Transmission control system DODGE RAM 2002 Service Manual PDF

CONDITION POSSIBLE CAUSES CORRECTION
BUZZING NOISE 1. Fluid Level Low 1. Add fluid and check for leaks.
2. Shift Cable Mis-assembled. 2. Route cable away from engine and bell
housing.
3. Valve Body Mis-assembled. 3. Remove, disassemble, inspect valve
body. Reassemble correctly if necessary.
Replace assembly if valves or springs are
damaged. Check for loose bolts or screws.
4. Pump Passages Leaking. 4. Check pump for porous casting, scores
on mating surfaces and excess rotor
clearance. Repair as required. Loose pump
bolts.
5. Cooling System Cooler Plugged. 5. Flow check cooler circuit. Repair as
needed.
6. Overrunning Clutch Damaged. 6. Replace clutch.
SLIPS IN REVERSE ONLY 1. Fluid Level Low. 1. Add fluid and check for leaks.
2. Gearshift Linkage Mis-adjusted. 2. Adjust linkage.
3. Rear Band Mis-adjusted. 3. Adjust band.
4. Rear Band Worn. 4. Replace as required.
5. Overdrive Direct Clutch Worn. 5. Disassemble overdrive. Repair as
needed.
6. Hydraulic Pressure Too Low. 6. Perform hydraulic pressure tests to
determine cause.
7. Rear Servo Leaking. 7. Air pressure check clutch-servo operation
and repair as required.
8. Band Linkage Binding. 8. Inspect and repair as required.
SLIPS IN FORWARD
DRIVE RANGES1. Fluid Level Low. 1. Add fluid and check for leaks.
2. Fluid Foaming. 2. Check for high oil level, bad pump
gasket or seals, dirt between pump halves
and loose pump bolts. Replace pump if
necessary.
3. Throttle Linkage Mis-adjusted. 3. Adjust linkage.
4. Gearshift Linkage Mis-adjusted. 4. Adjust linkage.
5. Rear Clutch Worn. 5. Inspect and replace as needed.
6. Low Hydraulic Pressure Due to
Worn Pump, Incorrect Control
Pressure Adjustments, Valve Body
Warpage or Malfunction, Sticking,
Leaking Seal Rings, Clutch Seals
Leaking, Servo Leaks, Clogged Filter
or Cooler Lines.6. Perform hydraulic and air pressure tests
to determine cause.
7. Rear Clutch Malfunction, Leaking
Seals or Worn Plates.7. Air pressure check clutch-servo operation
and repair as required.
8. Overrunning Clutch Worn, Not
Holding (Slips in 1 Only).8. Replace Clutch.
SLIPS IN LOW GEAR9D9
ONLY, BUT NOT IN
MANUAL 1 POSITIONOverrunning Clutch Faulty. Replace overrunning clutch.
BR/BEAUTOMATIC TRANSMISSION - 47RE 21 - 279
AUTOMATIC TRANSMISSION - 47RE (Continued)

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.
REMOVAL
(1) Hoist and support vehicle on safety stands.
(2) Remove transmission fluid pan and filter.
(3) Disengage wire connectors from pressure sen-
sor and solenoid (Fig. 71).
(4) Remove screws holding pressure solenoid
retainer to governor body.
(5) Separate solenoid retainer from governor (Fig.
72).
(6) Pull solenoid from governor body (Fig. 73).
(7) Pull pressure sensor from governor body.
(8) Remove bolts holding governor body to valve
body.
(9) Separate governor body from valve body (Fig.
74).
(10) Remove governor body gasket.
INSTALLATION
Before installing the pressure sensor and solenoid
in the governor body, replace o-ring seals, clean the
gasket surfaces and replace gasket.
(1) Place gasket in position on back of governor
body (Fig. 75).
(2) Place governor body in position on valve body.
(3) Install bolts to hold governor body to valve
body.
(4) Lubricate o-ring on pressure sensor with trans-
mission fluid.
(5) Align pressure sensor to bore in governor body.
