the PCM ignores the O2 sensor input.
Fig. 22 O2 SENSOR UPSTREAM 1/1 - 2.4L
Fig. 23 O2 SENSOR UPSTREAM 1/1 - 3.3/3.8L
Fig. 24 O2 SENSOR DOWNSTREAM 1/2 - 2.4/3.3/
3.8L
14 - 32 FUEL INJECTIONRS
REMOVAL - DOWNSTREAM 1/2 - 2.4/3.3/3.8L
(1) Disconnect the negative battery cable.
(2) Raise and support the vehicle.
(3) Disconnect the electrical connector (Fig. 26).
(4) Use a socket such as the Snap-OntYA8875 or
equivalent to remove the sensor (Fig. 27).
(5) When the sensor is removed, the threads must
be cleaned with an 18 mm X 1.5 + 6E tap. If using
the original sensor, coat the threads with Loctite
771±64 anti-seize compound or equivalent.
INSTALLATION
INSTALLATION - UPSTREAM 1/1 - 2.4L
The engines uses two heated oxygen sensors.
(1) After removing the sensor, the exhaust mani-
fold threads must be cleaned with an 18 mm X 1.5 +
6E tap. If reusing the original sensor, coat the sensor
threads with an anti-seize compound such as Loctite
771- 64 or equivalent. New sensors have compound
on the threads and do not require an additional coat-
ing.
(2) Install sensor and tighten to 27 N´m (20 ft.
lbs.) (Fig. 23).
(3) Connect the electrical connector for the O2 sen-
sor and install onto bracket.
(4) Lower vehicle.
(5) Connect the negative battery cable.
INSTALLATION - UPSTREAM 1/1 - 3.3/3.8L
The engines uses two heated oxygen sensors.
(1) After removing the sensor, the exhaust mani-
fold threads must be cleaned with an 18 mm X 1.5 +
6E tap. If reusing the original sensor, coat the sensor
threads with an anti-seize compound such as Loctite
771- 64 or equivalent. New sensors have compound
on the threads and do not require an additional coat-
ing.
(2) Install sensor and tighten to 27 N´m (20 ft.
lbs.).
(3) Connect the electrical connector for the O2 sen-
sor and install onto bracket.
(4) Connect the electrical connector for the speed
control servo.
(5) Install the speed control servo and bracket
refer to the Speed Control Servo for more informa-
tion.
(6) Connect the speed control vacuum harness to
servo.
(7) Install the battery tray, refer to the Battery
section for more information.
(8) Install battery, refer to the Battery section for
more information.
INSTALLATION DOWNSTREAM 2/1 -
2.4/3.3/3.8L
The O2S is located on the side of the catalytic con-
verter.
Threads of new oxygen sensors are factory coated
with anti-seize compound to aid in removal.DO
NOT add any additional anti-seize compound to
the threads of a new oxygen sensor.
(1) Install sensor and tighten to 27 N´m (20 ft.
lbs.).
(2) Connect the electrical connector.
(3) Lower vehicle.
(4) Install the negative battery cable.
Fig. 26 Downstream Oxygen Sensor (1/2)
1 - OXYGEN SENSOR CONNECTOR
2 - CATALYTIC CONVERTER
3 - DOWNSTREAM OXYGEN SENSOR
4 - ENGINE HARNESS CONNECTOR
Fig. 27 DOWNSTREAM 2/1 O2 SENSOR
14 - 34 FUEL INJECTIONRS
O2 SENSOR (Continued)
THROTTLE BODY
DESCRIPTION
The throttle body is located on the intake manifold
(Fig. 28) or (Fig. 29). Fuel does not enter the intake
manifold through the throttle body. Fuel is sprayed
into the manifold by the fuel injectors.
OPERATION
Filtered air from the air cleaner enters the intake
manifold through the throttle body. The throttle bodycontains an air control passage controlled by an Idle
Air Control (IAC) motor. The air control passage is
used to supply air for idle conditions. A throttle valve
(plate) is used to supply air for above idle conditions.
Certain sensors are attached to the throttle body.
The accelerator pedal cable, speed control cable are
connected to the throttle body cam.
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the PCM.
REMOVAL
(1) Disconnect negative cable from battery cable.
(2) Remove air inlet to throttle body hose clamp.
(3) Remove throttle and the speed control (if
equipped) cables from lever and bracket.
(4) Disconnect electrical connectors from the idle
air control motor and throttle position sensor (TPS)
(Fig. 28) or (Fig. 29).
(5) Remove throttle body to intake manifold
attaching bolts.
(6) Remove throttle body and gasket.
INSTALLATION
(1) Install a new gasket, if required.
(2) Install throttle body.
