ECO mode DODGE TRUCK 1993 Service Service Manual

•

FUEL SYSTEM
14 - 39 is not used by the PCM to calibrate air-fuel ratio
during this mode of operation,
• The up-shift indicator light is illuminated (manual
transmission only).
ENGINE
START-UP
MODE
This is an Open Loop mode. The following actions
occur when the starter motor is engaged.
The powertrain control module (PCM) receives in­
puts from:
• Battery voltage
• Engine coolant temperature sensor • Crankshaft position sensor
• Intake manifold charge air temperature sensor • Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Starter motor relay • Camshaft position sensor signal The PCM monitors the crankshaft position sensor.
If the PCM does not receive a crankshaft position sensor signal within 3 seconds of cranking the en­

gine,
it will shut down the fuel injection system.
The fuel pump is activated by the PCM through
the fuel pump relay.
Voltage is applied to the fuel injectors with the
PCM. The PCM will then control the injection se­ quence and injector pulse width by turning the
ground circuit to each individual injector on and off.
The PCM determines the proper ignition timing ac­
cording to input received from the crankshaft posi­
tion sensor.
ENGINE
WARM-UP
MODE This is an Open Loop mode. During engine warm-

up,
the powertrain control module (PCM) receives in­
puts from:
• Battery voltage • Crankshaft position sensor
• Engine coolant temperature sensor
• Intake manifold charge air temperature sensor • Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS) • Camshaft position sensor signal (in the distributor)
• Park/Neutral switch (gear indicator signal—auto,

trans,
only)
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped) Based on these inputs the following occurs:
• Voltage is applied to the fuel injectors with the
powertrain control module (PCM). The PCM will
then control the injection sequence and injector pulse
width by turning the ground circuit to each individ­ ual injector on and off.
• The PCM adjusts engine idle speed through the
idle air control (IAC) motor and adjusts ignition tim­
ing. • The PCM operates the A/C compressor clutch
through the clutch relay. This is done if A/C has
been selected by the vehicle operator and requested by the A/C thermostat.
• If the vehicle has a manual transmission, the up­
shift light is operated by the PCM.
« When engine has reached operating temperature,
the PCM will begin monitoring 02 sensor(s) input.
The system will then leave the warm-up mode and go into closed loop operation.

IDLE
MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At idle speed, the powertrain control module (PCM) receives inputs from:
Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
• Battery voltage
• Crankshaft position sensor
• Engine coolant temperature sensor • Intake manifold charge air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal (in the distributor)
® Battery voltage
• Park/Neutral switch (gear indicator signal—Auto,

trans,
only) • Oxygen sensor
Based on these inputs, the following occurs:
• Voltage is applied to the fuel injectors with the
powertrain control module (PCM). The PCM will
then control injection sequence and injector pulse
width by turning the ground circuit to each individ­ ual injector on and off.
• The PCM monitors the 02 sensor(s) input and ad­
justs air-fuel ratio by varying injector pulse width. It also adjusts engine idle speed through the idle air
control (IAC) motor. • The PCM adjusts ignition timing by increasing and decreasing spark advance.
• The PCM operates the A/C compressor clutch
through the clutch relay. This happens if A/C has
been selected by the vehicle operator and requested
by the A/C thermostat.

CRUISE
MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At cruising speed, the power-
train control module (PCM) receives inputs from:
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
• Battery voltage • Engine coolant temperature sensor
• Crankshaft position sensor
• Intake manifold charge air temperature sensor • Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal (in the distributor)

14
- 40
FUEL
SYSTEM

• • Park/Neutral switch (gear indicator signal—auto,

trans,
only)
• Oxygen (02) sensor(s) Based on these inputs, the following occurs:
• Voltage is applied to the fuel injectors with the
PCM. The PCM will then adjust the injector pulse
width by turning the ground circuit to each individ­
ual injector on and off.
• The PCM monitors the 02 sensor(s) input and ad­
justs air-fuel ratio. It also adjusts engine idle speed through the idle air control (IAC) motor.
• The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
• The PCM operates the A/C compressor clutch
through the clutch relay. This happens if A/C has
been selected by the vehicle operator and requested
by the A/C thermostat.

ACCELERATION MODE
This is an Open Loop mode. The powertrain control
module (PCM) recognizes an abrupt increase in
throttle position or MAP pressure as a demand for
increased engine output and vehicle acceleration.
The PCM increases injector pulse width in response
to increased throttle opening.