(6) Push pressure sensor into governor body.
(7) Lubricate o-ring, on pressure solenoid, with
transmission fluid.
Fig. 71 Governor Solenoid And Pressure Sensor
1 - PRESSURE SENSOR
2 - PRESSURE SOLENOID
3 - GOVERNOR
Fig. 72 Pressure Solenoid Retainer
1 - PRESSURE SOLENOID RETAINER
2 - GOVERNOR
21 - 324 AUTOMATIC TRANSMISSION - 47REBR/BE
ELECTRONIC GOVERNOR (Continued)

CHECK BALLS
CHECK BALL NUMBER DESCRIPTION
1 Allows either the manual valve to put line pressure on the 1-2 governor plug or
the KD Valve to put WOT line pressure on the 1-2 governor plug.
2 Allows either the manual valve to put line pressure on the 2-3 governor plug or
the KD Valve to put WOT line pressure on the 2-3 governor plug.
3 Allows either the Reverse circuit or the 3rd gear circuit to pressurize the front
clutch.
4 Allows either the Manual Low circuit from the Manual Valve or the Reverse
from the Manual Valve circuit to pressurize the rear servo.
5 Directs line pressure to the spring end of the 2-3 shift valve in either Manual
Low or Manual 2nd, forcing the downshift to 2nd gear regardless of governor
pressure.
6 Provides a by-pass around the front servo orifice so that the servo can release
quickly.
7 Provides a by-pass around the rear clutch orifice so that the clutch can release
quickly.
8 Directs reverse line pressure through an orifice to the throttle valve eliminating
the extra leakage and insuring that Reverse line pressure pressure will be
sufficient.
9 Provides a by-pass around the rear servo orifice so that the servo can release
quickly.
ECE (10) Allows the lockup clutch to used at WOT in 3rd gear by putting line pressure
from the 3-4 Timing Valve on the interlock area of the 2-3 shift valve, thereby
preventing a 3rd gear Lock-up to 2nd gear kickdown.
REGULATOR VALVE
The pressure regulator valve is needed to control
the hydraulic pressure within the system and reduce
the amount of heat produced in the fluid. The pres-
sure regulator valve is located in the valve body near
the manual valve. The pressure regulator valve train
controls the maximum pressure in the lines by
metering the dumping of fluid back into the sump.
Regulated pressure is referred to as ªline pressure.º
BR/BEAUTOMATIC TRANSMISSION - 47RE 21 - 395
VALVE BODY (Continued)

INSTRUMENT PANEL SYSTEM
TABLE OF CONTENTS
page page
INSTRUMENT PANEL SYSTEM
DESCRIPTION........................105
OPERATION..........................106
ASH RECEIVER
REMOVAL............................107
INSTALLATION........................107
CLUSTER BEZEL
REMOVAL............................108
INSTALLATION........................108
CUBBY BIN
REMOVAL............................108
INSTALLATION........................109
CUP HOLDER
REMOVAL............................109
INSTALLATION........................110
GLOVE BOX
REMOVAL
REMOVAL..........................110
DISASSEMBLY - GLOVE BOX...........110
ASSEMBLY - GLOVE BOX................111INSTALLATION........................111
GLOVE BOX LATCH STRIKER
REMOVAL............................111
INSTALLATION........................112
GLOVE BOX OPENING UPPER TRIM
REMOVAL............................112
INSTALLATION........................112
INSTRUMENT PANEL TOP COVER
REMOVAL............................113
INSTALLATION........................113
STEERING COLUMN OPENING COVER
REMOVAL............................113
INSTALLATION........................114
STORAGE BIN
REMOVAL............................114
INSTALLATION........................114
INSTRUMENT PANEL ASSEMBLY
REMOVAL............................115
INSTALLATION........................117
INSTRUMENT PANEL SYSTEM
DESCRIPTION
The instrument panel is located at the front of the
passenger compartment. This instrument panel is
molded from a blend of various plastics that are
mechanically attached to the vehicle. Colors are
molded into the plastic components to minimize
appearance degradation from scratches or abrasions.
