drive cycle JEEP GRAND CHEROKEE 2003 WJ / 2.G User Guide

tem functions, as well as separate hard wired sense
inputs to the BCM for the high speed continuous
wipe and front washer system functions.
The front wiper and washer system will only oper-
ate when the ignition switch is in the Accessory or
On positions. Battery current is directed from a B(+)
fuse in the Power Distribution Center (PDC) to the
wiper and washer system circuit breaker in the Junc-
tion Block (JB) through a fused ignition switch out-
put (run-acc) circuit. The automatic resetting circuit
breaker then provides battery current through a
fused ignition switch output (run-acc) circuit to the
wiper on/off relay, and the park switch in the front
wiper motor. A separate fuse in the JB provides bat-
tery current through another fused ignition switch
output (run-acc) circuit to the right multi-function
switch. The right multi-function switch circuitry uses
this battery feed to directly control the operation of
the front washer pump/motor unit. The BCM uses
low side drivers to control front wiper system opera-
tion by energizing or de-energizing the wiper high/
low and wiper on/off relays.
The hard wired circuits and components of the
front wiper and washer system may be diagnosed
and tested using conventional diagnostic tools and
procedures. However, conventional diagnostic meth-
ods may not prove conclusive in the diagnosis of the
Body Control Module (BCM), or the inputs to or out-
puts from the BCM that control the front wiper and
washer system operating modes. The most reliable,
efficient, and accurate means to diagnose the BCM,
or the BCM inputs and outputs related to the various
front wiper and washer system operating modes
requires the use of a DRBIIItscan tool. Refer to the
appropriate diagnostic information.
Following are paragraphs that briefly describe the
operation of each of the front wiper and washer sys-
tem operating modes.
CONTINUOUS WIPE MODE
When the Low position of the control knob on the
control stalk of the right (wiper) multi-function
switch is selected, the Body Control Module (BCM)
energizes the wiper on/off relay. This directs battery
current through the normally open contacts of the
energized wiper on/off relay and the normally closed
contacts of the de-energized wiper high/low relay to
the low speed brush of the front wiper motor, causing
the front wipers to cycle at low speed. When the
High position of the control knob is selected, the
BCM energizes both the wiper on/off relay and the
wiper high/low relay. This directs battery current
through the normally open contacts of the energized
wiper on/off relay and the normally open contacts of
the energized wiper high/low relay to the high speedbrush of the front wiper motor, causing the front wip-
ers to cycle at high speed.
When the Off position of the control knob is
selected, the BCM de-energizes both the wiper on/off
and wiper high/low relays, then one of two events
will occur. The event that will occur depends upon
the position of the wiper blades on the windshield at
the moment that the control knob Off position is
selected. If the wiper blades are in the down position
on the windshield when the Off position is selected,
the park switch that is integral to the front wiper
motor is closed to ground and the wiper motor ceases
to operate. If the wiper blades are not in the down
position on the windshield at the moment the Off
position is selected, the park switch is closed to bat-
tery current from the fused ignition switch output
(run-acc) circuit of the front wiper motor. The park
switch directs this battery current to the low speed
brush of the wiper motor through the wiper park
switch sense circuit and the normally closed contacts
of the wiper on/off and wiper high/low relays. This
causes the wiper motor to continue running at low
speed until the wiper blades are in the down position
on the windshield and the park switch is again
closed to ground.
INTERMITTENT WIPE MODE
On models not equipped with the optional auto-
matic wiper system, when the control knob on the
control stalk of the right (wiper) multi-function
switch is moved to one of the five Delay interval posi-
tions, the BCM electronic intermittent wipe logic cir-
cuit responds by calculating the correct length of
time between wiper sweeps based upon the selected
delay interval input. The BCM monitors the chang-
ing state of the wiper motor park switch through a
hard wired front wiper park switch sense circuit
input. This input allows the BCM to determine the
proper intervals at which to energize and de-energize
the wiper on/off relay to operate the front wiper
motor intermittently for one low speed cycle at a
time. The BCM logic is also programmed to provide
an immediate wipe cycle and begin a new delay
interval timing cycle each time a shorter delay inter-
val is selected, and to add the remaining delay tim-
ing interval to the new delay interval timing before
the next wipe cycle occurs each time a longer delay
interval is selected.