DECELERATION MODE
When the engine is at operating temperature, this
is an Open Loop mode. During hard deceleration, the
powertrain control module (PCM) receives the follow­ ing inputs.
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
• Battery voltage
• Engine coolant temperature sensor
• Crankshaft position sensor
• Intake manifold charge air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal (in the distributor)
• Park/Neutral switch (gear indicator signal —auto,

trans,
only)
If the vehicle is under hard deceleration with the
proper rpm and closed throttle conditions, the PCM
will ignore the oxygen sensor input signal. The PCM
will enter a fuel cut-off strategy in which it will not supply battery voltage to the injectors. If a hard de­
celeration does not exist, the PCM will determine the
proper injector pulse width and continue injection.
Based on the above inputs, the PCM will adjust en­
gine idle speed through the idle air control (IAC) mo­
tor. The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
The PCM opens the ground circuit to the A/C
clutch relay to disengage the A/C compressor clutch.
This is done until the vehicle is no longer under de­
celeration (if the A/C system is operating).
WIDE OPEN
THROTTLE
MODE

This is an Open Loop mode. During wide open
throttle operation, the powertrain control module (PCM) receives the following inputs.
• Battery voltage
• Crankshaft position sensor
• Engine coolant temperature sensor
• Intake manifold charge air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS) • Camshaft position sensor signal (in the distributor) During wide open throttle conditions, the following
occurs:
• Voltage is applied to the fuel injectors with the
powertrain control module (PCM). The PCM will
then control the injection sequence and injector pulse
width by turning the ground circuit to each individ­ ual injector on and off. The PCM ignores the oxygen sensor input signal and provides a predetermined amount of additional fuel. This is done by adjusting
injector pulse width.
• The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
• The PCM opens the ground circuit to the A/C
clutch relay to disengage the A/C compressor clutch.
This will be done for approximately 15 seconds (if the air conditioning system is operating).
If the vehicle has a manual transmission, the up­
shift light is operated by the PCM.

IGNITION
SWITCH
OFF
MODE
When ignition switch is turned to OFF position,
the PCM stops operating the injectors, ignition coil,
ASD relay and fuel pump relay.

THROTTLE
BODY
Filtered air from the air cleaner enters the intake
manifold through the throttle body (Fig. 18). Fuel does not enter the intake manifold through the throt­
tle body. Fuel is sprayed into the manifold by the fuel injectors. The throttle body is mounted on the
intake manifold. It contains an air control passage (Fig. 19) controlled by an idle air control (IAC) mo­
tor. The air control passage is used to supply air for idle conditions. A throttle valve (plate) is used to supply air for above idle conditions. The throttle position sensor (TPS), idle air control
(IAC) motor and manifold absolute pressure sensor
(MAP) are attached to the throttle body. The acceler­
ator pedal cable, speed control cable and transmis­
sion control cable (when equipped) are connected to
the throttle arm. A (factory adjusted) set screw is used to mechani­
cally limit the position of the throttle body throttle
plate. Never attempt to adjust the engine idle speed using this screw. All idle speed functions are
controlled by the PCM.

•

FUEL SYSTEM
14 - 59
fill
DHADn
HIAf5MflCTipQ
/f|Rn

The powertrain control module (PCM) has been
programmed to monitor many different circuits of the
fuel injection system. If a problem is sensed in a monitored circuit often enough to indicate an actual
problem, a diagnostic trouble code (DTC) is stored.
The DTC will be stored in the PCM memory for eventual display to the service technician. If the
problem is repaired or ceases to exist, the PCM can­ cels the DTC after 51 engine starts.
Certain criteria must be met for a diagnostic trou­
ble code (DTC) to be entered into PCM memory. The criteria may be a specific range of engine rpm, en­
gine temperature and/or input voltage to the PCM.
It is possible that a DTC for a monitored circuit
may not be entered into memory even though a mal­
function has occurred. This may happen because one
of the DTC criteria for the circuit has not been met. Example: assume that one of the criteria for the
MAP sensor circuit is that the engine must be oper­ ating between 750 and 2000 rpm to be monitored for
a DTC. If the MAP sensor output circuit shorts to
ground when the engine rpm is above 2400 rpm, a 0
volt input will be seen by the PCM. A DTC will not
be entered into memory because the condition does not occur within the specified rpm range.
A DTC indicates that the powertrain control mod­
ule (PCM) has recognized an abnormal signal in a
circuit or the system. A DTC may indicate the result
of a failure, but never identify the failed component
directly.
There are several operating conditions that the
PCM does not monitor and set a DTC for. Refer to
the following Monitored Circuits and Non-Monitored Circuits in this section.