The panel components are internally ribbed and riv-
eted to steel reinforcements for additional structural
integrity and dimensional stability. The instrument
panel surface components are designed to deform
upon impact without breaking. This type of construc-
tion provides improved energy absorption which, in
conjunction with the dual airbags and seat belts,
helps to improve occupant protection.
The top of the instrument panel is secured to the
top of the dash panel near the base of the windshield
using screws. An end bracket integral to each end of
the instrument panel structure is secured to each
cowl side inner panel with a screw. A stamped metal
bracket supports the center of the instrument panel
by securing it to the top of the floor panel transmis-
sion tunnel below the instrument panel with screws.
The instrument cluster, radio, heater-air conditioner
control, passenger airbag, glove box, electrical junc-tion block, Central Timer Module (CTM), accessory
switches, ash receiver, cigar lighter, accessory power
outlet, park brake release handle, inside hood release
handle, as well as numerous other components are
secured to and supported by this unit.
The instrument panel for this vehicle includes the
following major features:
²Cluster Bezel- This molded plastic bezel is
secured with snap clips to the instrument panel sup-
porting structure. It trims out the edges of the head-
lamp switch, instrument cluster, radio, heater-air
conditioner controls, passenger airbag on-off switch,
and the heated seat switches on vehicles so equipped.
On vehicles without the heated seat option, a small
storage cubby bin is provided in the cluster bezel.
This bezel also incorporates three completely adjust-
able panel outlets for the climate control system, and
fills the opening between the instrument cluster and
the top of the steering column where it passes
through the instrument panel.
²Cup Holder/Storage Bin- Vehicles equipped
with an automatic transmission feature a latching
fold-down, adjustable cup holder located on the lower
instrument panel between the glove box and the ash
receiver. Vehicles equipped with a manual transmis-
sion have a lighted storage bin on the instrument
panel in place of the cup holder.
BR/BEINSTRUMENT PANEL SYSTEM 23 - 105

²Glove Box- The hinged bin-type glove box in
the passenger side of the instrument panel features a
recessed paddle-operated latch handle. Three molded
hook formations on the lower edge of the glove box
door are engaged with and pivot on three hinge pins
integral to the lower edge of the instrument panel
support structure. The glove box door also serves as
the passenger side knee blocker. A honeycomb struc-
ture between the inner and outer glove box door pan-
els helps to absorb the impact load and distribute it
to the instrument panel structure.
²Steering Column Opening Cover- The steer-
ing column opening cover serves as the driver side
knee blocker. This molded plastic cover has an inte-
gral ribbed plastic liner concealed behind it, for
increased strength and integrity. The steering column
opening cover transfers impact loads to the instru-
ment panel structural support.
²Top Cover- The instrument panel top cover or
base trim is the molded, grained, and color impreg-
nated plastic outer skin of the instrument panel
structural support.
Hard wired circuitry connects the electrical compo-
nents on the instrument panel to each other through
the electrical system of the vehicle. These hard wired
circuits are integral to several wire harnesses, which
are routed throughout the vehicle and retained by
many different methods. These circuits may be con-
nected to each other, to the vehicle electrical system
and to the instrument panel components through the
use of a combination of soldered splices, splice block
connectors and many different types of wire harness
terminal connectors and insulators. Refer to the
appropriate wiring information. The wiring informa-
tion includes complete circuit diagrams, proper wire
and connector repair procedures, further details on
wire harness routing and retention, as well as pin-
out and location views for the various wire harness
connectors, splices, and grounds.
