1994 JEEP CHEROKEE power steering

OVERDRIVE/OVERRIDE SWITCH
On vehicles equipped with overdrive, the power-
train control module (PCM) regulates the 3-4 over-
drive up-shift and down-shift through the overdrive
solenoid.
Refer to Group 21 for more information.
OXYGEN (O2S) SENSORÐPCM INPUT
The O2S sensor is located in the exhaust down pipe
(Fig. 11). It provides an input voltage to the power-
train control module (PCM) relating the oxygen con-
tent of the exhaust gas. The PCM uses this
information to fine tune the air-fuel ratio by adjust-
ing injector pulse width.
The O2S sensor produces voltages from 0 to 1 volt.
This voltage will depend upon the oxygen content of
the exhaust gas in the exhaust manifold. When a
large amount of oxygen is present (caused by a lean
air-fuel mixture), the sensor produces a low voltage.
When there is a lesser amount present (rich air-fuel
mixture) it produces a higher voltage. By monitoring
the oxygen content and converting it to electrical
voltage, the sensor acts as a rich-lean switch.
The oxygen sensor is equipped with a heating ele-
ment that keeps the sensor at proper operating tem-
perature during all operating modes. Maintaining
correct sensor temperature at all times allows the
system to enter into closed loop operation sooner.
In Closed Loop operation, the powertrain control
module (PCM) monitors the O2S sensor input (along
with other inputs). It then adjusts the injector pulse
width accordingly. During Open Loop operation, the
PCM ignores the O2S sensor input and adjusts injec-
tor pulse width to a preprogrammed value (based on
other sensor inputs).
PARK/NEUTRAL SWITCHÐPCM INPUT
The park/neutral switch is located on the transmis-
sion housing and provides an input to the powertrain
control module (PCM). This will indicate that the au-
tomatic transmission is in Park, Neutral or a drivegear selection. This input is used to determine idle
speed (varying with gear selection), fuel injector
pulse width and ignition timing advance. Refer to
Group 21, Transmissions, for testing, replacement
and adjustment information.
POWER GROUND
The power ground is used to control ground circuits
for the following powertrain control module (PCM)
loads:
²Generator Field Winding
²8 volt (PCM) power supply
²Fuel Injectors
²Ignition Coil
POWER STEERING PRESSURE SWITCHÐPCM
INPUT
A pressure sensing switch is included in the power
steering system (mounted on the high-pressure line).
This switch will be on vehicles equipped with a 2.5L
engine and power steering. The switch (Fig. 12 YJ
Models or Fig. 13 XJ Models) provides an input to
the PCM. This input is provided during periods of
high pump load and low engine rpm; such as during
parking maneuvers. The PCM will then increase the
idle speed through the idle air control (IAC) motor.
This is done to prevent the engine from stalling un-
der the increased load.
When steering pump pressure exceeds 1896 kPa6
172 kPa (275625 psi) the PCM will increase the en-
gine idle speed. This will prevent the engine from
stalling.
SCI RECEIVEÐPCM INPUT
SCI Receive is the serial data communication re-
ceive circuit for the DRB scan tool. The powertrain
control module (PCM) receives data from the DRB
through the SCI Receive circuit.
Fig. 11 Heated Oxygen Sensor LocationÐTypical
Fig. 12 Power Steering Pump Pressure SwitchÐYJ
Models
14 - 22 FUEL SYSTEMJ