MONITORED
CIRCUITS
The powertrain control module (PCM) can detect
certain problems in the fuel injection system.
Open or Shorted Circuit - The PCM can deter­
mine if sensor output (which is the input to PCM) is
within proper range. It also determines if the circuit is open or shorted.
Output Device Current Flow - The PCM senses
whether the output devices are hooked up.
If there is a problem with the circuit, the PCM
senses whether the circuit is open, shorted to ground
(-), or shorted to
(
+
)
voltage.
Oxygen Sensor - The PCM can determine if the
oxygen sensor is switching between rich and lean.
This is, once the system has entered Closed Loop. Re­ fer to Open Loop/Closed Loop Modes Of Operation in
the Component Description/System Operation section
for an explanation of Closed (or Open) Loop opera­ tion.
NON-MONITORED CIRCUITS

The PCM does not monitor the following circuits,
systems or conditions that could have malfunctions
that result in driveability problems. A diagnostic trouble code (DTC) may not be displayed for these
conditions.
Fuel Pressure: Fuel pressure is controlled by the
vacuum assisted fuel pressure regulator. The PCM
cannot detect a clogged fuel pump inlet filter, clogged
in-line fuel filter, or a pinched fuel supply or return

line.
However, these could result in a rich or lean
condition causing an oxygen sensor DTC to be stored in the PCM.
Secondary Ignition Circuit: The PCM cannot de­
tect an inoperative ignition coil, fouled or worn spark

plugs,
ignition cross firing, or open circuited spark
plug cables.
Engine Timing: The PCM cannot detect an incor­
rectly indexed timing chain, camshaft sprocket or crankshaft sprocket. The PCM also cannot detect an
incorrectly indexed distributor. However, these could
result in a rich or lean condition causing an oxygen
sensor DTC to be stored in the PCM.
Cylinder Compression: The PCM cannot detect
uneven, low, or high engine cylinder compression.
Exhaust System: The PCM cannot detect
a

plugged, restricted or leaking exhaust system.
Fuel Injector Malfunctions: The PCM cannot de­
termine if the fuel injector is clogged, or the wrong injector is installed. However, these could result in a
rich or lean condition causing an oxygen sensor DTC
to be stored in the PCM.
Excessive Oil Consumption: Although the PCM
monitors exhaust stream oxygen content through ox­
ygen sensor (closed loop), it cannot determine exces­ sive oil consumption.
Throttle Body Air Flow: The PCM cannot detect
a clogged or restricted air cleaner inlet or air filter
element.
Evaporative System: The PCM will not detect a
restricted, plugged or loaded EVAP canister. Vacuum Assist: Leaks or restrictions in the vac­
uum circuits of vacuum assisted engine control sys­
tem devices are not monitored by the PCM. However, a vacuum leak at the MAP sensor will be monitored
and a diagnostic trouble code (DTC) will be gener­
ated by the PCM.
Powertrain Control Module (PCM) System
Ground: The PCM cannot determine a poor system
ground. However, a DTC may be generated as a re­
sult of this condition.
Powertrain Control Module (PCM) Connector
Engagement: The PCM cannot determine spread or
damaged connector pins. However, a DTC may be generated as a result of this condition.

14 - 82
FUEL 'SYSTEM
—. — ~—— — «

INTAKE HEATER CYCLE CHART

Intake
featperafwre
Preheat
Cycle
Time

Ignition
l£ey ON

Engine
Not
Running
Pestheat
Cycle

Ignition
Key ON
Snglne Running

Above
15
°C
(59
°F)
0 Seconds
No

-8°C(18°F)to
15°C (59
°F)
10
Seconds

Yes

-17°C(1
°F)
-9
°C(]6°F)
15
Seconds
Yes

«2d°C(-15°F)
to-18°C(0
°F) 17.5
Seconds
Yes

Below-26
°C (-15
*F)
20 Seconds

Yes

J9114-239
AUTO SHUT DOWN (ASD) RELAY-PCM OUTPUT
The ASD relay is located in the engine compart­
ment (Fig. 14).
TORQUE CONVERTER
CLUTCH RELAY A/C CLUTCH RELAY STARTER RELAY
AUTO SHUTDOWN RELAY FUEL PUMP RELAY DATA LINK
CONNECTOR
POWERTRAIN

CONTROL MODULE
J9314-164

Fig.
14 Relay Location—Typical The ASD relay supplies battery voltage to the gen­
erator field winding to provide regulation of the
charging system. The ground circuit for the ASD re­
lay is controlled by the PCM. The PCM operates the
relay by switching the ground circuit on and off.

MALFUNCTION INDICATOR LAMP-PCM OUTPUT
The malfunction indicator lamp (formerly referred
to as the check engine lamp) illuminates at the bot­
tom of the instrument panel each time the ignition
key is turned on. It will stay on for three seconds as
a bulb test. If the powertrain control module (PCM) receives an
incorrect signal, or no signal from certain sensors or emission related systems, the lamp is turned on. This
is a warning that the PCM has recorded a system or
sensor malfunction. In some cases, when a problem is
declared, the PCM will go into a limp-in mode. This is an attempt to keep the system operating. It signals
an immediate need for service.
The lamp can also be used to display a diagnostic
trouble code (DTC). Cycle the ignition switch
On-Off-
On-Off-On within three seconds and any codes stored
in the PCM memory will be displayed. This is done
in a series of flashes representing digits. Refer to On-
Board Diagnostics in the General Diagnosis section
of this group for more information.