The intermittent wipe mode delay times are speed
sensitive. The BCM monitors vehicle speed messages
received from the Powertrain Control Module (PCM)
over the Programmable Communications Interface
(PCI) data bus network in order to provide the speed
sensitive delay intervals. Above about sixteen kilome-
ters-per-hour (ten miles-per-hour) the delay is driver
adjustable from about one-half second to about eigh-
WJFRONT WIPERS/WASHERS 8R - 5
FRONT WIPERS/WASHERS (Continued)

ods may not prove conclusive in the diagnosis of the
Body Control Module (BCM), the Rain Sensor Mod-
ule (RSM), the Powertrain Control Module (PCM) or
the inputs to or outputs from these modules that con-
trol the various front wiper and washer system oper-
ating modes. The most reliable, efficient, and
accurate means to diagnose the BCM, the RSM, the
PCM or the BCM inputs and outputs related to the
various front wiper and washer system operating
modes requires the use of a DRBIIItscan tool. Refer
to the appropriate diagnostic information.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SIDE CURTAIN AIRBAG,
FRONT IMPACT SENSOR, SIDE IMPACT SENSOR,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
FRONT WASHER SYSTEM
The diagnosis found here addresses an electrically
inoperative washer system. If the washer pump/mo-
tor operates, but no washer fluid is emitted from the
front washer nozzles, be certain to check the fluid
level in the reservoir. Also inspect the front washer
system components as required. (Refer to 8 - ELEC-
TRICAL/FRONT WIPERS/WASHERS - INSPEC-
TION). Refer to the appropriate wiring information.
The wiring information includes wiring diagrams,
proper wire and connector repair procedures, details
of wire harness routing and retention, connector pin-
out information and location views for the various
wire harness connectors, splices and grounds.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SIDE CURTAIN AIRBAG,
FRONT IMPACT SENSOR, SIDE IMPACT SENSOR,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
(1) Turn the ignition switch to the On position.
Turn the control knob on the control stalk of the
right (wiper) multi-function switch to the Low or
High wiper position. Check whether the front wiper
system is operating. If OK, go to Step 2. If not OK,
test and repair the front wiper system before con-
tinuing with these tests. Refer to FRONT WIPER
SYSTEM
(2) Turn the control knob on the control stalk of
the right (wiper) multi-function switch to the Off
position. Pull the control stalk of the right (wiper)
multi-function switch toward the steering wheel to
close the front washer switch. The front washer
pump should operate and the front wipers should
operate for about three sweep cycles after the switch
is released before they park. If the front wipers are
OK, but the front washers are not, go to Step 3. If
the front washers are OK, but the front wipers are
not, go to Step 5.
(3) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the left headlamp and dash wire harness
connector for the front washer pump/motor from the
pump/motor connector receptacle. Check for continu-
ity between the ground circuit cavity of the left head-
lamp and dash wire harness connector for the front
washer pump/motor and a good ground. There should
be continuity. If OK, go to Step 4. If not OK, repair
the open ground circuit to ground (G106) as required.
(4) Reconnect the battery negative cable. Turn the
ignition switch to the On position. While pulling the
control stalk of the right (wiper) multi-function
switch toward the steering wheel to close the front
washer switch, check for battery voltage at the
washer pump switch sense circuit cavity of the left
headlamp and dash wire harness connector for the
front washer pump/motor unit. If OK, replace the
faulty front washer pump/motor. If not OK, repair
the open washer pump switch sense circuit between
the right (wiper) multi-function switch and the front
washer pump/motor unit as required.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the instrument panel wire harness con-
nector (Connector C2) for the Body Control Module
(BCM) from the BCM connector receptacle. Recon-
nect the battery negative cable. Turn the ignition
switch to the On position. While pulling the control
stalk of the right (wiper) multi-function switch
toward the steering wheel to close the front washer
WJFRONT WIPERS/WASHERS 8R - 7
FRONT WIPERS/WASHERS (Continued)

(3) Insert the hook formation on the tip of the
wiper arm through the opening in the wiper blade
superstructure ahead of the wiper blade pivot block/
latch unit far enough to engage the pivot block with
the hook (Fig. 10).
(4) Slide the wiper blade pivot block/latch up into
the hook formation on the tip of the wiper arm until
the latch release tab snaps into its locked position.
Latch engagement will be accompanied by an audible
click.
(5) Gently lower the wiper blade onto the glass.
