ECO mode DODGE RAM 2001 Service Manual PDF

NOTE: If the PDC is being replaced with a new unit,
be certain to transfer each of the blade-type fuses,
cartridge fuses and relays from the faulty PDC to
the proper cavities of the replacement PDC. Refer
to Power Distribution in the index of this service
manual for the location of complete PDC circuit dia-
grams and cavity assignments.(1) Position the PDC and the headlamp and dash
wire harness unit in the engine compartment.
(2) Install and tighten the two screws that secure
the PDC housing to the left front fender inner shield.
Tighten the screws to 8.4 N´m (75 in. lbs.).
(3) Install and tighten the screw that secures the
PDC housing to the left front fender wheel housing.
Tighten the screw to 2.2 N´m (20 in. lbs.).
(4) Install the eyelet of the battery positive cable
PDC take out onto the forward B(+) terminal stud in
the PDC.
(5) Install and tighten the nut that secures the
eyelet of the battery positive cable PDC take out to
the forward B(+) terminal stud in the PDC. Tighten
the nut to 8.4 N´m (75 in. lbs.).
(6) Install the eyelet of the battery negative cable
generator output take out onto the rearward B(+) ter-
minal stud in the PDC.
(7) Install and tighten the nut that secures the
eyelet of the battery negative cable generator output
take out to the rearward B(+) terminal stud in the
PDC. Tighten the nut to 75 in. lbs.
(8) Reconnect the engine wire harness in-line con-
nector to the PDC.
(9) Install and tighten the screw that secures the
engine wire harness in-line connector to the PDC.
Tighten the screw until a distinct audible click is
heard.
(10) Install and latch the cover onto the PDC.
(11) Engage each of the retainers that secure the
headlamp and dash wire harness to the vehicle body
and chassis components. Refer toConnector Loca-
tionsin the index of this service manual for the loca-
tion of more information on the headlamp and dash
wire harness retainer locations.
(12) Install all of the fasteners that secure each of
the headlamp and dash wire harness ground eyelets
to the vehicle body and chassis components. Refer to
Connector Locationsin the index of this service
manual for the location of more information on the
ground eyelet locations.
(13) Reconnect each of the headlamp and dash
wire harness connectors. Refer toConnector Loca-
tionsin the index of this service manual for the loca-
tion of more information on the headlamp and dash
wire harness connector locations.
(14) Reconnect the battery negative cable.POWER OUTLET
DESCRIPTION
An accessory power outlet is standard equipment
on this model. The power outlet is installed in the
instrument panel below the cigar lighter and next to
the ash receiver, which is located near the center of
Fig. 9 Battery and Generator Connections to PDC
1 - NUTS
2 - BATTERY POSITIVE CABLE
3 - BATTERY NEGATIVE CABLE
4 - POWER DISTRIBUTION CENTER
5 - CABLE EYELETS
Fig. 10 Power Distribution Center
1 - FENDER INNER SHIELD
2 - INNER WHEEL HOUSE
3 - SCREW
4 - SCREW
5 - POWER DISTRIBUTION CENTER
BR/BE8W-97 POWER DISTRIBUTION 8W - 97 - 9
POWER DISTRIBUTION CENTER (Continued)

(9) Remove viscous fan/drive assembly (Refer to 7 -
COOLING/ENGINE/RADIATOR FAN - REMOVAL).
Remove the cooling fan and shroud together.
(10) Disconnect the coolant recovery bottle hose
from the radiator filler neck and remove bottle from
fan shroud (Fig. 2).
(11) Disconnect heater core supply and return
hoses from the cylinder head fitting and coolant pipe.
(12) Raise vehicle on hoist.
(13) Remove transmission and transfer case (if
equipped.).
(14) Disconnect exhaust pipe from turbocharger
extension pipe (Fig. 3).
(15) Remove starter motor (Refer to 8 - ELECTRI-
CAL/STARTING/STARTER MOTOR - REMOVAL).
(16) Disconnect A/C suction/discharge hose from
the rear of the A/C compressor.
(17) Lower vehicle.
(18) Disconnect lower radiator hose from radiator
outlet.
(19)Automatic Transmission models:Discon-
nect transmission oil cooler lines from radiator using
special tool #6931.
(20) Remove radiator (Refer to 7 - COOLING/EN-
GINE/RADIATOR - REMOVAL).
(21) Remove upper radiator support panel.
(22)
Remove front bumper (Refer to 13 - FRAMES &
BUMPERS/BUMPERS/FRONT BUMPER - REMOVAL).