OVERDRIVE
INDICATOR LAMP-PCM OUTPUT
Indicates the state of the overdrive defeat switch
on the instrument panel.

OVERDRIVE
S0LEN0ID-PCM OUTPUT
The overdrive solenoid is used on vehicles that
have an automatic transmission. The solenoid is op­ erated by the PCM. It controls shifting in and out of
overdrive through the overdrive solenoid. Refer to Group 21 for overdrive solenoid service.

SCI
TRANSMIT—PCM OUTPUT
SCI Transmit is the serial data communication
transmit circuit for the DRB II scan tool. The PCM
transmits data to the DRB II through the SCI Trans­
mit circuit.

SPEED
C0NTR0L-PCM OUTPUT
The speed control vacuum and vent solenoids are
operated by the PCM. The vacuum solenoid main­
tains vacuum at a required pressure to resume, set or accelerate the speed control system. The vent so­
lenoid allows vacuum to bleed off during decelera­
tion, when the brakes are applied, or the
transmission is shifted into park or neutral.

TACHOMETER-PCM
OUTPUT
This output generates the necessary signal needed
to operate a dealer installed tachometer (if equipped).
The input for this signal is from the engine speed sensor.

WAIT-TO-START LAMP-PCM OUTPUT
The wait-to-start lamp is turned on and off by the
PCM based on the charge air temperature sensor in­
put. The light is turned on when the ignition is first ac­
tivated. It will remain on for two seconds as a bulb
test. If the PCM reads intake manifold air tempera­
ture below 15°C (59°F), it will turn the wait-to-start light on for the intake heater preheat cycle. The
light stays on until the preheat cycle is over. The wait-to-start light will flash on and off if the
charge air temperature sensor input to the PCM is

•
TRANSMISSION
AND
TRANSFER
CASE
21 - 1

CONTENTS

page

AUTOMATIC
TRANSMISSI0N-32RH/36RH/
37RH/42RH/46RH
73

G360
MANUAL
TRANSMISSION
46

6360
TRANSMISSION
OVERHAUL
..........
53
NP2Q5
TRANSFER
CASE
................
342
page

NP241
TRANSFER
CASE
350

NV4500 MANUAL
TRANSMISSION
1

NV4500
TRANSMISSION
OVERHAUL
.........
6

TRANSMISSION/TRANSFER
CASE

SPECIFICATIONS
.....................
364

NV4300
MANUAL TRANSMISSION
INDEX

page
Gear Ratios
1

General
Information
1
Recommended
Lubricant—Capacity—Fill
Level
... 1

Shift
Pattern
1

Transmission Diagnosis
2
page
Transmission
Identification
1

Transmission
Installation—2-Wheel
Drive
4

Transmission
Installation—4-Wheel
Drive
........
5

Transmission
Removal—2-Wheel
Drive
3

Transmission
Removal—4-Wheel
Drive
4

GENERAL
INFORMATION The NV4500
is a
five-speed, constant mesh manual
transmission (Fig.
1). All
gear ranges including
re­

verse
are
synchronized. Fifth gear
is an
overdrive
range with
a
ratio
of
0.74:1.
The transmission has
a

cast iron gear case and aluminum shift cover. The NV4500
is a
top loader style transmission. The
shift lever
is
located
in the
shift cover and operates
the shift forks and rails directly. The shift forks and
rails
are all
located within
the
aluminum cover
which
is
bolted
to
the top
of
the gear case.
A reverse gear inhibitor mechanism prevents
re­

verse gear engagement when shifting into forward
gear ranges. The inhibitor mechanism
is
located
in

the shift cover.
Tapered roller bearings support
the
drive gear,
mainshaft
and
countershaft
in the
gear case. Pilot
roller bearings
in
the drive gear hub support the for­
ward end
of
the mainshaft. The mainshaft gears
are
all supported
on
caged type roller bearings. Drive
gear thrust reaction
is
controlled
by a
needle type
thrust bearing. The bearing
is
located
at
the forward
end
of
the mainshaft.

TRANSMISSION
IDENTIFICATION The NV4500 transmission identification
tag is at­

tached
to
the driver side PTO cover (Fig.
2).
The
tag
provides
the
transmission model number,
build date and part number.
Be
sure
to
reinstall
the
I.D.
tag if
removed during service. The information
on the tag
is
essential
to
correct parts ordering.