FRONT WIPER MODULE
DESCRIPTION
The front wiper module is secured with four screws
through rubber isolators to the cowl plenum panel
beneath the cowl plenum cover/grille panel (Fig. 11).
The ends of the wiper pivot shafts that protrude
through dedicated openings in the cowl plenum cov-
er/grille panel to drive the wiper arms and blades are
the only visible components of the front wiper mod-
ule. The front wiper module consists of the following
major components:
²Bracket- The front wiper module bracket con-
sists of a long tubular steel main member that has a
stamped pivot bracket formation near each end
where the two wiper pivots are secured. A stamped
steel mounting plate for the wiper motor is secured
with welds near the center of the main member.
²Crank Arm- The front wiper motor crank arm
is a stamped steel unit with a slotted hole on the
driven end that is secured to the wiper motor outputshaft with a nut, and a ball stud secured to the drive
end.
²Linkage- Two stamped steel drive links con-
nect the wiper motor crank arm to the pivot lever
arms. The passenger side drive link has a plastic
socket-type bushing on each end. The driver side
drive link has a plastic socket-type bushing on one
end, and a plastic sleeve-type bushing on the other
end. The socket-type bushing on one end of each
drive link is snap-fit over the ball stud on the lever
arm of its respective pivot. The driver side drive link
sleeve-type bushing end is then fit over the motor
crank arm ball stud, and the other socket-type bush-
ing of the passenger side drive link is snap-fit over
the exposed end of the wiper motor crank arm ball
stud.
²Motor- The front wiper motor is secured with
three screws to the motor mounting plate near the
center of the wiper module bracket. The wiper motor
output shaft passes through a hole in the module
bracket, where a nut secures the wiper motor crank
arm to the motor output shaft. The two-speed perma-
nent magnet wiper motor features an integral trans-
mission, an internal park switch, and an internal
automatic resetting circuit breaker.
²Pivots- The two front wiper pivots are secured
to the ends of the wiper module bracket. The crank
arms that extend from the bottom of the pivot shafts
each have a ball stud on their end. The upper end of
each pivot shaft where the wiper arms will be fas-
tened each has an externally serrated drum with a
threaded stud secured to it.
The front wiper module cannot be adjusted or
repaired. If any component of the module is faulty or
damaged, the entire front wiper module unit must be
replaced. The reinforcement bracket and stud plate
are available for service replacement.OPERATION
The front wiper module operation is controlled by
the battery current inputs received by the wiper
motor from the wiper on/off and wiper high/low
relays. The wiper motor speed is controlled by cur-
rent flow to either the low speed or the high speed
set of brushes. The park switch is a single pole, sin-
gle throw, momentary switch within the wiper motor
that is mechanically actuated by the wiper motor
transmission components. The park switch alter-
nately closes the wiper park switch sense circuit to
ground or to battery current, depending upon the
position of the wipers on the glass. This feature
allows the motor to complete its current wipe cycle
after the wiper system has been turned Off, and to
park the wiper blades in the lowest portion of the
wipe pattern. The automatic resetting circuit breaker
protects the motor from overloads. The wiper motor
Fig. 11 Front Wiper Module
1 - FRONT WIPER MODULE
2 - SCREW (4)
3 - WIRE HARNESS CONNECTOR
4 - LOWER COWL PLENUM PANEL
8R - 16 FRONT WIPERS/WASHERSWJ
FRONT WIPER BLADE (Continued)

POWERTRAIN CONTROL MODULE C3 (GAS) - GRAY 32 WAY
CAV CIRCUIT FUNCTION
1 C13 18DB/OR A/C COMPRESSOR CLUTCH RELAY CONTROL
2- -
