reset JEEP CHEROKEE 1995 Service User Guide

The powertrain control module (PCM) monitors air
temperature in the intake manifold through the in-
take manifold air temperature sensor. The PCM ad-
justs injector pulse width and ignition timing to
compensate for intake manifold air temperature. Re-
fer to Powertrain Control Module (PCM) for more in-
formation.
For removal and installation procedures of both the
air cleaner housing and the air cleaner element, refer
to the Component Removal/Installation section of
this group
OPEN LOOP/CLOSED LOOP MODES OF
OPERATION
As input signals to the powertrain control module
(PCM) change, the PCM adjusts its response to the
output devices. For example, the PCM must calculate
different injector pulse width and ignition timing for
idle than it does for wide open throttle (WOT). There
are several different modes of operation that deter-
mine how the PCM responds to the various input sig-
nals.
MODES
²Open Loop
²Closed Loop
During Open Loop modes, the powertrain control
module (PCM) receives input signals and respondsonly according to preset PCM programming. Input
from the oxygen (O2S) sensor is not monitored dur-
ing Open Loop modes.
During Closed Loop modes, the PCM will monitor
the oxygen (O2S) sensor input. This input indicates
to the PCM whether or not the calculated injector
pulse width results in the ideal air-fuel ratio. This
ratio is 14.7 parts air-to-1 part fuel. By monitoring
the exhaust oxygen content through the O2S sensor,
the PCM can fine tune the injector pulse width. This
is done to achieve optimum fuel economy combined
with low emission engine performance.
The fuel injection system has the following modes
of operation:
²Ignition switch ON
²Engine start-up (crank)
²Engine warm-up
²Idle
²Cruise
²Acceleration
²Deceleration
²Wide open throttle (WOT)
²Ignition switch OFF
The ignition switch On, engine start-up (crank), en-
gine warm-up, acceleration, deceleration and wide
open throttle modes are Open Loop modes. The idle
and cruise modes, (with the engine at operating tem-
perature) are Closed Loop modes.IGNITION SWITCH (KEY-ON) MODE
This is an Open Loop mode. When the fuel system
is activated by the ignition switch, the following ac-
tions occur:
Fig. 27 Air CleanerÐXJ ModelsÐTypical
Fig. 28 Air CleanerÐYJ ModelsÐTypical
14 - 30 FUEL SYSTEM COMPONENT DESCRIPTION/SYSTEM OPERATIONJ

(6) Position the turn signal switch and wire har-
ness in the cylinder housing. Fold the wires against
the connector. Route the connector down through the
steering column jacket.
(7) Install the windshield wiper wire harness and
switch. Route the wire harness down through steer-
ing column jacket.
(8) Align the turn signal switch in the housing and
secure the switch with the attaching screws. Tighten
the screws to 4 Nzm (35 in. lbs.) torque.
(9) Install the dimmer switch actuator arm.
Tighten the attaching screws to 4 Nzm (35 in. lbs.)
torque.
(10) If equipped, install the cruise control wire har-
ness. Install the turn signal stalk by pushing it
straight into the column.
(11) Position the thrust washer, the upper bearing
preload spring and the canceling cam on the steering
shaft (Fig. 18).
(12) Place the turn signal switch in the neutral
(OFF) position and install the hazard warning switch
knob.
(13) Position the lockplate on the steering shaft.
Install a replacement lockplate retaining snap ring
on the sleeve of the Lock Plate Compressor C-4156.
Install the tool on the steering shaft (Fig. 19).
(14) Compress the lockplate with the compressor
tool and position the retaining snap ring in the steer-
ing shaft groove.
(15) Ensure that the retaining snap ring is com-
pletely seated in the groove before removing the tool.
Remove the tool and install the lockplate cover.(16) Install the steering wheel. Refer to the instal-
lation procedure. Tighten the steering wheel retain-
ing nut to 34 Nzm (25 ft. lbs.) torque.
(17) If removed, install the steering column in the
vehicle. Refer to the installation procedure.
(18) If disconnected, connect the battery negative
cable and, if equipped, reset the clock
Fig. 17 Key/Lock Cylinder InstallationFig. 18 Canceling Cam Position
Fig. 19 Lockplate Snap Ring Installation
JSTEERING 19 - 65

(3) Apply parking brakes and turn off air condi-
tioning unit.
(4) Shift transfer case into 2H range.
(5) Start engine and check curb idle speed. Adjust
speed if necessary. Curb idle must be correct to en-
sure accurate test results.
(6) Shift transmission into Neutral and set stop
watch.
(7) During following test steps, start stop watch as
soon as shift lever reaches D and Reverse ranges.
(8) Shift transmission into D range and record
time it takes for engagement. Repeat test two more
times.
(9) Reset stop watch and shift transmission back to
Neutral.
(10) Shift transmission into Reverse and record
time it takes for engagement. Repeat test two more
times.(11) Engagement time in D range should be a max-
imum of 1.2 seconds. Engagement time for Reverse
should be a maximum of 1.5 seconds.
TIME LAG TEST ANALYSIS
If engagement time is longer than specified for D
range, check for the following:
²shift cable misadjusted
²line pressure low
²forward clutch worn
²overdrive clutch worn or damaged
If engagement time is longer than specified for Re-
verse, check for the following:
²shift cable misadjusted
²line pressure low
²direct clutch worn
²first/reverse brake worn
²overdrive clutch worn or damaged
JAW-4 TRANSMISSION DIAGNOSIS 21 - 179

TRAILER HITCH
TRAILER HITCHÐXJ
CLASS III HITCH
A class III weight-distributing/equalizer type hitch
can be used to tow a trailer:
²Having a maximum gross weight of 5,000 lbs/2250
kg.
²Having a maximum tongue weight of 750 lbs/332
kg).
The following vehicle basic equipment is required
for class III trailer towing:
²P205/75R15 or larger tires.
²Full size spare tire.
²Trailer sway control.
²Trailer tow wire harness and connector.
²Heavy duty turn signal flasher element.
²Heavy duty axle (with synthetic lubricant).
²Heavy duty cooling system.
²Heavy duty generator/battery.
²Auxiliary automatic transmission fluid cooler.
²I-6, 4.0L engine.
Wide-angle type door mirrors are recommended but
not required.
WIRE HARNESS CONNECTORS
CLASS I HITCH CONNECTOR
The trailer tow wire harness connector for class I
trailer hitches is a 5-terminal, in-line type connector.
Terminal 5 is the source for vehicle ground (Fig. 1)
CLASS III HITCH CONNECTOR
The trailer tow wire harness connector for class III
trailer-tow hitches is a 7-terminal, circular type con-
nector (Fig. 2).
The 12-volt circuit for the trailer is protected
from overloads. A auto-reset type circuit
breaker is located in the trailer tow wire har-
ness near the plug-in relays.
CAUTION: The trailer tow wire harness package
does not include a vehicle battery isolator unit. Be-
cause of this, the trailer battery can totally dis-
charge the vehicle battery if the engine is not
operated for an extended period of time.
A blue wire (without a connector) located under in-
strument panel near fuse panel is available for
trailer electric brake control unit.
Fig. 1 Trailer Tow Wire Harness Connectors
JTRAILER HITCH 23 - 77