RECOMMENDED
LUBRICANT-CAPACITY-FILL

LEVEL
Recommended lubricant
for
the NV4500
is
Castrol
Syntorq. This
is a
SAE 75W-90 synthetic gear lubri­
cant with
an
API grade rating
of
GL
4.
Syntorq
is

the only lubricant recommended
for
use
in
NV4500 transmissions. Dry fill lubricant capacity
is
approximately 3.78
li­

ters
(8
pints). Correct lubricant fill level
is to
the bottom edge
of

the fill plug hole (Fig. 3). Check fill level only when
the transmission
is
level.

GEAR
RATIOS
NV4500 gear ratios are:
First gear:
5.61:1
Second gear: 3.04:1
Third gear:
1.67:1
Fourth gear:
1.00:1

Fifth gear: 0.74:1
Reverse gear:
5.61:1

SHIFT
PATTERN
The NV4500 shift pattern
is in a
modified
H
pat­
tern (Fig. 4). Overdrive fifth and reverse gears are
in
line and outboard of the first through fourth gear po­
sitions.

TRANSMISSION
AND
TRANSFER
CASE

•

G360
TRANSMISSION OVERHAUL
21 - 53
G360
TRANSMISSION
OVERHAUL

INDEX

page

Transmission
Assembly
and
Adjustment
.......
63

Transmission
Cleaning
and
Inspection
59

TRANSMISSION
DISASSEMBLY

SHIFT COVER REMOVAL (1) Shift transmission into neutral.
(2) Remove shift cover bolts.
(3) Loosen shift cover with
two pry
tools. Insert
tools
in
cover slots
and pry
cover
off
alignment dow­ els
(Fig. 1). It is
important
to
remove
the
cover evenly
to
avoid damage.
Do not pry one
side
loose then
the
other. This practice could damage the forks
and
cover.

SHIFT

COVER

Fig.
1
Loosening
Shift
Cover

(4) Remove shift cover assembly
(Fig. 2).
Discard
old shift cover gasket. Note that
a
gasket
was not

used
on
early production transmissions.
It is

recommended that
a
gasket
be
used when shift
cover
is
installed after overhaul. (5)
Set
shift cover assembly aside
for
inspection.

REARING
RETAINER
AND
SHAFT BEARING

RACE
REMOVAL (1) Remove front bearing retainer bolts
and re­

move retainer
(Fig. 3). Tap
retainer with rubber mal­ let
to
loosen
it if
necessary.
(2)
On
2-wheel drive models, remove rear bearing
retainer
as
follows
(Fig. 4):
(a) Remove
nut
attaching yoke
to
output.
Torque
on nut is
quite high. Best
way to re­

move
nut is
with 350-400
ft. lb.
rated high
ca­

pacity impact wrench.
(b) Remove yoke from output shaft splines.
page

Transmission
Disassembly
53

Fig.
2
Shift
Cover
Removal/Installation

CHANNELS
(4)
J9321-268
Fig.
3
Front Bearing Retainer
Removal

(c) Remove bolts attaching rear bearing retainer
to gear case
and
remove retainer.
Use
rubber mal­ let
to
loosen retainer
if
necessary.
(d) Remove speedometer gear
and
spacers from
output shaft.
(e) Remove preload shims from rear retainer,
or

bearings.
(f) Remove yoke seal from retainer with suitable
pry tool.
Do not
damage retainer surface while
re­
moving seal.
(3)
On
4-wheel drive transmission, remove rear
bearing retainer bolts
and
remove retainer from gear case
(Fig. 5).

•

AUTOMATIC
TRANSMISSION—32RH/36RH/37RH/42RH/46RH
21 - 81
TORQUE
CONVERTER

A three element torque converter
is
used
for all ap­

plications.
The
converter consists
of the
impeller,
sta-

tor
and
turbine.
The
converter also contains
an
overrunning clutch
and a
modulated converter clutch
mechanism.
The converter used with
1993,
42RH transmissions
is
new. The
converter
hub was
changed
to
accept
the

new style drive flats
on the oil
pump inner gear.
The

new style converter
is not
interchangeable with pre­
vious designs.
The converter modulated clutch consists
of a
slid­
ing clutch piston, clutch springs
and the
clutch disc
friction material.
The
clutch provides optimum
torque transfer
and
economy when engaged.
The clutch disc
is
attached
to the
converter front
cover.
The
clutch piston
and
clutch springs
are at­

tached
to the
turbine
hub. The
springs dampen
en­
gine firing impulses
and
loads during
the
initial
phase
of
converter clutch engagement.
Clutch engagement
is
controlled
by the
converter
clutch valve
and
solenoid. Both
are
located
on the

transmission valve body. Clutch engagement occurs in drive range
at
speeds above approximately 30-35
mph.
The clutch provides reduced engine speed
and

greater fuel economy when engaged. Clutch engage­
ment also provides reduced transmission fluid tem­
peratures.