OPERATION
The instrument panel serves as the command cen-
ter of the vehicle, which necessarily makes it a very
complex unit. The instrument panel is designed to
house the controls and monitors for standard and
optional powertrains, climate control systems, audio
systems, safety systems, and many other comfort or
convenience items. When the components of the
instrument panel structural support are properly
assembled and secured in the vehicle they provide
superior instrument panel stiffness and integrity to
help reduce buzzes, squeaks, and rattles. This type of
construction also provides improved energy absorp-
tion which, in conjunction with the dual airbags and
seat belts, helps to improve occupant protection.The instrument panel is also designed so that all of
the various controls can be safely reached and the
monitors can be easily viewed by the vehicle operator
when driving, while still allowing relative ease of
access to each of these items for service. Modular
instrument panel construction allows all of the
gauges and controls to be serviced from the front of
the panel. In addition, most of the instrument panel
electrical components can be accessed without com-
plete instrument panel removal. However, if neces-
sary, the instrument panel can be removed from the
vehicle as an assembly.
The steering column opening cover with its inte-
gral knee blocker located on the driver side of the
instrument panel works in conjunction with the air-
bag system in a frontal vehicle impact to keep the
driver properly positioned for an airbag deployment.
In addition, removal of this component provides
access to the steering column mounts, the steering
column wiring, the Junction Block (JB) (removal of a
snap-fit fuse access panel on the left end of the
instrument panel allows access to the fuses and cir-
cuit breakers), the Central Timer Module (CTM), the
Infinity speaker filter choke and relay unit, much of
the instrument panel wiring, and the gear selector
indicator cable (automatic transmission).
In a frontal collision, the glove box door on the pas-
senger side of the instrument panel provides the
same function for the front seat passenger as the
knee blocker does for the driver. The glove box door
also incorporates a recessed latch handle. Removal of
the glove box provides access to the passenger airbag,
the glove box lamp and switch, the radio antenna
coaxial cable, the heating and air conditioning vac-
uum harness connector, and additional instrument
panel wiring.
Removal of the instrument panel cluster bezel
allows access to the headlamp switch, instrument
cluster, radio, passenger airbag on-off switch, heated
seat switches (if equipped), and the heating and air
conditioning control. Removal of the instrument clus-
ter allows access to the cluster illumination and indi-
cator bulbs, and more of the instrument panel
wiring. Complete instrument panel removal is
required for service of most components internal to
the heating and air conditioning system housing,
including the heater core and the evaporator.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of all of the components and systems mounted on or
in the instrument panel.
23 - 106 INSTRUMENT PANEL SYSTEMBR/BE
INSTRUMENT PANEL SYSTEM (Continued)

instrument panel just inboard of the glove box. Vehi-
cles equipped with a manual transmission have a
lighted storage bin installed on the instrument panel
in place of the fold-down cup holder.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
(1) Position the storage bin unit onto the instru-
ment panel (Fig. 10).
(2) Engage the illumination lamp and hood
retainer clip to the back of the instrument panel stor-
age bin unit.
(3) Raise and position the top of the storage bin to
the instrument panel.
(4) Install and tighten the two screws that secure
the top of the storage bin unit to the instrument
panel. Tighten the screws to 2.2 N´m (20 in. lbs.).
(5) Reinstall the cluster bezel onto the instrument
panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
CLUSTER BEZEL - INSTALLATION).
(6) Reconnect the battery negative cable.
INSTRUMENT PANEL
ASSEMBLY
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPT-
ING ANY STEERING WHEEL, STEERING COLUMN,
SEAT BELT TENSIONER, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT
AND ISOLATE THE BATTERY NEGATIVE (GROUND)
CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG
SYSTEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS IS
THE ONLY SURE WAY TO DISABLE THE AIRBAG SYS-
TEM. FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT AND POSSIBLE PERSONAL INJURY.
NOTE: Before starting this procedure, be certain to
turn the steering wheel until the front wheels are in
the straight-ahead position.
(1)
Disconnect and isolate the battery negative cable.
(2) Remove the Airbag Control Module (ACM) and
bracket from the floor panel transmission tunnel.
(Refer to 8 - ELECTRICAL/RESTRAINTS/AIRBAG
CONTROL MODULE - REMOVAL).
(3) Remove the trim from the left and right cowl
side inner panels. (Refer to 23 - BODY/INTERIOR/
COWL TRIM COVER - REMOVAL).
(4) Remove the steering column opening cover
from the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT PANEL/STEERING COLUMN OPEN-
ING COVER - REMOVAL).