(23) If A/C equipped, disconnect A/C condenser
refrigerant lines.
(24) Disconnect charge air cooler piping.
(25) Remove the two charge air cooler mounting
bolts.
(26) Remove charge air cooler (and A/C condenser
if equipped) from vehicle.
(27) Disconnect engine block heater connector.
(28) Disconnect A/C compressor electrical connec-
tors.
(29) Remove the passenger battery ground cable
from the engine block.
(30) Disconnect power steering pump pressure and
return lines.
(31) Remove accelerator linkage cover.
(32) Leaving all cables attached, remove accelera-
tor pedal position sensor assy. (APPS) (Fig. 4) from
cylinder head bracket and secure out of the way.
(33) Disconnect APPS connector (Fig. 5).
(34) Disconnect vacuum pump supply hose (Fig. 6).
(35) Disconnect the engine harness and ground
cable from the PDC.
(36) Disconnect the fuel supply and return hoses
(Fig. 7).
(37) Remove the cylinder head cover (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - REMOVAL).
(38) Remove the #5 and #6 cylinder intake and
exhaust rocker arms and pedestals (Fig. 8). Note the
original location for re-assembly.
(39) Loosen but do not remove engine mount
through bolts and nuts.
(40) Attach chain accross engine lift brackets.
(41)
Lift engine up and out of engine compartment.
(42) Install engine to suitable engine stand.
Fig. 2 Coolant Recovery Bottle
1 - T-SLOTS
2 - ALIGNMENT PIN
3 - FAN SHROUD
4 - COOLANT RESERVE/OVERFLOW TANK
Fig. 3 Exhaust Pipe Connection at Turbocharger
1 - EXHAUST PIPE
2 - TURBOCHARGER EXHAUST PIPE
BR/BEENGINE 5.9L DIESEL 9 - 239
ENGINE 5.9L DIESEL (Continued)

Inspect the tappet bores for scoring or excessive
wear 16.000 mm min - 16.055 mm max ( .63 in. min
- .6321 in. max ) (Fig. 81). If out of limits, replace the
cylinder block.
CAMSHAFT & BEARINGS (IN
BLOCK)
REMOVALÐCAMSHAFT BEARINGS
NOTE: Measure the diameter of each bore. (The
limit for the bushing in the No.1 bore is the same as
for the other bores without bushings). The limit of
the inside diameter is 54.089 min. - 54.164 max. mm
(2.1295 min. - 2.1325 max. inch). If the camshaft
bore for the first cam bushing is worn beyond the
limit, install a new service bushing. Inspect the rest
of the camshaft bores for damage or excessive
wear.If the bores without a bushing are worn
beyond the limit, the engine must be removed for
machining and installation of service bushings. If
badly worn, replace the cylinder block.
(1) Remove the camshaft (Refer to 9 - ENGINE/
ENGINE BLOCK/CAMSHAFT & BEARINGS (IN
BLOCK) - REMOVAL).
(2) Remove the bushing from the No.1 bore, using
a universal cam bushing tool.
(3) Mark the cylinder block so you can align the oil
hole in the cylinder block with the oil hole in the
bushing.
REMOVALÐCAMSHAFT
(1) Disconnect both battery negative cables.
(2) Recover A/C refrigerant (if A/C equipped) (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMB-
ING - STANDARD PROCEDURE).
(3) Raise vehicle on hoist.
(4) Drain engine coolant into container suitable for
re-use (Refer to 7 - COOLING - STANDARD PROCE-
DURE).
(5) Lower vehicle.
(6) Remove radiator upper hose.
(7) Remove viscous fan/drive assembly and fan
shroud (Refer to 7 - COOLING/ENGINE/RADIATOR
FAN - REMOVAL).
(8) Disconnect the coolant recovery bottle hose
from the radiator filler neck.
(9) Disconnect lower radiator hose from radiator
outlet.
(10)Automatic Transmission models:Discon-
nect transmission oil cooler lines from radiator using
Special Tool 6931 (unless equipped with finger-re-
lease disconnect).
(11) Remove radiator mounting screws and lift
radiator out of engine compartment.
(12) Remove upper radiator support panel.
(13) Remove front bumper assembly (Refer to 13 -
FRAMES & BUMPERS/BUMPERS/FRONT
BUMPER - REMOVAL).