3 K51 18DB/YL AUTO SHUT DOWN RELAY CONTROL
4 V36 18TN/RD SPEED CONTROL VACUUM SOLENOID CONTROL
5 V35 18LG/RD SPEED CONTROL VENT SOLENOID CONTROL
6- -
7 K42 18DB/LG (4.7L HIGH OUTPUT) KNOCK SENSOR NO. 1 SIGNAL
8 K99 18BR/OR OXYGEN SENSOR 1/1 HEATER CONTROL
9 K512 18RD/YL (EXCEPT 4.0L
BUILT-UP-EXPORT)OXYGEN SENSOR DOWNSTREAM RELAY CONTROL
10 K106 18WT/DG (EXCEPT
BUILT-UP-EXPORT)LEAK DETECTION PUMP SOLENOID CONTROL
11 V32 18OR/DG SPEED CONTROL SUPPLY
12 F42 18DG/LG FUSED AUTO SHUT DOWN RELAY OUTPUT
13 T10 18YL/DG (4.7L RHD) TORQUE MANAGEMENT REQUEST SENSE
13 T6 18OR/WT (4.0L LHD) OVERDRIVE OFF SWITCH SENSE
13 T10 18DG/LG (4.7L LHD) TORQUE MANAGEMENT REQUEST SENSE
13 T6 18OR/BK (4.0L RHD) OVERDRIVE OFF SWITCH SENSE
14 K107 18OR/PK (EXCEPT
BUILT-UP-EXPORT)LEAK DETECTION PUMP SWITCH SENSE
15 K25 18VT/LG BATTERY TEMPERATURE SENSOR SIGNAL
16 K299 18BR/WT OXYGEN SENSOR 1/2 HEATER CONTROL
17 - -
18 K142 18GY/BK (4.7L HIGH OUTPUT) KNOCK SENSOR NO. 2 SIGNAL
19 K31 18BR FUEL PUMP RELAY CONTROL
20 K52 18PK/BK DUTY CYCLE EVAP/PURGE SOLENOID CONTROL
21 - -
22 - -
23 - -
24 K29 18WT/PK SECONDARY BRAKE SWITCH SIGNAL
25 K125 18WT/DB GENERATOR SOURCE
26 K226 18LB/YL FUEL LEVEL SENSOR SIGNAL
27 D21 18PK SCI TRANSMIT
28 - -
29 D32 18LG (LHD) SCI RECEIVE
29 D32 18LG/DG (RHD) SCI RECEIVE
30 D25 18VT/YL PCI BUS
31 - -
32 V37 18RD/LG SPEED CONTROL SWITCH SIGNAL
RADIATOR FAN MOTOR - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 C23 12DG RADIATOR FAN RELAY OUTPUT
2 Z4 12BK/PK GROUND
8W - 80 - 110 8W-80 CONNECTOR PIN-OUTWJ

The PCM uses the IAC motor to control idle speed
(along with timing) and to reach a desired MAP dur-
ing decel (keep engine from stalling).
The IAC motor has 4 wires with 4 circuits. Two of
the wires are for 12 volts and ground to supply elec-
trical current to the motor windings to operate the
stepper motor in one direction. The other 2 wires are
also for 12 volts and ground to supply electrical cur-
rent to operate the stepper motor in the opposite
direction.
To make the IAC go in the opposite direction, the
PCM just reverses polarity on both windings. If only
1 wire is open, the IAC can only be moved 1 step
(increment) in either direction. To keep the IAC
motor in position when no movement is needed, the
PCM will energize both windings at the same time.
This locks the IAC motor in place.
In the IAC motor system, the PCM will count
every step that the motor is moved. This allows the
PCM to determine the motor pintle position. If the
memory is cleared, the PCM no longer knows the
position of the pintle. So at the first key ON, the
PCM drives the IAC motor closed, regardless of
where it was before. This zeros the counter. From
this point the PCM will back out the IAC motor and
keep track of its position again.
When engine rpm is above idle speed, the IAC is
used for the following:
²Off-idle dashpot (throttle blade will close quickly
but idle speed will not stop quickly)
²Deceleration air flow control
²A/C compressor load control (also opens the pas-
sage slightly before the compressor is engaged so
that the engine rpm does not dip down when the
compressor engages)
²Power steering load control
The PCM can control polarity of the circuit to con-
trol direction of the stepper motor.
IAC Stepper Motor Program:The PCM is also
equipped with a memory program that records the
number of steps the IAC stepper motor most recently
advanced to during a certain set of parameters. For
example: The PCM was attempting to maintain a
1000 rpm target during a cold start-up cycle. The last
recorded number of steps for that may have been
125. That value would be recorded in the memory
cell so that the next time the PCM recognizes the
identical conditions, the PCM recalls that 125 steps
were required to maintain the target. This program
allows for greater customer satisfaction due to
greater control of engine idle.