COMPONENTS
UNIQUE
TO
DIESEL VERSION
OF

46RH

Planetary
Gears
The transmission
and
overdrive planetary gear car­
riers
in the
diesel version
of the
46RH
are
heavy duty components.
The
transmission planetary carri­ers have four pinion gears.
The
carrier
in the
over­
drive compounder
has
five pinion gears.
The
heavy
duty planetary units
are
unique
to the
diesel 46RH.

Clutch
Packs
Clutch packs used
in the
diesel version
of the

46RH contain
the
following number
of
discs
and

plates:

• transmission front/rear clutch
has 4
discs
and 5

steel plates
• overdrive clutch
has 5
discs
and 6
steel plates
• overdrive direct clutch
has 8
discs
and 9
steel
plates

Governor
Weight
Assembly
The governor weight assembly
in the
diesel 46RH
is made
of
alloyed brass.
The
diesel weight assembly
is easily identified
by the
distinctive gold color
of the
alloyed material.
The
heavier weight assembly pro­
vides
the
shift points needed
to
offset lower operating speeds
of a
diesel engine. The alloyed weight assembly
is
unique
to the
diesel
46RH.
It is not
interchangeable with
the
weight
as­
semblies used
in gas
engine versions.

Diesel
Thermo
Switch
Fourth gear operation
in the
diesel 46RH
is
also
controlled
by two
temperature sensitive thermo- switches.
The first thermo-switch
is the
engine coolant tem­
perature switch. This switch prevents overdrive fourth gear operation when engine coolant tempera­
ture
is
below approximately
65° F.

The second thermo-switch directly monitors trans­
mission fluid temperature.
The
switch will either
downshift
the
transmission
to
third gear,
or
prevent a
3-4
upshift when fluid temperature exceeds
270-275°
F.

The fluid temperature switch
is
located
in a
boss
built into
the
cooler outlet line.
The
boss
and
switch are located approximately
2-3
inches from
the
outlet
line fitting
in the
transmission case.
The engine coolant
and
fluid temperature switches
are
in
circuit with
the
overdrive control switch
in the

instrument panel.

GEAR RATIOS
42RH forward gear ratios
are:

First gear
=
2.74:1
Second gear
= 1.54:1

Third gear
= 1.00:1
Fourth gear
=
0.69:1.
46RH forward gear ratios
are:

First gear
=
2.45:1 Second gear
= 1.45:1

Third gear
= 1.00:1
Fourth gear
=
0.69:1.

RECOMMENDED
FLUID
The recommended
and
preferred fluid
for
42RH/
46RH transmissions
is
Mopar
ATF
Plus, type
7176.

Use Mopar Dexron
II
only when
ATF
Plus
is not

readily available.

TRANSMISSION
IDENTIFICATION
The transmission part
and
identification numbers
and codes
are
stamped
on the
left side
of the
case
just above
the oil pan
gasket surface
(Fig. 3).
The first letter/number group
is the
assembly part
number.
The
next number group
the
transmission
build date.
The
last number group
is the
transmis­ sion serial number. Refer
to
this information when
ordering replacement parts.

FOURTH
GEAR OVERDRIVE COMPONENTS
42RH/46RH models have three transmission shafts.
An intermediate shaft
is
positioned between
the in­

put
and
output shafts.
The
output shaft
is in the

•

TRANSMISSION
OVERHAUL-46RH
21 - 295 are installed. Install same number of discs and
plates as removed during disassembly. Some
models require 3 plates and discs. Others re­ quire 4 plates and discs.
(10) Install reaction plate and waved snap ring.
(11) Check clutch pack clearance with feeler gauge
as follows (Fig. 65):
• On 3 disc clutch, clearance between waved spring
and pressure plate should 1.78 - 3.28 mm (0.070 -
0.129 in.).
• On 4 disc clutch, clearance between waved spring
and pressure plate should be 2.08 to 3.83 mm (0.082
to 0.151 in.). • If clearance Is Incorrect, clutch plates, clutch

discs,
snap ring and pressure plate will have to
be changed. Clutch pack waved snap ring is not select fit.