(5)
Remove the two screws that secure the inside
hood latch release handle to the instrument panel lower
reinforcement and lower the release handle to the floor.
(6)Disconnect the clockspring pigtail wire connector
from the instrument panel wire harness connector
located on the instrument panel lower reinforcement.
(7) If the vehicle is so equipped, disconnect the
overdrive lockout switch pigtail wire connector from
the instrument panel wire harness connector near
the instrument panel lower reinforcement.
(8) Remove the steering column from the vehicle,
but do not remove the driver airbag, the steering
wheel, or the switches from the column. Be certain
that the steering wheel is locked and secured from
rotation to prevent the loss of clockspring centering.
(Refer to 19 - STEERING/COLUMN - REMOVAL).
(9) From under the driver side of the instrument
panel, perform the following:
(a) Disengage the park brake release handle
linkage rod from the park brake mechanism on the
Fig. 10 Instrument Panel Storage Bin Remove/Install
1 - SCREWS
2 - STORAGE BIN (RAISED)
3 - STORAGE BIN (LOWERED)
BR/BEINSTRUMENT PANEL SYSTEM 23 - 115
STORAGE BIN (Continued)

wire harness connectors from the heater-A/C housing
wire harness connectors.
(15) With the aid of an assistant, remove the tem-
porary hook and lift the instrument panel assembly
off of the roll-down bracket screws and remove it
from the vehicle.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPT-
ING ANY STEERING WHEEL, STEERING COLUMN,
SEAT BELT TENSIONER, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT
AND ISOLATE THE BATTERY NEGATIVE (GROUND)
CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG
SYSTEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS IS
THE ONLY SURE WAY TO DISABLE THE AIRBAG SYS-
TEM. FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT AND POSSIBLE PERSONAL INJURY.
(1)With the aid of an assistant, load the instrument
panel assembly onto the roll-down bracket screws on
the cowl side inner panels in the vehicle (Fig. 11).
Install a temporary hook in the center hole on top of the
instrument panel. Secure the other end of the hook to
the center hole in the top of the dash panel. The hook
should support the instrument panel in its rolled down
position about 46 cm (18 inches) from the dash panel.
(2) With the instrument panel supported in the
roll-down position, reconnect the instrument panel
wire harness connectors to the heater-A/C housing
wire harness connectors.
(3) Remove the temporary hook from the instru-
ment panel and roll the instrument panel up to its
installed position against the dash panel.
(4) Install and tighten the five screws that secure
the top of the instrument panel to the top of the dash
panel. Tighten the screws to 3.2 N´m (28 in. lbs.).
(5) Tighten the right and left instrument panel
cowl side roll-down bracket screws. Tighten the
screws to 11.9 N´m (105 in. lbs.).
(6) From under the passenger side of the instru-
ment panel, reconnect the two halves of the radio
antenna coaxial cable connector.
(7) From under the driver side of the instrument
panel, perform the following:
(a) Engage the park brake release handle link-
age rod with the park brake mechanism on the left
cowl side inner panel. (Refer to 5 - BRAKES/PARK-
ING BRAKE/RELEASE - INSTALLATION).
(b) Reconnect the instrument panel wire harness
connector to the park brake switch on the park
brake mechanism.(c) Reconnect the three connectors (one from the
body wire harness, and two from the headlamp and
dash wire harness) to the three connector recepta-
cles located closest to the dash panel on the back of
the Junction Block (JB).
(d)
Reconnect the headlamp and dash wire harness
to instrument panel wire harness bulkhead connector
and tighten the screw in the center of the connector.
Tighten the screw to 3.5 N´m (31 in. lbs.).
(e) Reconnect the instrument panel wire harness
to door wire harness connector located directly
below the instrument panel wire harness to head-
lamp and dash wire harness bulkhead connector.
(f) If the vehicle is equipped with the Infinity
sound system option, reconnect the Infinity wire
harness connector to the instrument panel wire
harness connector that is secured to the outboard
side of the instrument panel wire harness to head-
lamp and dash wire harness bulkhead connector.