(3) Tighten throttle body mounting bolts. The 2.4L
to 28.2 N´m (250 50 in. lbs.) torque, The 3.3/3.8L to
11.6 N´m (105 20 in. lbs.) torque.
(4) Connect electrical connectors to the idle air
control motor and throttle position sensor (TPS) (Fig.
28) or (Fig. 29).
(5) Install air inlet to throttle body hose clamp and
tighten.
(6) Connect negative cable to battery cable.
THROTTLE CONTROL CABLE
REMOVAL
(1) Working from the engine compartment, hold
the throttle body throttle lever in the wide open posi-
tion.
(2) Remove the throttle cable from the throttle
body cam.
(3) From inside the vehicle, hold up the pedal and
remove the cable retainer and throttle cable from the
upper end of the pedal shaft.
(4) Remove retainer clip from throttle cable and
grommet at dash panel.
(5) From the engine compartment, pull the throttle
cable and gromment out of the dash panel.
(6) Remove the throttle cable from throttle bracket
by carefully compressing both retaining ears simulta-
Fig. 28 IAC VALVE 2.4L
1 - Idle Air Control Valve
2 - Throttle Position Sensor
Fig. 29 IAC VALVE LOCATION 3.3/3.8L
1 - Idle Air Control Valve
2 - Throttle Position Sensor
RSFUEL INJECTION14-35
neously then gently pull the throttle cable from
throttle bracket or if it is the slide snap design you
have to slide the locking tab out of the hole and then
slide the cable assembly out of the bracket.
INSTALLATION
(1) From the engine compartment, push the hous-
ing end fitting and grommet into the dash panel.In-
stall gromment into the dash panel.
(2) Install the cable housing (throttle body end)
into the cable mounting bracket on the engine.
(3) From inside the vehicle, hold up the pedal and
install throttle cable and cable retainer in the upper
end of the pedal shaft.
(4) At the dash panel, install the cable retainer
clip between the end of the throttle cable fitting and
grommet
(5) From the engine compartment, rotate the
throttle lever wide open and install the throttle
cable.
THROTTLE POSITION SENSOR
DESCRIPTION
The throttle position sensor mounts to the side of
the throttle body (Fig. 30) or (Fig. 31).The sensor
connects to the throttle blade shaft. The TPS is a
variable resistor that provides the Powertrain Con-
trol Module (PCM) with an input signal (voltage).
OPERATION
The signal represents throttle blade position. As
the position of the throttle blade changes, the resis-
tance of the TPS changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
powertrain control module) represents throttle blade
position. The TPS output voltage to the PCM varies
from approximately 0.6 volt at minimum throttle
opening (idle) to a maximum of 4.5 volts at wide open
throttle.
Along with inputs from other sensors, the PCM
uses the TPS input to determine current engine oper-
ating conditions. The PCM also adjusts fuel injector
pulse width and ignition timing based on these
inputs.
REMOVAL - 3.3/3.8L
(1) Disconnect the negative battery cable.
(2) Remove the electrical connector from the Inlet
Air Temperature sensor.
(3) Remove the air cleaner box lid. Remove hose
from throttle body.
(4) Disconnect the electrical connector at TPS.
(5) Disconnect the electrical connector at IAC.
(6) Remove the throttle and speed control cables
from throttle body.
(7) Remove 3 mounting bolts from throttle body.
(8) Remove throttle body.
(9) Disconnect the purge vacuum line from the
throttle body.
(10) Remove TPS from throttle body.
Fig. 30 Throttle Position SensorÐ2.4L Engine
1 - Idle Air Control Valve
2 - Throttle Position Sensor
Fig. 31 Throttle Position SensorÐ3.3/3.8L Engine
1 - Idle Air Control Valve
2 - Throttle Position Sensor
14 - 36 FUEL INJECTIONRS
THROTTLE CONTROL CABLE (Continued)
STEERING
TABLE OF CONTENTS
page page
STEERING
DESCRIPTION - POWER STEERING SYSTEM . . 1
OPERATION - POWER STEERING SYSTEM . . . 1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - POWER
STEERING SYSTEM FLOW AND
PRESSURE TEST......................1
DIAGNOSIS AND TESTING - STEERING
SYSTEM DIAGNOSIS CHARTS............3SPECIFICATIONS
POWER STEERING FASTENER TORQUE . . . 9
SPECIAL TOOLS
POWER STEERING....................9
COLUMN..............................10
GEAR.................................26
PUMP.................................36
STEERING
DESCRIPTION - POWER STEERING SYSTEM
This vehicle comes with power steering as stan-
dard equipment. The power steering system consists
of these major components:
²POWER STEERING PUMP
²POWER STEERING GEAR
²POWER STEERING FLUID
²POWER STEERING FLUID COOLER
²POWER STEERING FLUID RESERVOIR
²POWER STEERING FLUID SUPPLY HOSE
²POWER STEERING FLUID PRESSURE HOSE
²POWER STEERING FLUID RETURN HOSE
For information on the first two components, refer
to their respective sections within this service man-
ual group. Information on all other components can
be found in POWER STEERING PUMP.