Fig. 79 Combustion Deck Face Measurement
1 - STRAIGHT EDGE
2 - FEELER GAUGE
Fig. 80 Cylinder Bore Diameter
Fig. 81 Tappet Bore Diameter
9 - 268 ENGINE 5.9L DIESELBR/BE
ENGINE BLOCK (Continued)

WARNING: THE EXHAUST MANIFOLD, EXHAUST
PIPES AND CATALYTIC CONVERTER BECOME
VERY HOT DURING ENGINE OPERATION. ALLOW
ENGINE TO COOL BEFORE REMOVING OXYGEN
SENSOR.
(1) Raise and support the vehicle.
(2) Disconnect the wire connector from the O2S
sensor.
CAUTION: When disconnecting the sensor electrical
connector, do not pull directly on wire going into
sensor.
(3) Remove the O2S sensor with an oxygen sensor
removal and installation tool.
INSTALLATION
Threads of new oxygen sensors are factory coated
with anti-seize compound to aid in removal.DO
NOT add any additional anti-seize compound to
the threads of a new oxygen sensor.
(1) Install the O2S sensor. Tighten to 30 N´m (22
ft. lbs.) torque.
(2) Connect the O2S sensor wire connector.
(3) Lower the vehicle.
PTO SWITCH
DESCRIPTION
This Powertrain Control Module (PCM) input is
used only on models equipped with aftermarket
Power Take Off (PTO) units.
OPERATION
The input is used only to tell the PCM that the
PTO has been engaged. The PCM will disable (tem-
porarily shut down) certain OBD II diagnostic trou-
ble codes when the PTO is engaged.
When the aftermarket PTO switch has been
engaged, a 12V + signal is sent through circuit G113
to PCM pin A13. The PCM will then sense and deter-
mine that the PTO has been activated.
THROTTLE BODY
DESCRIPTION
The throttle body is located on the intake manifold.
Fuel does not enter the intake manifold through the
throttle body. Fuel is sprayed into the manifold by
the fuel injectors.
OPERATION
Filtered air from the air cleaner enters the intake
manifold through the throttle body. The throttle body
contains an air control passage controlled by an Idle
Air Control (IAC) motor. 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.
Certain sensors are attached to the throttle body.
The accelerator pedal cable, speed control cable and
transmission control cable (when equipped) are con-
nected to the throttle body linkage 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.
REMOVAL - 3.9L/5.2L/5.9L
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 powertrain control module (PCM).
(1) Remove the air cleaner.
(2) Disconnect throttle body electrical connectors
at MAP sensor, IAC motor and TPS (Fig. 41).
(3) Remove vacuum line at throttle body.
(4) Remove all control cables from throttle body
(lever) arm. Refer to the Accelerator Pedal and Throt-
tle Cable section of this group for additional informa-
tion.
Fig. 41 Sensor Electrical ConnectorsÐ3.9L/5.2L/5.9L
EnginesÐTypical
1 - MAP SENSOR
2 - IDLE AIR CONTROL MOTOR
3 - THROTTLE POSITION SENSOR
14 - 48 FUEL INJECTION - GASOLINEBR/BE
O2 SENSOR (Continued)

(5) Using key, crank engine over while observing
gauge. Pressure should be 5±7 psi.
(6) Re-install fuel system relay to PDC.
(7) Start engine and record fuel pressure. Pressure
should be aminimumof 69 kPa (10 psi) at idle
speed.
(8) Because fuel pump relay was removed, a Diag-
nostic Trouble Code (DTC) may have been set. After
testing is completed, and relay has been installed,
use DRB scan tool to remove DTC.
Pressure Drop Test:
(9) Shut engine off and remove test gauge from
inlet port test fitting. Re-attach 6828 test gauge to
outlet port (Fig. 55). Start engine and record fuel
pressure. Pressure should not be more than 34 kPa
(5 psi) lower than inlet port pressure test. If so,
replace fuel filter.
Fuel Supply Restriction Test:
Due to very small vacuum specifications, the DRB
scan tool along with the Periphal Expansion Port
(PEP) Module and 0±15 psi transducer must be used.
(10) Verify transfer pump pressure is OK before
performing restriction test.
(11) Locate and disconnect fuel supply line quick-
connect fitting at left-rear of engine (Fig. 56). After
disconnecting line, plastic clip will remain attached
to metal fuel line at engine. Carefully remove clip
from metal line. Snap same clip into fuel supply
hose.
(12) Install Special Rubber Adapter Hose Tool
6631 (3/8º) into ends of disconnected fuel supply line.(13) Install transducer from PEP module to brass
ªTº fitting on tool 6631.