(g) Reconnect the instrument panel wire harness
connector to the stop lamp switch.
(h) Reconnect the heater-A/C housing vacuum
harness connector to the heater-A/C control vac-
uum harness connector located near the left end of
the heater-A/C housing.
(8) Reinstall the steering column into the vehicle.
Be certain that the steering wheel was locked and
secured from rotation to prevent the loss of clock-
spring centering. (Refer to 19 - STEERING/COL-
UMN - INSTALLATION).
(9) If the vehicle is so equipped, reconnect the
overdrive lockout switch pigtail wire connector to the
instrument panel wire harness connector near the
instrument panel lower reinforcement.
(10) Reconnect the clockspring pigtail wire connec-
tor to the instrument panel wire harness connector
at the instrument panel lower reinforcement.
(11) Position the inside hood latch release handle
to the instrument panel lower reinforcement.
(12) Install and tighten the two screws that secure
the inside hood latch release handle to the instru-
ment panel lower reinforcement. Tighten the screws
to 2.8 N´m (25 in. lbs.).
(13) Reinstall the steering column opening cover
onto the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT PANEL/STEERING COLUMN OPEN-
ING COVER - INSTALLATION).
(14) Reinstall the trim onto the left and right cowl
side inner panels. (Refer to 23 - BODY/INTERIOR/
COWL TRIM COVER - INSTALLATION).
(15) Reinstall the Airbag Control Module (ACM)
and bracket onto the floor panel transmission tunnel.
(Refer to 8 - ELECTRICAL/RESTRAINTS/AIRBAG
CONTROL MODULE - INSTALLATION).
(16) Reconnect the battery negative cable.
BR/BEINSTRUMENT PANEL SYSTEM 23 - 117
INSTRUMENT PANEL ASSEMBLY (Continued)

(3) On vehicles with air conditioning, turn the
temperature control knob to the extreme counter
clockwise (Cool) position, and set the mode control
switch knob to the Bi-Level (A/C) position. The out-
side (recirculation) air door should be open to outside
air. If not OK, (Refer to 24 - HEATING & AIR CON-
DITIONING/CONTROLS - DIAGNOSIS AND TEST-
ING - VACUUM SYSTEM).
(4) Open the vehicle windows. Test the blower
motor operation in all speeds. If not OK, (Refer to 24
- HEATING & AIR CONDITIONING/DISTRIBU-
TION/BLOWER MOTOR - DIAGNOSIS AND TEST-
ING).
(5) On vehicles with air conditioning, the compres-
sor should be running and the air conditioning sys-
tem in operation unless the ambient air temperature
is below about -1É C (30É F). If not OK, (Refer to 24 -
HEATING & AIR CONDITIONING - DIAGNOSIS
AND TESTING - A/C PERFORMANCE).
(6) Check the mode control switch operation. The
heater and air conditioner systems should respond as
described in the owner's manual in the vehicle glove
box to each mode selected. Reduce the engine speed
to normal idle. The vacuum will be high at low idle
and the vacuum actuators should respond quickly. If
not OK, (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS - DIAGNOSIS AND TEST-
ING - VACUUM SYSTEM).
(7) If the vacuum tests, and the electrical compo-
nent and circuit tests reveal no problems, disassem-
ble the HVAC housing to inspect for mechanical
misalignment or binding of the mode doors (Refer to
24 - HEATING & AIR CONDITIONING/DISTRIBU-
TION/HVAC HOUSING - DISASSEMBLY)
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Reach under the instrument panel near the
driver side of the floor panel transmission tunnel andunplug the a/c heater control to HVAC housing vac-
uum harness connector.
(3) While still reaching under the instrument
panel, disengage the retainer on the a/c heater con-
trol half of the vacuum harness from the hole in the
center distribution duct (Fig. 18).
(4) Remove the cluster bezel from the instrument
panel(Refer to 23 - BODY/INSTRUMENT PANEL/
CLUSTER BEZEL - REMOVAL).