OPERATION - POWER STEERING SYSTEM
Turning of the steering wheel is converted into lin-
ear (side-to-side) travel through the meshing of the
helical pinion teeth with the rack teeth within the
steering gear. The lateral travel pushes and pulls the
tie rods to change the direction of the vehicle's front
wheels.
Power assist steering is provided by a belt driven
rotary type pump. It directs fluid through power
steering fluid hoses to the power steering gear where
it is used to assist the driver's turning effort.
Manual steering control of the vehicle can be main-
tained if power steering assist is lost. However,
under this condition, steering effort is significantly
increased.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - POWER STEERING
SYSTEM FLOW AND PRESSURE TEST
ALL ENGINES
The following procedure is to be used to test the
operation of the power steering system on this vehi-
cle. This test will provide the flow rate of the power
steering pump along with the maximum relief pres-
sure. This test is to be performed to determine if the
power steering pump or power steering gear is not
functioning properly. The following flow and pressure
test is performed using the Power Steering Analyzer
Kit, Special Tool 6815 (Fig. 1), hoses, Special Tools
6905 and 6959, and fittings from adapter kit, Special
Tool 6893.
Fig. 1 Power Steering Analyzer With Hoses Installed
1 - OUTLET
2 - SPECIAL TOOL 6815
3 - INLET
RSSTEERING19-1
Assemble hoses on Power Steering Analyzer, Spe-
cial Tool 6815, as shown. Install Pressure Hose, Spe-
cial Tool 6905 (in 6893 kit), in the inlet fitting on
Power Steering Analyzer. Install Pressure Hose, Spe-
cial Tool 6713 (in 6815 kit) on Pressure Hose, Special
Tool 6905. Install Pressure Hose, Special Tool 6959,
in the outlet fitting on Power Steering Analyzer.
Install the following adapters from Adapter Set,
Special Tool 6893 (Fig. 2), on the analyzer hose ends:
Install Adapter Fitting, Special Tool 6844, on Pres-
sure Hose, Special Tool 6713. Install Adapter Fitting,
Special Tool 6826, on Pressure Hose, Special Tool
6959.
CAUTION: To prevent personal injury, safety gog-
gles should be worn at all times when performing
any test procedures on the power steering pump or
power steering gear.
The following procedure is to be used to test the
operation of the power steering system on the vehi-
cle.
(1) Check belt tension and adjust as necessary.
(2) Disconnect the power steering fluid pressure
hose from the power steering pump (Fig. 3) (Fig. 4).
(3) Connect Adapter Fitting, Special Tool 6844,
attached to pressure hose from inlet (gauge end) of
Power Steering Analyzer to the pressure fitting on
the power steering pump.
(4) Connect vehicle power steering fluid pressure
hose to Adapter Fitting, Special Tool 6826, which
should be already installed in the outlet hose (valve
end) of Power Steering Analyzer.NOTE: During the next few steps, do not steer vehi-
cle as air will be forced into the steering gear.
(5) Completely open valve on Power Steering Ana-
lyzer.
Fig. 2 Power Steering Analyzer Adapters 6893
Fig. 3 Pressure Hose Connection To Power Steering
Pump - 2.4L Engine
1 - POWER STEERING FLUID RETURN HOSE
2 - POWER STEERING PUMP
3 - POWER STEERING FLUID PRESSURE HOSE
Fig. 4 Supply & Pressure Hoses At Pump - 3.3L/3.8L
Engine
1 - PRESSURE HOSE AND FITTING
2 - SUPPLY HOSE AND CLAMP
3 - POWER STEERING PUMP
19 - 2 STEERINGRS
STEERING (Continued)
(6) Start engine and let idle just long enough to
circulate power steering fluid through the analyzer
and hoses. Shut off engine.
(7) Check power steering fluid level and add fluid
as necessary. Start engine again and let idle until the
air is out of the fluid.
(8) Gauge should read below 300 psi (2068 kPa). If
above, inspect the hoses for restrictions and repair as
necessary. The initial pressure should be in the range
of 100-275 psi (689-1896 kPa) depending on fluid
temperature. The flow meter should read above 1.5
GPM.
CAUTION: The following test procedure involves
testing maximum pump pressure output and flow
control valve operation. Do not leave valve closed
for more than four seconds as the pump could be
damaged.
NOTE:
Power steering pump maximum pressure for
2.4L engines is 1,200 ± 1,350 psi (8,274 ± 9,308 kPa).
Power steering pump maximum pressure for all other
engines is 1,400 ± 1,500 psi (9,653 ± 10,342 kPa).