SPEED CONTROLÐPCM INPUT
The speed control system provides three separate
inputs to the powertrain control module (PCM); On/
Off, Set and Resume. The On/Off input informs the
PCM that the speed control system has been acti-
vated. The Set input informs the PCM that a fixed
vehicle speed has been selected. The Resume input
indicates to the PCM that the previous fixed speed is
requested.
The speed control operating range is from 50 km/h
to 142 km/h (35 to 85 mph). Inputs that effect speed
control operation are:
²Park/neutral switch
²Vehicle speed sensor
²Throttle position sensor
Refer to Group 8H for further speed control infor-
mation.
SENSOR RETURNÐPCM INPUT
Sensor Return provides a low noise ground refer-
ence for all system sensors.
THROTTLE POSITION SENSOR (TPS)ÐPCM INPUT
The Throttle Position Sensor (TPS) is mounted on
the throttle body (Figs. 14 or 15). The TPS is a vari-
able resistor that provides the powertrain control
module (PCM) with an input signal (voltage) that
represents throttle blade position. The sensor is con-
nected to the throttle blade shaft. As the position of
the throttle blade changes, the resistance of the TPS
changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
PCM) represents the throttle blade position. The
PCM receives an input signal voltage from the TPS.
This will vary in an approximate range of from 1
volt at minimum throttle opening (idle), to 4 volts at
wide open throttle. Along with inputs from other sen-
sors, the PCM uses the TPS input to determine cur-rent engine operating conditions. In response to
engine operating conditions, the PCM will adjust fuel
injector pulse width and ignition timing.
VEHICLE SPEED SENSORÐPCM INPUT
The vehicle speed sensor (Fig. 16) is located in the
extension housing of the transmission (2 wheel drive)
or on the transfer case extension housing (4 wheel
drive). The sensor input is used by the powertrain
control module (PCM) to determine vehicle speed and
distance traveled.
The speed sensor generates 8 pulses per sensor rev-
olution. These signals, in conjunction with a closed
throttle signal from the throttle position sensor, indi-
cate a closed throttle deceleration to the PCM. When
the vehicle is stopped at idle, a closed throttle signal
is received by the PCM (but a speed sensor signal is
not received).
Under deceleration conditions, the PCM adjusts the
idle air control (IAC) motor to maintain a desired
MAP value. Under idle conditions, the PCM adjusts
the IAC motor to maintain a desired engine speed.
Fig. 13 Power Steering Pump Pressure SwitchÐXJ
Models
Fig. 14 Throttle Position SensorÐ2.5L Engine
Fig. 15 Throttle Position SensorÐ4.0L Engine
JFUEL SYSTEM 14 - 23

MULTI-PORT FUEL INJECTION (MFI)ÐCOMPONENT REMOVAL/INSTALLATION
INDEX
page page
Accelerator Pedal and Throttle Cable......... 54
Air Cleaner Housing...................... 54
Air Conditioning (A/C) Clutch Relay........... 54
Air Filter............................... 54
Automatic Shut Down (ASD) Relay........... 54
Brake Switch............................ 54
Camshaft Position Sensor.................. 54
Crankshaft Position Sensor................. 55
Engine Coolant Temperature Sensor.......... 55
Fuel Filter.............................. 55
Fuel Injector............................ 55
Fuel Pump Module....................... 56
Fuel Pump Relay........................ 56
Fuel Rail Assembly....................... 56
Fuel System Pressure Release Procedure...... 56
Fuel Tank Pressure Relief/Rollover Valve...... 56
Fuel Tanks............................. 56Fuel Tubes/Lines/Hoses and Clamps.......... 56
Idle Air Control (IAC) Motor................. 56
Ignition Coil............................. 57
Intake Air Temperature Sensor.............. 54
Intake Manifold.......................... 57
Manifold Absolute Pressure (MAP) Sensor..... 57
Oxygen (O2S) Sensor..................... 57
Park Neutral Switch....................... 58
Power Steering Pressure SwitchÐ2.5L
Engine Only........................... 58
Powertrain Control Module (PCM)............ 58
Quick-Connect Fittings..................... 59
Throttle Body............................ 59
Throttle Position Sensor (TPS).............. 59
Torque Converter Clutch Relay.............. 60
Vehicle Speed Sensor..................... 60
ACCELERATOR PEDAL AND THROTTLE CABLE
Refer to the Accelerator Pedal and Throttle Cable
section of this group for removal/installation proce-
dures.
AIR CONDITIONING (A/C) CLUTCH RELAY
The A/C clutch relay is located in the Power Dis-
tribution Center (PDC) (Figs. 1 or 2). For location of
this relay within the PDC, refer to label on PDC
cover.
AIR CLEANER HOUSING
Refer to Group 25, Emission Control System.
AIR FILTER
Refer to Group 25, Emission Control System.
AUTOMATIC SHUT DOWN (ASD) RELAY
The ASD relay is located in the Power Distribution
Center (Figs. 1 or 2) (PDC). For location of this relay
within the PDC, refer to label on PDC cover.
BRAKE SWITCH
Refer to Group 5, Brakes for removal/installation
procedures.
CAMSHAFT POSITION SENSOR
For removal/installation procedures, refer to Group
8D, Ignition System. See Camshaft Position Sensor.
INTAKE AIR TEMPERATURE SENSOR
The intake manifold air temperature sensor is in-
stalled into the intake manifold plenum (Figs. 3 or
4).
Fig. 1 PDCÐYJ Models
Fig. 2 PDCÐXJ Models
14 - 54 FUEL SYSTEMJ