(5) Remove the four screws that secure the a/c
heater control to the instrument panel (Fig. 19).
(6) Pull the a/c heater control assembly away from
the instrument panel far enough to access the con-
nections on the back of the control.
(7) Unplug the wire harness connector from the
back of the a/c heater control.
(8) On vehicles with heated mirrors, unplug the
heated mirror wire harness connector from the back
of the a/c heater control.
(9) Remove the a/c heater control from the instru-
ment panel.
INSTALLATION
(1) Plug the wire harness connector(s) into the
receptacle(s) on the back of the a/c heater control.
(2) Route the HVAC vacuum harness through the
hole in the reinforcement below the a/c heater control
opening of the instrument panel.
(3) Position the a/c heater control in the instru-
ment panel and secure it with four screws. Tighten
the screws to 2.2 N´m (20 in. lbs.).
Fig. 18 A/C HEATER CONTROL VACUUM HARNESS
ROUTING
1 - A/C HEATER CONTROL VACUUM HARNESS
2 - REINFORCEMENT
3 - RETAINER
4 - CENTER DISTRIBUTION DUCT
BR/BECONTROLS 24 - 19
A/C-HEATER CONTROL (Continued)

replaced. The compressor clutch, pulley and clutch
coil are available for service.
OPERATION - HIGH PRESSURE RELIEF VALVE
The high pressure relief valve vents the system
when a discharge pressure of 3445 to 4135 kPa (500
to 600 psi) or above is reached. The valve closes with
a minimum discharge pressure of 2756 kPa (400 psi)
is reached.
The high pressure relief valve vents only enough
refrigerant to reduce the system pressure, and then
re-seats itself. The majority of the refrigerant is con-
served in the system. If the valve vents refrigerant, it
does not mean the valve is faulty.
The high pressure relief valve is a factory-cali-
brated unit. The valve cannot be adjusted or
repaired, and must not be removed or otherwise dis-
turbed. The valve is only serviced as a part of the
compressor assembly.
DIAGNOSIS AND TESTING - A/C COMPRESSOR
When investigating an air conditioning related
noise, you must first know the conditions under
which the noise occurs. These conditions include:
weather, vehicle speed, transmission in gear or neu-
tral, engine speed, engine operating temperature,
and any other special conditions. Noises that develop
during air conditioning operation can often be mis-
leading. For example: What sounds like a failed front
bearing or connecting rod, may be caused by loose
bolts, nuts, mounting brackets, or a loose compressor
clutch assembly.
Drive belts are speed sensitive. At different engine
speeds and depending upon belt tension, belts can
develop noises that are mistaken for a compressor
noise. Improper belt tension can cause a misleading
noise when the compressor clutch is engaged, which
may not occur when the compressor clutch is disen-
gaged. Check the serpentine drive belt condition and
tension before beginning this procedure(Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
DIAGNOSIS AND TESTING).
(1) Select a quiet area for testing. Duplicate the
complaint conditions as much as possible. Switch the
compressor on and off several times to clearly iden-
tify the compressor noise. Listen to the compressor
while the clutch is engaged and disengaged. Probe
the compressor with an engine stethoscope or a long
screwdriver with the handle held to your ear to bet-
ter localize the source of the noise.
(2) Loosen all of the compressor mounting hard-
ware and retighten. Tighten the compressor clutch
mounting nut. Be certain that the clutch coil is
mounted securely to the compressor, and that the
clutch plate and pulley are properly aligned and have
the correct air gap. (Refer to 24 - HEATING & AIRCONDITIONING/CONTROLS/A/C COMPRESSOR
CLUTCH - INSTALLATION)
(3) To duplicate a high-ambient temperature condi-
tion (high head pressure), restrict the air flow
through the condenser. Install a manifold gauge set
to be certain that the discharge pressure does not
exceed 2760 kPa (400 psi).