(14) Hook up DRB scan tool to transducer.
WARNING: DO NOT STAND IN LINE WITH THE
COOLING FAN FOR THE FOLLOWING STEPS.
(15) Start engine and record vacuum reading with
engine speed at high-idle (high-idle means engine
speed is at 100 percent throttle and no load). The
fuel restriction testMUSTbe done with engine speed
at high-idle.
(16) If vacuum reading islessthan 6 in/hg. (0±152
mm hg.), test is OK. If vacuum reading ishigher
than 6 in/hg. (152 mm hg.), restriction exists in fuel
supply line or in fuel tank module. Check fuel supply
line for damage, dents or kinking. If OK, remove
module and check module and lines for blockage.
Also check fuel pump inlet filter at bottom of module
for obstructions.
Testing For Air Leaks in Fuel Supply Side:
(17) A 3±foot section of 3/8º I.D. clear tubing is
required for this test.
(18) Using a tire core valve removal tool, carefully
remove core valve from inlet fitting test port.
(19) Attach and clamp the 3/8ºclear hose to fitting
nipple.
(20) Place other end of hose into a large clear con-
tainer. Allow hose to loop as high as possibleabove
test port.
(21) The fuel transfer pump can be put into a 25
second run (test) mode if key is quickly turned to
crank position and released back to run position
without starting engine.
To prevent engine from starting in this test, first
remove fuel system relay (fuel injection pump relay).
Relay is located in Power Distribution Center (PDC).
Refer to label under PDC cover for relay location.
Because fuel pump relay was removed, a Diagnos-
tic Trouble Code (DTC) may have been set. After test-
ing is completed, and relay has been installed, use
DRB scan tool to remove DTC.
(22) Allow air to purge from empty hose before
examining for air bubbles. Air bubbles should not be
present.
(23) If bubbles are present, check for leaks in sup-
ply line to fuel tank.
(24) If supply line is not leaking, remove fuel tank
module and remove filter at bottom of module (filter
snaps to module). Check for leaks between supply
nipple at top of module, and filter opening at bottom
of module. Replace module if necessary.
(25) After performing test, install core back into
test fitting. Before installing protective cap, be sure
fitting is not leaking.
Fig. 56 Fuel Return and Supply Line Quick-Connect
Locations
1 - FUEL RETURN LINE
2 - QUICK-CONNECT FITTINGS
3 - FUEL SUPPLY LINE
14 - 82 FUEL DELIVERY - DIESELBR/BE
FUEL TRANSFER PUMP (Continued)

(b) Press in on retaining pin while pulling key
cylinder from ignition switch.
INSTALLATION
The ignition key must be in the key cylinder for
cylinder installation.
(1) Install the lock cylinder into the housing using
care to align the end of the lock cylinder with the
ignition switch.
(2) Push the lock cylinder in until it clicks.
IGNITION SWITCH
DESCRIPTION
The electrical ignition switch is located on the
steering column. It is used as the main on/off switch-
ing device for most electrical components. The
mechanical key lock cylinder is used to engage/disen-
gage the electrical ignition switch.
OPERATION
Vehicles equipped with an automatic trans-
mission and a floor mounted shifter:a cable is
used to connect the interlock device in the steering
column assembly, to the transmission floor shift
lever. This interlock device is used to lock the trans-
mission shifter in the PARK position when the key
lock cylinder is rotated to the LOCKED or ACCES-
SORY position. The interlock device within the steer-
ing column is not serviceable. If repair is necessary,
the steering column assembly must be replaced.
(Refer to 19 - STEERING/COLUMN - REMOVAL).If the ignition key is difficult to rotate to or from
the LOCK or ACCESSORY position, it may not be
the fault of the key cylinder or the steering column
components. The brake transmission shift interlock
cable may be out of adjustment. Refer to Brake
Transmission Shift Interlock Cable Adjustment in
Group 21, Transmissions for adjustment procedures.
Vehicles equipped with an automatic trans-
mission and a steering column mounted shifter:
an interlock device is located within the steering col-
umn. This interlock device is used to lock the trans-
mission shifter in the PARK position when the key
lock cylinder is in the LOCKED or ACCESSORY
position. If it is difficult to rotate the key to or from
the LOCK or ACCESSORY position, the interlock
device within the steering column may be defective.
This device is not serviceable. If repair is necessary,
the steering column assembly must be replaced.
(Refer to 19 - STEERING/COLUMN - REMOVAL).