(3) Lower the vehicle.
PARK NEUTRAL SWITCH
Refer to Group 21, Transmissions for park neutral
switch service.
POWER STEERING PRESSURE SWITCHÐ2.5L
ENGINE ONLY
The power steering pressure switch is installed in
the power steering high pressure hose (Figs. 11 or
12).
REMOVAL
(1) Disconnect the electrical connector from the
power steering pressure switch.
(2) Place a small container or shop towel beneath
the switch to collect any excess fluid.
(3) Remove the switch.
INSTALLATION
(1) Install the power steering switch.
(2) Connect the electrical connector to the switch.(3) Check power steering fluid and add as neces-
sary.
(4) Start the engine and again check power steer-
ing fluid. Add fluid if necessary.
POWERTRAIN CONTROL MODULE (PCM)
On XJ models, the PCM is located in the engine
compartment next to the air cleaner (Fig. 13). On YJ
models, the PCM is located in the engine compart-
ment behind the windshield washer fluid reservoir
(Fig. 14).
REMOVAL
(1) Disconnect the negative battery cable at the
battery.
(2) YJ Models Only: Remove the windshield
washer fluid tank.
(3) Loosen the 60-Way connector mounting bolt
(Figs. 13 or 14).
(4) Remove the electrical connector by pulling
straight back.
(5) Remove the three PCM mounting bolts.
(6) Remove PCM.
Fig. 11 Power Steering Pressure SwitchÐYJ Models
Fig. 12 Power Steering Pressure SwitchÐXJ Models
Fig. 13 PCM LocationÐXJ Models
Fig. 14 PCM LocationÐYJ Models
14 - 58 FUEL SYSTEMJ

STEERING
CONTENTS
page page
GENERAL INFORMATION.................. 1
MANUAL STEERING GEAR............... 35
NON-TILT STEERING COLUMN............ 50
POWER STEERING PUMP................. 9
POWER STEERING SYSTEM DIAGNOSIS..... 3
RECIRCULATING BALL POWER STEERING GEAR.19STEERING COLUMN GENERAL SERVICE.... 45
STEERING LINKAGEÐXJ................. 14
STEERING LINKAGEÐYJ................. 17
STEERING RHD........................ 69
TILT STEERING COLUMN................ 59
TORQUE SPECIFICATIONS................ 73
GENERAL INFORMATION
STEERING SYSTEM COMPONENTS
Jeep vehicles can have either a manual or power
steering system (Fig. 1). A recirculating-ball type
steering gear is used for both systems.
Power steering systems use;
²Steering gear
²Pressure and return fluid hoses and fittings
²Belt driven steering pump
²Integral or remote body mounted pump reservoir
POWER STEERING GEAR
The steering gear is mounted on the left frame rail.
The gear is joined to the intermediate shaft by a uni-
versal joint coupling. The coupling helps isolate noise
and road shock from the interior.
The major internal components of the gear are the:
²Rotary valve assembly
²Steering worm shaft
²Rack piston assembly
²Pitman shaft
The movement of these parts, while turning or
parking, is aided by hydraulic pressure and flow sup-plied by the pump. Manual steering is always avail-
able at times when the engine is not running or in
the event of pump or belt failure. Steering effort is
higher under such conditions.
The steering stub shaft, rotary valve, worm shaft,
and rack piston assembly are all in line. The oil pas-
sages are internal within the gear housing except for
pressure and return hoses between the gear and
pump.
The power steering gear has a recirculating ball
system. This acts as a rolling thread between the
worm shaft and rack piston. The worm shaft is sup-
ported by a thrust bearing at the lower end and a
bearing assembly at the upper end. When the worm
shaft is turned right, the rack piston moves up in
gear. Turning the worm shaft left moves the rack
piston down in gear. The rack piston teeth mesh with
the sector, which is part of the pitman shaft. Turning
the worm shaft turns the pitman shaft, which turns
the wheels through the steering linkage.
The control valve in the steering gear directs the
power steering fluid to either side of the rack piston.
The rack piston is assisted by hydraulic pressure. If
the steering system loses hydraulic pressure, the ve-
hicle can be controlled manually, but with higher
steering effort.
An identification code located on the side cover des-
ignates the gear ratio (Fig. 2).
²Code BH designates 14:1 ratio used in XJ vehicles
²Code BF designates 13-16:1 ratio used in YJ vehi-
cles
A recirculating-ball steering gear is used with the
power (assisted) steering system (Fig. 1). The power
steering gear can be adjusted and internally serviced.
POWER STEERING PUMP
Hydraulic pressure is provided for operation of the
power steering gear by a belt driven power steering
Fig. 1 Steering Gears
JSTEERING 19 - 1