Another function of the memory program, which
occurs when the power steering switch (if equipped),
or the A/C request circuit, requires that the IAC step-
per motor control engine rpm, is the recording of the
last targeted steps into the memory cell. The PCMcan anticipate A/C compressor loads. This is accom-
plished by delaying compressor operation for approx-
imately 0.5 seconds until the PCM moves the IAC
stepper motor to the recorded steps that were loaded
into the memory cell. Using this program helps elim-
inate idle-quality changes as loads change. Finally,
the PCM incorporates a9No-Load9engine speed lim-
iter of approximately 1800 - 2000 rpm, when it rec-
ognizes that the TPS is indicating an idle signal and
IAC motor cannot maintain engine idle.
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 IAC motor through the PCM.
REMOVAL
REMOVAL - 4.0L
The IAC motor is located on the throttle body.
(1) Remove air duct and air resonator box at throt-
tle body.
(2) Disconnect electrical connector from IAC motor
(Fig. 40).
(3) Remove two mounting bolts (screws) (Fig. 26).
(4) Remove IAC motor from throttle body.
REMOVAL - 4.7L
(1) Remove air duct and air resonator box at throt-
tle body.
(2) Disconnect electrical connector from IAC motor
(Fig. 36).
(3) Remove two mounting bolts (screws) (Fig. 42).
(4) Remove IAC motor from throttle body.
Fig. 26 Mounting Bolts (Screws)ÐIAC
1 - IDLE AIR CONTROL MOTOR
2 - MOUNTING SCREWS
WJFUEL INJECTION 14 - 45
IDLE AIR CONTROL MOTOR (Continued)

Normal calibration will be performed when sump
temperature is above 50 degrees F, or in the absence
of sump temperature data, after the first 10 minutes
of vehicle operation. Calibration of the pressure
transducer offset occurs each time the output shaft
speed falls below 200 RPM. Calibration shall be
repeated each 3 seconds the output shaft speed is
below 200 RPM. A 0.5 second pulse of 95% duty cycle
is applied to the governor pressure solenoid valve
and the transducer output is read during this pulse.
Averaging of the transducer signal is necessary to
reject electrical noise.
Under cold conditions (below 50 degrees F sump),
the governor pressure solenoid valve response may
be too slow to guarantee 0 psi during the 0.5 second
calibration pulse. Calibration pulses are continued
during this period, however the transducer output
valves are discarded. Transducer offset must be read
at key-on, under conditions which promote a stable
reading. This value is retained and becomes the off-
set during the9cold9period of operation.
GOVERNOR PRESSURE SOLENOID VALVE
The inlet side of the solenoid valve is exposed to
normal transmission line pressure. The outlet side of
the valve leads to the valve body governor circuit.
The solenoid valve regulates line pressure to pro-
duce governor pressure. The average current sup-
plied to the solenoid controls governor pressure. One
amp current produces zero kPa/psi governor pres-
sure. Zero amps sets the maximum governor pres-
sure.
The powertrain control module (PCM) turns on the
trans control relay which supplies electrical power to
the solenoid valve. Operating voltage is 12 volts
(DC). The PCM controls the ground side of the sole-
noid using the governor pressure solenoid control cir-
cuit.
GOVERNOR PRESSURE SENSOR
The sensor output signal provides the necessary
feedback to the PCM. This feedback is needed to ade-
quately control governor pressure.
GOVERNOR BODY AND TRANSFER PLATE
The transfer plate channels line pressure to the
solenoid valve through the governor body. It also
channels governor pressure from the solenoid valve
to the governor circuit. It is the solenoid valve that
develops the necessary governor pressure.
GOVERNOR PRESSURE CURVES
LOW TRANSMISSION FLUID TEMPERATURE
When the transmission fluid is cold the conven-
tional governor can delay shifts, resulting in higherthan normal shift speeds and harsh shifts. The elec-
tronically controlled low temperature governor pres-
sure curve is higher than normal to make the
transmission shift at normal speeds and sooner. The
PCM uses a temperature sensor in the transmission
oil sump to determine when low temperature gover-
nor pressure is needed.
NORMAL OPERATION
Normal operation is refined through the increased
computing power of the PCM and through access to
data on engine operating conditions provided by the
PCM that were not available with the previous
stand-alone electronic module. This facilitated the
development of a load adaptive shift strategy - the
ability to alter the shift schedule in response to vehi-
cle load condition. One manifestation of this capabil-
ity is grade9hunting9prevention - the ability of the
transmission logic to delay an upshift on a grade if
the engine does not have sufficient power to main-
tain speed in the higher gear. The 3-2 downshift and
the potential for hunting between gears occurs with a
heavily loaded vehicle or on steep grades. When
hunting occurs, it is very objectionable because shifts
are frequent and accompanied by large changes in
noise and acceleration.