FEELER
GAUGE
RH288

Fig.
65
Measuring
Front
Clutch
Pack
Clearance

REAR
CLUTCH OVERHAUL

REAR
CLUTCH DISASSEMBLY
(FIG. 66) (1) Remove clutch pack select fit snap ring.
(2) Remove reaction plate and remove clutch plates
and discs.
(3) Remove pressure plate, wave spring, spacer
ring and piston spring from clutch retainer.
(4) Remove clutch piston from piston retainer with
a twisting motion. (5) Remove input shaft thrust washer, if washer
remained in piston retainer hub during removal.
(6) Remove seals from clutch piston. Discard seals
after removal.
REAR
CLUTCH INSPECTION

Clean the clutch components with solvent and dry
them with compressed air. Check condition of the input shaft seal rings. It is
not necessary to remove or replace rings unless they
are broken, cracked, or no longer securely hooked to­ gether.
Inspect the input shaft splines and machined sur­

faces.
Very minor nicks or scratches can be smoothed off with crocus cloth, replace the shaft if the splines
are damaged, or any of the machined surfaces are se­
verely scored.
Replace the clutch discs if warped, worn, scored,
burned/charred, the lugs are damaged, or if the fac­ ing is flaking off.
Replace the steel plates and the pressure plate if
heavily scored, warped, or broken. Be sure the driv­ ing lugs on the discs and plates are also in good con­
dition. The lugs must not be bent, cracked or
damaged in any way.
Replace the piston spring and wave spring if either
part is distorted, warped or broken.
Check the lug grooves in the clutch retainer. The
steel plates should slide freely in the slots. Replace
the retainer if the grooves are worn or damaged.
Also check action of the retainer check ball. The ball must move freely and not stick.
Inspect the piston and retainer seal surfaces for
nicks or scratches. Minor scratches can be removed
with crocus cloth. However, replace the piston and/or
retainer if the seal surfaces are seriously damaged.
Check thrust washer condition. Washer thickness
should be 1.55 to 1.60 mm (0.061 to 0.063 in.). Re­
place the washer if worn or damaged.
Check condition of the two seal rings on the input
shaft and the single seal ring on the piston retainer

hub.
Replace the seal rings only if severely worn, cracked, or if they can no longer be hooked together.

INPUT SHAFT REPLACEMENT
If the input shaft must be replaced, first remove
the retaining ring that secures the shaft in the pis­
ton retainer hub. Then press the old shaft out of the retainer with a shop press.
Lubricate the splines of the new shaft with petro­
leum jelly or ATF Plus. Then align the shaft in the
piston retainer and carefully press it into place. Do not allow the shaft to become cocked during installa­
tion. The retainer can be cracked if misalignment oc­
curs.

Install the shaft retaining ring after pressing the

.
shaft into place. Be sure the ring is fully seated be­ fore proceeding with clutch assembly.

21
- 342
NP205 TRANSFER CASE

•
NP205
TRANSFER CASE

INDEX
page
General
Information
342
Recommended Lubricants
342

Service Diagnosis
342

Shift
Linkage
Adjustment
344

Speedometer Service
345

GENERAL
INFORMATION

The NP205 transfer case
is a
heavy duty, part-time
unit with constant mesh, helical gears.
The
gears
are

mounted
in a
one-piece, cast iron gear case. The NP205 provides four operating ranges which

are:
4-wheel drive high, neutral, 2-wheel drive high
and 4-wheel drive
low (Fig. 1).
The transfer case gears rotate
on
shafts supported
by ball
and
roller bearings. Sliding clutch sleeves and shift forks
are
used
to
engage
or
disengage
the

drive gears. The NP205 geartrain provides high
and low
ranges
in 4-wheel drive mode.
The
high range
has a 1:1 ra­

tio
for
normal operation
and a low
range with
a re­
duction ratio
of 1.96:1 for
extra pulling power
in off

road situations. In two-wheel drive range,
the
transfer case front
output shaft drive gear
is
disengaged. Torque
is not

transmitted
to the
front propeller shaft.
Fig.
1
NP205 Transfer
case

RECOMMENDED
LUBRICANTS
Recommended lubricants
for the
NP205 transfer
case include multi-purpose gear lubricants
and
single
weight engine oils. Engine
oil
should
be API
classification SF/CC
or

SF/CD.
Use SAE 30 at
ambient temperatures below
0°
C
(
+
32°
F) and SAE 50 at
ambient temperatures
above this point.
page
Transfer
Case
Assembly
348

Transfer
Case
Disassembly
..........
345

Transfer
Case
Identification
342

Transfer
Case
Installation
345

Transfer
Case
Removal
345

SAE multi-purpose gear lubricants with
an API

grade rating
of GL 5 are
recommended
for
severe
duty operation.
SAE
grades
80,
75W-90,
90,
80W-90, 140
and
80W-140
are all
acceptable.
Use
SAE 80 or
75W-90 when ambient tempera­
tures
are
below
-23° C (-10° F). Use SAE 90, or
80W-90 when ambient temperature
is
above
the

stated range.
SAE
140, or
80W-140
can be
used when severe ser­
vice
is
anticipated,
or
when ambient temperatures are expected
to
exceed +32°
C (90° F).