pump. The power steering pump is a constant flow
rate and displacement, vane-type pump. The internal
parts in the housing operate submerged in fluid. The
flow control orifice is part of the high pressure line
fitting. The pressure relief valve inside the flow con-
trol valve limits the pump pressure.
Power steering pumps have different pres-
sure rates and are not interchangeable with
other pumps.
The power steering pump is connected to the steer-
ing gear via high pressure and return hose. The
pump shaft has a pressed-on drive pulley that is belt
driven by the crankshaft pulley (Fig. 3).
XJ vehicles with 2.5L engines and all YJ vehicles:
The reservoir is mounted at the front left side of the
engine compartment. XJ vehicles equipped with a
4.0L engine have the reservoir attached to the pump
body with spring clips.
STEERING COLUMNS
Two general types of steering columns are installed
on Jeep vehicles: a fixed, non-tilt column and a tilt
column (Fig. 4).
The ignition key/lock cylinder is located in the
steering column. When the key/lock cylinder is
turned to the LOCK position, the ignition switch and
steering shaft cannot be operated. For vehicles with
an automatic transmission, the lock mechanism also
prevents operation of the gear shift mechanism.The center, slip-type intermediate shaft is attached
to the steering gear and steering column shaft with
universal joints.
Both types of steering columns have anti-theft pro-
visions. They are energy-absorbing.
Fig. 3 TC Series Pump With Integral Reservoir
Fig. 4 Steering Columns
Fig. 2 Ratio Code Location
19 - 2 STEERINGJ

POWER STEERING SYSTEM DIAGNOSIS
PUMP PRESSURE TEST
(1) Check belt tension and adjust as necessary.
(2) Disconnect high pressure hose at gear or pump.
Use a container for dripping fluid.
(3) Connect Gauge 7617 (J21567) to both hoses us-
ing adapter fitting (Fig. 1). Connect spare pressure
hose to gear or pump.
(4) Open the test valve completely.
(5) Start engine and let idle.
(6) Check fluid level, add fluid as necessary.
(7) Gauge should read below 862 kPa (125 psi), if
above, inspect the hoses for restrictions and repair as
necessary. The initial pressure should be in the
range of 345-552 kPa (50-80 psi).CAUTION: The following test procedure involves
testing maximum pump 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 highest
pressure indicated each time.All three readings
must be above specifications and within 345
kPa (50 psi) of each other.
²Pressures above specifications but not within 345
kPa (50 psi) of each other, replace pump.
²Pressures within 345 kPa (50 psi) of each other
but below specifications, replace pump.
CAUTION: Do not force the pump to operate against
the stops for more than 2 to 4 seconds at a time.
Pump damage will result.
(9) Open the test valve, turn steering wheel ex-
treme left and right positions against the stops.
Record the highest indicated pressure at each posi-
tion. Compare readings to specifications. If highest
output pressures are not the same against either
stop, the gear is leaking internally and must be re-
paired.
Fig. 1 Pressure Test Gauge
PUMP OPERATING SPECIFICATIONS
JSTEERING 19 - 3

POWER STEERING SYSTEM DIAGNOSIS
19 - 4 STEERINGJ