WIDE OPEN THROTTLE OPERATION
In wide-open throttle (WOT) mode, adaptive mem-
ory in the PCM assures that up-shifts occur at the
preprogrammed optimum speed. WOT operation is
determined from the throttle position sensor, which
is also a part of the emission control system. The ini-
tial setting for the WOT upshift is below the opti-
mum engine speed. As WOT shifts are repeated, the
PCM learns the time required to complete the shifts
by comparing the engine speed when the shifts occur
to the optimum speed. After each shift, the PCM
adjusts the shift point until the optimum speed is
reached. The PCM also considers vehicle loading,
grade and engine performance changes due to high
altitude in determining when to make WOT shifts. It
does this by measuring vehicle and engine accelera-
tion and then factoring in the shift time.
TRANSFER CASE LOW RANGE OPERATION
On four-wheel drive vehicles operating in low
range, the engine can accelerate to its peak more
rapidly than in Normal range, resulting in delayed
shifts and undesirable engine9flare.9The low range
governor pressure curve is also higher than normal
to initiate upshifts sooner. The PCM compares elec-
tronic vehicle speed signal used by the speedometer
to the transmission output shaft speed signal to
determine when the transfer case is in low range.
21 - 66 AUTOMATIC TRANSMISSION - 42REWJ
ELECTRONIC GOVERNOR (Continued)

OVERDRIVE CLUTCH
DESCRIPTION
The overdrive clutch (Fig. 125) is composed of the
pressure plate, clutch plates, holding discs, overdrive
piston retainer, piston, piston spacer, and snap-rings.
The overdrive clutch is the forwardmost component
in the transmission overdrive unit and is considered
a holding component. The overdrive piston retainer,
piston, and piston spacer are located on the rear of
the main transmission case.
NOTE: The number of discs and plates may vary
with each engine and vehicle combination.
OPERATION
To apply the clutch, pressure is applied between
the piston retainer and piston. The fluid pressure is
provided by the oil pump, transferred through the
control valves and passageways, and enters the
clutch through passages at the lower rear portion of
the valve body area. With pressure applied between
the piston retainer and piston, the piston moves
away from the piston retainer and compresses the
clutch pack. This action applies the clutch pack,
allowing torque to flow through the intermediate
shaft into the overdrive planetary gear set. The over-
drive clutch discs are attached to the overdrive clutch
hub while the overdrive clutch plates, reaction plate,
and pressure plate are lugged to the overdrive hous-
ing. This allows the intermediate shaft to transferthe engine torque to the planetary gear and overrun-
ning clutch. This drives the planetary gear inside the
annulus, which is attached to the overdrive clutch
drum and output shaft, creating the desired gear
ratio. The waved snap-ring is used to cushion the
application of the clutch pack.
OVERDRIVE OFF SWITCH
DESCRIPTION
The overdrive OFF (control) switch is located in
the shifter handle. The switch is a momentary con-
tact device that signals the PCM to toggle current
status of the overdrive function.
OPERATION
At key-on, fourth gear operation is allowed. Press-
ing the switch once causes the overdrive OFF mode
to be entered and the overdrive OFF switch lamp to
be illuminated. Pressing the switch a second time
causes normal overdrive operation to be restored and
the overdrive lamp to be turned off. The overdrive
OFF mode defaults to ON after the ignition switch is
cycled OFF and ON. The normal position for the con-
trol switch is the ON position. The switch must be in
this position to energize the solenoid and allow
upshifts to fourth gear. The control switch indicator
light illuminates only when the overdrive switch is
turned to the OFF position, or when illuminated by
the powertrain control module.
Fig. 125 Overdrive Clutch
1 - REACTION PLATE 2 - PRESSURE PLATE
21 - 86 AUTOMATIC TRANSMISSION - 42REWJ

A solenoid can also be described by the method by
which it is controlled. Some of the possibilities
include variable force, pulse-width modulated, con-
stant ON, or duty cycle. The variable force and pulse-
width modulated versions utilize similar methods to
control the current flow through the solenoid to posi-
tion the solenoid plunger at a desired position some-
where between full ON and full OFF. The constant
ON and duty cycled versions control the voltage
across the solenoid to allow either full flow or no flow
through the solenoid's valve.