Vehicles equipped with a manual transmis-
sion and a floor mounted shifter:on certain mod-
els, a lever is located on the steering column behind
the ignition key lock cylinder. The lever must be
manually operated to allow rotation of the ignition
key lock cylinder to the LOCK or ACCESSORY posi-
tion. If it is difficult to rotate the key to the LOCK or
ACCESSORY position, the lever mechanism may be
defective. This mechanism is not serviceable. If
repair is necessary, the steering column assembly
must be replaced. (Refer to 19 - STEERING/COL-
UMN - REMOVAL).
On other models, the ignition key cylinder must be
depressed to allow it to be rotated into the LOCK or
ACCESSORY position. If it is difficult to rotate the
key to the LOCK or ACCESSORY position, the lock
mechanism within the steering column may be defec-
tive. This mechanism is not serviceable. If repair is
necessary, the steering column assembly must be
replaced. (Refer to 19 - STEERING/COLUMN -
REMOVAL).
DIAGNOSIS AND TESTING - IGNITION SWITCH
TEST AND REPAIR
If the key removal effort is excessive on a vehicle
with a automatic transmission first adjust the shift
linkage, (Refer to 21 - TRANSMISSION/TRAN-
SAXLE/AUTOMATIC - 42RE/GEAR SHIFT CABLE -
ADJUSTMENTS).
If the ignition switch effort is excessive remove the
ignition key cylinder from the steering column. (Refer
to 19 - STEERING/COLUMN/LOCK CYLINDER
HOUSING - INSTALLATION). Check the turning
effort of the key cylinder. If the ignition key cylinder
effort is excessive replace the key cylinder. If the
Fig. 9 Retaining Pin
1 - IGNITION SWITCH
2 - KEY/KEY CYLINDER (RUN POSITION)
3 - RETAINING PIN
BR/BECOLUMN 19 - 11
LOCK CYLINDER HOUSING (Continued)

SHIFT PATTERN
The shift pattern is in a modified H pattern (Fig.
2). Overdrive fifth and reverse gears are in line and
outboard of the first through fourth gear positions.
GEAR RATIOS
GEAR RATIO
FIRST 5.61:1
SECOND 3.04:1
THIRD 1.67:1
FOURTH 1.00:1
FIFTH 0.75:1
REVERSE 5.04:1
IDENTIFICATION
The transmission identification tag is attached to
the driver side PTO cover (Fig. 3).
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.
OPERATION
The manual transmission receives power through
the clutch assembly from the engine. The clutch disc
is splined to the transmission input shaft and is
turned at engine speed at all times that the clutch is
engaged. The input shaft is connected to the trans-
mission countershaft through the mesh of fourth
speed gear on the input shaft and the fourth counter-
shaft gear. At this point, all the transmission gears
are spinning.
The driver selects a particular gear by moving the
shift lever to the desired gear position. This move-
ment moves the internal transmission shift compo-
nents to begin the shift sequence. As the shift lever
moves the selected shift rail, the shift fork attached
to that rail begins to move. The fork is positioned in
a groove in the outer circumference of the synchro-
nizer sleeve. As the shift fork moves the synchronizer
sleeve, the synchronizer begins to speed-up or slowdown the selected gear (depending on whether we are
up-shifting or down-shifting). The synchronizer does
this by having the synchronizer hub splined to the
mainshaft, or the countershaft in some cases, and
moving the blocker ring into contact with the gear's
friction cone. As the blocker ring and friction cone
come together, the gear speed is brought up or down
to the speed of the synchronizer. As the two speeds
match, the splines on the inside of the synchronizer
sleeve become aligned with the teeth on the blocker
ring and the friction cone and eventually will slide
over the teeth, locking the gear to the mainshaft, or
countershaft, through the synchronizer.
DIAGNOSIS AND TESTING - MANUAL
TRANSMISSION
LOW LUBRICANT LEVEL
A low transmission lubricant level is generally the
result of a leak, inadequate lubricant fill or an incor-
rect lubricant level check.
Leaks can occur at the mating surfaces of the gear
case, adaptor or extension housing, or from the front/
rear seals. A suspected leak could also be the result
of an overfill condition.
Leaks at the rear of the extension or adapter hous-
ing will be from the housing oil seals. Leaks at com-
ponent mating surfaces will probably be the result of
inadequate sealer, gaps in the sealer, incorrect bolt
tightening or use of a non-recommended sealer.