(9) Close analyzer valve fully three times and
record highest pressure indicated each time. All three
readings must be within specifications. If any of the
three power steering pump pressures are above orbelow specifications, replace pump. (Refer to 19 -
STEERING/PUMP - REMOVAL)
CAUTION: Do not force the steering to operate
against the stops for more than 4 seconds at a time
because pump damage can result.
(10) Once the pump has been verified as working
correctly, completely open the valve on the Power
Steering Analyzer. Turn the steering wheel to the
extreme left until the stop in the steering gear is
met. Hold it there for 2±4 seconds, then release it.
Now turn the steering wheel to the right until the
right stop is met. Hold it there for 2±4 seconds, then
release it. Record the stabilized pressure at each
position. Compare the recorded readings to the spec-
ifications. If the output pressures are not within 100
psi (689 kPa) of one another against either stop or
are below specifications, the steering gear is leaking
internally and must be replaced. (Refer to 19 -
STEERING/GEAR - REMOVAL)
DIAGNOSIS AND TESTING - STEERING
SYSTEM DIAGNOSIS CHARTS
NOTE: There are three diagnosis charts following
that cover POWER STEERING NOISE, STEERING
WHEEL FEEL, and POWER STEERING FLUID.
POWER STEERING NOISE
CONDITION POSSIBLE CAUSES CORRECTION
OBJECTIONABLE HISS
OR WHISTLE*1. Damaged or mispositioned
steering column shaft/coupling dash
panel seal.1. Reposition or replace steering column
shaft/coupling dash panel seal.
2. Noisy valve in power steering
gear.2. Replace power steering gear.
3. Mis-routed power steering hose. 3. Check routing of power steering
hoses. Ensure hoses do not come in
unwanted contact with other components
and objects.
RATTLE OR EXCESSIVE
CLUNK**1. Power steering gear loose on front
suspension crossmember.1. Inspect power steering gear mounting
bolts. Replace as necessary. Tighten to
the specified torque.
2. Front suspension crossmember
mounting fasteners loose at frame.2. Tighten the front suspension
crossmember mounting fasteners to the
specified torque.
3. Loose tie rod (outer or inner). 3. Check tie rod pivot points for wear.
Replace worn/loose parts as required.
4. Loose lower control arm mounting
bolts at front suspension
crossmember.4. Tighten control arm mounting bolts to
the specified torques.
RSSTEERING19-3
STEERING (Continued)
CONDITION POSSIBLE CAUSES CORRECTION
STEERING WHEEL, DASH
OR VEHICLE VIBRATES
DURING LOW SPEED OR
STANDSTILL STEERING
MANEUVERS.1. Air in the fluid of the power
steering system.1. Bleed air from system following the
power steering pump initial operation
service procedure.*
2. Tires not properly inflated. 2. Inflate tires to the specified pressure.
3. Excessive engine vibration. 3. Ensure that the engine is tuned properly.
4. Loose tie rod end jam nut. 4. Tighten the inner to outer tie rod jam nut
to the specified torque.
5.Overcharged air conditioning
system.5.Check air conditioning pump head
pressure and correct as necessary.
6. Grounded engine mount. 6. Repair as necessary.
7. Loose outer tie rod. 7. Replace outer tie rod.
STEERING CATCHES,
SURGES OR STICKS IN
CERTAIN POSITIONS OR
IS DIFFICULT TO TURN.
***1. Low power steering fluid level. 1. Fill power steering fluid reservoir to
specified level and check for leaks.
2. Tires not inflated to specified
pressure.2. Inflate tires to the specified pressure.
3. Lack of lubrication in front lower
control arm ball joints.3. Lubricate ball joints if ball joints are not a
lubricated-for-life type ball joint. If ball joint
is a lubricated-for-life ball joint, replace ball
joint.
4. Worn or binding lower control arm
ball joint.4. Replace lower control arm ball joint.
5. Lack of lubrication in steering gear
outer tie rod ends.5. Lubricate tie rod ends if they are not a
lubricated-for-life type. If tie rod end is a
lubricated-for-life type, replace tie rod end.
6. Loose power steering pump drive
belt.6. Tighten the power steering pump drive
belt to specifications or replace automatic
tensioner where applicable. If drive belt is
worn or glazed, replace belt.
7. Faulty power steering pump
(Perform Power Steering Flow and
Pressure Test).7. Replace power steering pump.
8. Faulty power steering gear
(Perform Power Steering Flow and
Pressure Test).8. Replace power steering gear.
9. Excessive friction in steering
column or intermediate shaft/coupler.9. Isolate and correct condition.
10. Excessive friction in power
steering gear.10. Replace power steering gear.
11. Worn or binding seat and bearing
in front strut assembly.11. Replace seat and bearing in front strut
assembly.
19 - 6 STEERINGRS
STEERING (Continued)