OPERATION
When an electrical current is applied to the sole-
noid coil, a magnetic field is created which produces
an attraction to the plunger, causing the plunger to
move and work against the spring pressure and the
load applied by the fluid the valve is controlling. The
plunger is normally directly attached to the valve
which it is to operate. When the current is removed
from the coil, the attraction is removed and the
plunger will return to its original position due to
spring pressure.
The plunger is made of a conductive material and
accomplishes this movement by providing a path for
the magnetic field to flow. By keeping the air gap
between the plunger and the coil to the minimum
necessary to allow free movement of the plunger, the
magnetic field is maximized.
SPEED SENSOR
DESCRIPTION
The speed sensor (Fig. 240) is located in the over-
drive gear case. The sensor is positioned over the
park gear and monitors transmission output shaft
rotating speed.
OPERATION
Speed sensor signals are triggered by the park
gear lugs as they rotate past the sensor pickup face.
Input signals from the sensor are sent to the trans-
mission control module for processing. Signals from
this sensor are shared with the powertrain control
module.
THROTTLE VALVE CABLE
DESCRIPTION
Transmission throttle valve cable adjustment is
extremely important to proper operation. This adjust-
ment positions the throttle valve, which controls shift
speed, quality, and part-throttle downshift sensitivity.
If cable setting is too loose, early shifts and slip-
page between shifts may occur. If the setting is too
tight, shifts may be delayed and part throttle down-
shifts may be very sensitive.
The transmission throttle valve is operated by a
cam on the throttle lever. The throttle lever is oper-
ated by an adjustable cable (Fig. 241). The cable is
attached to an arm mounted on the throttle lever
shaft. A retaining clip at the engine-end of the cable
is removed to provide for cable adjustment. The
retaining clip is then installed back onto the throttle
valve cable to lock in the adjustment.
ADJUSTMENTS - TRANSMISSION THROTTLE
VALVE CABLE
A correctly adjusted throttle valve cable (Fig. 242)
will cause the throttle lever on the transmission to
move simultaneously with the throttle body lever
from the idle position. Proper adjustment will allow
Fig. 240 Transmission Output Speed Sensor
1 - TRANSMISSION OUTPUT SHAFT SPEED SENSOR
2 - SEAL
Fig. 241 Throttle Valve Cable
1 - THROTTLE VALVE CABLE
2 - THROTTLE VALVE LEVER
3 - THROTTLE BODY
21 - 126 AUTOMATIC TRANSMISSION - 42REWJ
SOLENOID (Continued)

TRANSMISSION IDENTIFICATION
Transmission identification numbers are stamped
on the left side of the case just above the oil pan
sealing surface (Fig. 1). Refer to this information
when ordering replacement parts. A label is attached
to the transmission case above the stamped numbers.
The label gives additional information which may
also be necessary for identification purposes.
GEAR RATIOS The 545RFE gear ratios are:
1st .................................3.00:1
2nd.................................1.67:1
2nd Prime............................1.50:1
3rd .................................1.00:1
4th .................................0.75:1
5th .................................0.67:1
Reverse..............................3.00:1
OPERATION
The 545RFE offers full electronic control of all auto-
matic up and downshifts, and features real-time adap-
tive closed-loop shift and pressure control. Electronic
shift and torque converter clutch controls help protect
the transmission from damage due to high tempera-
tures, which can occur under severe operating condi-
tions. By altering shift schedules, line pressure, and
converter clutch control, these controls reduce heat gen-
eration and increase transmission cooling.
To help reduce efficiency-robbing parasitic losses,
the transmission includes a dual-stage transmission
fluid pump with electronic output pressure control.
Under most driving conditions, pump output pres-
sure greatly exceeds that which is needed to keep the
clutches applied. The 545RFE pump-pressure controlsystem monitors input torque and adjusts the pump
pressure accordingly. The primary stage of the pump
works continuously; the second stage is bypassed
when demand is low. The control system also moni-
tors input and output speed and, if incipient clutch
slip is observed, the pressure control solenoid duty
cycle is varied, increasing pressure in proportion to
demand.
A high-travel torque converter damper assembly
allows earlier torque converter clutch engagement to
reduce slippage. Needle-type thrust bearings reduce
internal friction. The 545RFE is packaged in a one-
piece die-cast aluminum case. To reduce NVH, the
case has high lateral, vertical and torsional stiffness.