(4) Check the refrigerant system plumbing for
incorrect routing, rubbing or interference, which can
cause unusual noises. Also check the refrigerant lines
for kinks or sharp bends that will restrict refrigerant
flow, which can cause noises. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAU-
TION)
(5) If the noise is from opening and closing of the
high pressure relief valve, recover, evacuate, and
recharge the refrigerant system. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT RECOVERY)
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - STANDARD PROCEDURE - REFRIG-
ERANT SYSTEM EVACUATE) (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE) If the high pressure relief valve still
does not seat properly, replace the compressor.
(6) If the noise is from liquid slugging on the suc-
tion line, replace the accumulator. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/AC-
CUMULATOR - REMOVAL) Check the refrigerant oil
level and the refrigerant system charge. (Refer to 24
- HEATING & AIR CONDITIONING/PLUMBING/
REFRIGERANT OIL - STANDARD PROCEDURE -
REFRIGERANT OIL LEVEL) (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - SPECI-
FICATIONS - CHARGE CAPACITY) If the liquid
slugging condition continues following accumulator
replacement, replace the compressor.
(7) If the noise continues, replace the compressor
and repeat Step 1.
REMOVAL
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
The compressor may be removed and repositioned
without disconnecting the refrigerant lines or dis-
charging the refrigerant system. Discharging is not
necessary if servicing the compressor clutch or clutch
coil, the engine, the cylinder head, or the generator.
(1) Recover the refrigerant from the refrigerant
system. (Refer to 24 - HEATING & AIR CONDI-
BR/BEPLUMBING 24 - 47
A/C COMPRESSOR (Continued)

EMISSIONS CONTROL
TABLE OF CONTENTS
page page
EMISSIONS CONTROL
DESCRIPTION
DESCRIPTION - DIESEL.................1
DESCRIPTION - STATE DISPLAY TEST
MODE...............................1
DESCRIPTION - CIRCUIT ACTUATION TEST
MODE...............................2
DESCRIPTION - DIAGNOSTIC TROUBLE
CODES..............................2
DESCRIPTION - TASK MANAGER.........17
DESCRIPTION - MONITORED SYSTEMS . . . 17
DESCRIPTION - TRIP DEFINITION........19
DESCRIPTION - COMPONENT MONITORS -
GAS ENGINES.......................19DESCRIPTION - COMPONENT MONITORS -
DIESEL ENGINES.....................20
OPERATION
OPERATION - GAS ENGINES............20
OPERATION - DIESEL..................20
OPERATION - TASK MANAGER..........21
OPERATION - NON-MONITORED
CIRCUITS - GAS ENGINES..............24
OPERATION - NON-MONITORED
CIRCUITS - DIESEL....................24
AIR INJECTION.........................26
EVAPORATIVE EMISSIONS................32
EMISSIONS CONTROL
DESCRIPTION
DESCRIPTION - DIESEL
Two different modules are used for powertrain con-
trol with the diesel engine. The Powertrain Control
Module (PCM) is used primarily for charging system,
transmission, A/C compressor clutch operation and
speed control functions. The Engine Control Module
(ECM) is used to control thefuel and emissions
systems.The PCM is located in the right/rear of
engine compartment (Fig. 1). The ECM is bolted to
the left side of the engine cylinder block (Fig. 2).
DESCRIPTION - STATE DISPLAY TEST MODE
The switch inputs to the Powertrain Control Mod-
ule (PCM) have two recognized states; HIGH and
LOW. For this reason, the PCM cannot recognize the
difference between a selected switch position versus
an open circuit, a short circuit, or a defective switch.
If the State Display screen shows the change from
HIGH to LOW or LOW to HIGH, assume the entire
switch circuit to the PCM functions properly. Connectthe DRB scan tool to the data link connector and
access the state display screen. Then access either
State Display Inputs and Outputs or State Display
Sensors.
Fig. 1 Powertrain Control Module (PCM) Location
1 - PCM MOUNTING BOLTS (3)
2 - POWERTRAIN CONTROL MODULE (PCM)
3 - (3) 32±WAY CONNECTORS
BR/BEEMISSIONS CONTROL 25 - 1