Fig. 2 NV4500
Fig. 3 Identification Tag Location
1 - PTO COVER
2 - I.D. TAG
21 - 46 MANUAL - NV4500BR/BE
MANUAL - NV4500 (Continued)

ELINE/PROPELLER SHAFT/PROPELLER SHAFT -
REMOVAL)
(12) Disconnect wires from park/neutral position
switch and transmission solenoid.
(13) Disconnect gearshift rod and torque shaft
assembly from transmission.
(14) Disconnect throttle valve cable from transmis-
sion bracket and throttle valve lever.
(15) On4x4models, disconnect shift rod from
transfer case shift lever.
(16)
Support rear of engine with safety stand or jack.
(17) Raise transmission slightly with service jack
to relieve load on crossmember and supports.
(18) Remove bolts securing rear support and cush-
ion to transmission and crossmember. Raise trans-
mission slightly, slide exhaust hanger arm from
bracket (Fig. 15) and remove rear support.
(19) Remove bolts attaching crossmember to frame
and remove crossmember.
(20) On4x4models, remove transfer case with
transmission jack or aid of helper.
(21) Remove all converter housing bolts.
(22) Carefully work transmission and torque con-
verter assembly rearward off engine block dowels.
(23) Lower transmission and remove assembly
from under the vehicle.
(24) To remove torque converter, remove C-clamp
from edge of bell housing and carefully slide torque
converter out of the transmission.
DISASSEMBLY
(1) Clean transmission exterior with steam gun or
with solvent. Wear eye protection during cleaning
operations.
(2) Place transmission in a vertical position.(3)
Measure input shaft end play as follows (Fig. 16).
(a) Attach Adapter 8266-6 to Handle 8266-8.
(b) Attach dial indicator C-3339 to Handle
8266-8.
(c)
Install the assembled tool onto the input shaft
of the transmission and tighten the retaining screw
on Adapter 8266-6 to secure it to the input shaft.
(d)Position the dial indicator plunger against a
flat spot on the oil pump and zero the dial indicator.
(e) Move the input shaft in and out. Record the
maximum travel for assembly reference.
Fig. 14 Fill Tube Attachment
1 - TRANSFER CASE VENT TUBE
2 - FILL TUBE (V8)
3 - TUBE SEAL
4 - FILL TUBE (V6)Fig. 15 Rear Support Cushion
1 - EXHAUST PIPE ARM AND BRACKET
2 - CROSSMEMBER
3 - REAR SUPPORT AND CUSHION
Fig. 16 Checking Input Shaft End Play
1 - TOOL 8266-8
2 - TOOL 8266-6
3 - TOOL C-3339
21 - 160 AUTOMATIC TRANSMISSION - 42REBR/BE
AUTOMATIC TRANSMISSION - 42RE (Continued)

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 higher
than 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.
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ELECTRONIC GOVERNOR (Continued)

OVERDRIVE OFF SWITCH
DESCRIPTION
The overdrive OFF (control) switch is located in
the shift lever arm (Fig. 114). The switch is a
momentary contact device that signals the PCM to
toggle current status of the overdrive function.
OPERATION
At key-on, overdrive operation is allowed. Pressing
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 a 3-4
upshift. The control switch indicator light illuminates
only when the overdrive switch is turned to the OFF
position, or when illuminated by the transmission
control module.
DIAGNOSIS AND TESTING - OVERDRIVE
ELECTRICAL CONTROLS
The overdrive off switch, valve body solenoid, case
connectors and related wiring can all be tested with
a 12 volt test lamp or a volt/ohmmeter. Check conti-
nuity of each component when diagnosis indicates
this is necessary.
Switch and solenoid continuity should be checked
whenever the transmission fails to shift into fourth
gear range.
REMOVAL
(1) Using a plastic trim tool, remove the overdrive
off switch retainer from the shift lever (Fig. 115).(2) Pull the switch outwards to release it from the
connector in the lever (Fig. 116)
INSTALLATION
NOTE: There is enough slack in the wire to pull out
the connector from the lever.
(1) Pull the connector out of the lever just enough
to grasp it.
CAUTION: Be careful not to bend the pins on the
overdrive off switch. Use care when installing the
switch, as it is not indexed, and can be accidentally
installed incorrectly.
Fig. 114 Overdrive Off Switch
Fig. 115 Overdrive Off Switch Retainer
1 - GEAR SHIFT LEVER
2 - OVERDRIVE OFF SWITCH RETAINER
3 - PLASTIC TRIM TOOL
Fig. 116 Remove the Overdrive Off Switch
1 - GEAR SHIFT LEVER
2 - OVERDRIVE OFF SWITCH
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