It is also designed to maximize the benefit of the
structural dust cover that connects the bottom of the
bell housing to the engine bedplate, enhancing over-
all power train stiffness. Dual filters protect the
pump and other components. A pump return filter is
added to the customary main sump filter. Indepen-
dent lubrication and cooler circuits assure ample
pressure for normal transmission operation even if
the cooler is obstructed or the fluid cannot flow due
to extremely low temperatures.
The hydraulic control system design (without elec-
tronic assist) provides the transmission with PARK,
REVERSE, NEUTRAL, SECOND, and THIRD gears,
based solely on driver shift lever selection. This
design allows the vehicle to be driven (in ªlimp-inº
mode) in the event of a electronic control system fail-
ure, or a situation that the Transmission Control
Module (TCM) recognizes as potentially damaging to
the transmission.
The TCM also performs certain self-diagnostic
functions and provides comprehensive information
(sensor data, DTC's, etc.) which is helpful in proper
diagnosis and repair. This information can be viewed
with the DRB scan tool.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - AUTOMATIC
TRANSMISSION
CAUTION: Before attempting any repair on a
545RFE automatic transmission, check for Diagnos-
tic Trouble Codes with the DRBTscan tool.
Transmission malfunctions may be caused by these
general conditions:
²Poor engine performance
²Improper adjustments
²Hydraulic malfunctions
²Mechanical malfunctions
²Electronic malfunctions
Fig. 1 Transmission Part And Serial Number
Location
WJAUTOMATIC TRANSMISSION - 545RFE 21 - 179
AUTOMATIC TRANSMISSION - 545RFE (Continued)

OUTPUT SPEED SENSOR
DESCRIPTION
The Input and Output Speed Sensors are two-wire
magnetic pickup devices that generate AC signals as
rotation occurs. They are mounted in the left side of
the transmission case and are considered primary
inputs to the Transmission Control Module (TCM).
OPERATION
The Input Speed Sensor provides information on
how fast the input shaft is rotating. As the teeth of
the input clutch hub pass by the sensor coil, an AC
voltage is generated and sent to the TCM. The TCM
interprets this information as input shaft rpm.
The Output Speed Sensor generates an AC signal
in a similar fashion, though its coil is excited by rota-
tion of the rear planetary carrier lugs. The TCM
interprets this information as output shaft rpm.
The TCM compares the input and output speed
signals to determine the following:
²Transmission gear ratio
²Speed ratio error detection
²CVI calculation
The TCM also compares the input speed signal and
the engine speed signal to determine the following:
²Torque converter clutch slippage
²Torque converter element speed ratio
REMOVAL
(1) Raise vehicle.
(2) Place a suitable fluid catch pan under the
transmission.
(3) Remove the wiring connector from the output
speed sensor (Fig. 96).
(4) Remove the bolt holding the output speed sen-
sor to the transmission case.
(5) Remove the output speed sensor from the
transmission case.
INSTALLATION
(1) Install the output speed sensor into the trans-
mission case.
(2) Install the bolt to hold the output speed sensor
into the transmission case. Tighten the bolt to 11.9
N´m (105 in.lbs.).
(3) Install the wiring connector onto the output
speed sensor
(4) Verify the transmission fluid level. Add fluid as
necessary.
(5) Lower vehicle.
OVERDRIVE SWITCH
DESCRIPTION
The overdrive OFF (control) switch is located in
the shifter handle. The switch is a momentary con-
tact device that signals the PCM to toggle current
status of the overdrive function.
OPERATION
At key-on, fourth and fifth gear operation is
allowed. Pressing the switch once causes the over-
drive OFF mode to be entered and the overdrive OFF
switch lamp to be illuminated. Pressing the switch a
second time causes normal overdrive operation to be
restored and the overdrive lamp to be turned off. The
overdrive OFF mode defaults to ON after the ignition
switch is cycled OFF and ON. The normal position
for the control switch is the ON position. The switch
must be in this position to energize the solenoids and
allow upshifts to fourth and fifth gears. The control
switch indicator light illuminates only when the over-
drive switch is turned to the OFF position, or when
illuminated by the transmission control module.
Fig. 96 Output Speed Sensor
1 - OUTPUT SPEED SENSOR
2 - LINE PRESSURE SENSOR
3 - INPUT SPEED SENSOR
21 - 254 AUTOMATIC TRANSMISSION - 545RFEWJ