Transfer Case Shift Linkage Lubrication
The transfer case shift linkage pivot
and
contact
surfaces should
be
lubricated with engine
oil at
rec­
ommended intervals. Lubrication frequency
for the

linkage
is
described
in
Lubrication
And
Maintenance Group
O.

TRANSFER CASE
IDENTIFICATION
The NP205 identification
tag is
attached
to the

PTO cover
on the
driver side
of the
transfer case.
The
tag
contains transfer case manufacturing
and as­
sembly part numbers. Refer
to
this information when
ordering service replacement parts.

SERVICE
DIAGNOSIS
The most frequent causes
of
transfer case malfunc­
tions
are:
• improper operation
• insufficient lubricant
• non-recommended lubricant
• misadjusted shift linkage
• improper assembly after repair. The general problems
and
causes
of
transfer case
malfunctions
are
outlined below.

LOW LUBRICANT LEVEL
A
low
lubricant level
is
usually
the
result
of
loose
components, leakage,
or
improper checking and/or
filling techniques. Lubricant leaks
can
occur
at the
shaft seals, case
vent,
or
gasket joints. Most leaks will
be
evident
by

the presence
of
lubricant around
the
leakage point. However,
be
sure
the
leakage
is
actually from
a

transfer case component.

21 - 350 NP241
TRANSFER CASE

• NP241 TRANSFER CASE

INDEl

page

Checking
Fluid
Level
351

Component Cleaning
and
Inspection
359
Fluid
Drain/Refill
351

General
Information
350

Recommended
Lubricant
.................. 350

Service
Diagnosis
....................... 350

Shift
Linkage
Adjustment
354

Speedometer Adapter/Distance
Sensor
Service
. 352
page

Speedometer Gear, Shaft
Seal,
Bearing
and
Retainer
Service
352

Transfer
Case
Assembly
.................. 361

Transfer
Case
Bearing Replacement
......... 360
Transfer
Case
Disassembly
................ 356

Transfer
Case
Identification ................ 350

Transfer
Case
Installation
................. 356

Transfer
Case
Removal
356

GENERAL
INFORMATION
The NP241 is a part-time transfer case with a low-
range gear system. It has three operating ranges
plus a Neutral position. The low range system pro­ vides a gear reduction ratio for increased low speed
torque capability. NP241 operating ranges are: 2-high, 4-high and 4-low. The NP241 has an aluminum, two-piece gear case.
Drive sprockets and an interconnecting drive chain are used to transmit engine torque to the propeller

shafts.
Four-wheel high and low ranges are undifferenti­
ated. The transfer case is not designed for continuous
operation in 4WD range on hard or paved surfaces.
Four wheel drive ranges are recommended for off
road operation, or on snow covered or similar low
traction surfaces. A front axle disconnect system is used to achieve
two-wheel drive mode. The axle disconnect vacuum motor is actuated by a vacuum switch on the transfer

case.
The switch is operated by the transfer case
range rod. Two-wheel drive range is used for on road, high­
way operation. The four-wheel drive ranges are for off road operation or when the vehicle is driven on
paved road surfaces covered by snow, ice or similar low traction elements.

TRANSFER CASE
IDENTIFICATION
An identification tag (Fig, 1) is attached to the rear
case of each NP241 transfer case. The tag provides
the transfer case model number, assembly number, serial number, and low range ratio. The transfer case serial number also represents the
date of build. For example, a serial number of 9-10-92 would represent September 10, 1992. Transfer case operating ranges are selected with a
floor-mounted shift lever. The shift lever is connected
to the transfer case range lever by an adjustable linkage rod (Fig. 2). A straight line shift pattern is
used. Range positions are marked on the gearshift le­
ver knob.
Fig.
1 NP 241 Transfer
Case

A synchronizer assembly in the transfer case al­
lows the unit to be shifted between 2H and 4H
ranges while the vehicle is in motion. The vehicle should be stopped before shifting into 4L range.

RECOMMENDED
LUBRICANT
Recommended lubricant for the NP241 is Mopar
ATF Plus, type 7176, or Dexron II™ automatic trans­
mission fluid. Use either fluid for topping off the
level, or refilling after service, or normal fluid
changes. Do not use anti-friction additives or similar prod­
ucts in the NP241 transfer case. Use the recom­
mended lubricant only. NP241 transfer case lubricant should be changed
at the intervals specified in the Maintenance Sched­
ule or after service repairs.

SERVICE
DIAGNOSIS
Before attempting to repair a suspected transfer
case malfunction, check all other driveline compo­
nents beforehand. The actual cause of a problem may be related to
such items as: front hubs, axles, propeller shafts,
wheels and tires, transmission, or clutch instead. If all other driveline components are in good condition