JEEP YJ 1995 Service And Repair Manual

(73) Assemble and install accumulator pistons and
springs (Fig. 57).
(74) Install new check ball body and spring (Fig.
58).
(75) Position valve body on case (Fig. 59).(76) Install detent spring (Fig. 59).
(77) Align manual valve, detent spring and shift
sector (Fig. 59).
(78) Connect transmission throttle cable to throttle
valve cam (Fig. 60).
(79) Install and tighten valve body-to-case bolts to
10 Nzm (7 ft. lbs.) torque.
(80) Connect valve body solenoid wires to solenoids
(Fig. 61).
(81) Install new O-ring on solenoid harness
adapter and secure adapter to case.
(82) Install valve body oil tubes (Fig. 62). Tap
tubes into place with a plastic mallet. Be sure the
flanged tube ends and straight tube ends are in-
stalled as shown.
Fig. 57 Accumulator Piston And Spring Installation
Fig. 58 Installing Check Ball Body And Spring
Fig. 59 Aligning Manual Valve, Shift Sector And
Detent Spring
Fig. 60 Connecting Transmission Throttle Cable
JAW-4 TRANSMISSION OVERHAUL 21 - 279

(83) Install new gaskets on oil screen and install
screen on valve body. Tighten screen bolts to 10 Nzm
(7 ft. lbs.) torque.
(84) Install magnet in oil pan. Be sure magnet
does not interfere with valve body oil tubes.
(85) Apply Loctite 599 to sealing surface of oil pan.
Sealer bead should be at least 3 mm (1/8 in.) wide.
Install pan on case and tighten pan bolts to 7 Nzm
(65 in. lbs.) torque.
(86) Install transmission speed sensor rotor and
key on output shaft (Fig. 63).
(87) Install spacer and speedometer drive gear on
output shaft. Then install retaining snap ring (Fig.
64).
(88) Apply bead of Loctite 599 sealer to sealing
surface at rear of case (Fig. 65).(89) Install adapter housing on transmission.
Tighten adapter bolts to 34 Nzm (25 ft. lbs.) torque.
(90) Install transmission speed sensor (Fig. 66).
Tighten sensor bolt to 7.4 Nzm (65 in. lbs.) torque
and connect sensor wire harness connector.
(91) Install converter housing (Fig. 67). Tighten 12
mm diameter housing bolts to 57 Nzm (42 ft. lbs.)
torque. Tighten 10 mm diameter housing bolts to 34
Nzm (25 ft. lbs.) torque.
(92) Install transmission shift lever on manual
valve shaft. Do not install lever attaching nut at this
time.
(93) Move transmission shift lever fully rearward.
Then move lever two detent positions forward.
Fig. 61 Connecting Valve Body Solenoid Wires
Fig. 62 Installing Valve Body Oil Tubes
Fig. 63 Installing Transmission Speed Sensor Rotor
And Key
Fig. 64 Installing Spacer And Speedometer Drive
Gear
21 - 280 AW-4 TRANSMISSION OVERHAULJ

(94) Mount park/neutral position switch on manual
valve shaft and tighten switch adjusting bolt just
enough to keep switch from moving (Fig. 68).
(95) Install park/neutral position switch tabbed
washer and retaining nut (Fig. 68). Tighten nut to
6.9 Nzm (61 in. lbs.) torque, but do not bend any of
the washer tabs against the nut at this time.
(96) Align park/neutral position switch standard
line with groove or flat on manual shaft (Fig. 68).(97) Tighten park/neutral position switch adjusting
bolt to 13 Nzm (9 ft. lbs.) torque.
(98) Install transmission shift lever on manual
valve shaft. Tighten lever attaching nut to 16 Nzm
(12 ft. lbs.) torque.
Fig. 65 Applying Sealer To Case Rear Flange
Fig. 66 Installing Transmission Speed Sensor
Fig. 67 Installing Converter Housing
Fig. 68 Park/Neutral Position Switch Installation/
Adjustment
JAW-4 TRANSMISSION OVERHAUL 21 - 281

(99) Install retaining clamp for wire harness and
throttle cable (Fig. 69).
(100) Install torque converter.
(101) Verify that converter is seated by measuring
distance between converter housing flange and one of
the converter mounting pads (Fig. 70). Use straight-
edge and vernier calipers to measure distance. On
6-cyl. transmissions, distance should be 16.5 mm
(0.650 in.).
(102) Secure converter in transmission with
C-clamp or metal strapping. Do this before mounting
transmission on jack or moving transmission under
vehicle.(103) Install lower half of transmission fill tube (in-
stall upper half after transmission is in vehicle).
CAUTION: The transmission cooler and lines must
be reverse flushed if overhaul corrected a malfunc-
tion that generated sludge, metal particles, or
clutch friction material. The torque converter should
also be replaced if contaminated by the same mal-
function. Debris and residue not flushed from the
cooler and lines will flow back into the transmission
and converter. The result will be a repeat failure and
shop comeback.
Fig. 69 Installing Cable/Harness Clamps
Fig. 70 Checking Converter Installation
21 - 282 AW-4 TRANSMISSION OVERHAULJ

NP231 TRANSFER CASE
INDEX
page page
General Information....................... 283
Overhaul Cleaning and Inspection............ 294
Shift Lever Installation (XJ)................. 286
Shift Lever Installation (YJ)................. 286
Shift Lever Removal (XJ)................... 286
Shift Lever Removal (YJ)................... 286
Shift Linkage Adjustment................... 286Speedometer Service..................... 287
Transfer Case Assembly................... 294
Transfer Case Disassembly and Overhaul...... 289
Transfer Case Identification................. 284
Transfer Case Installation.................. 288
Transfer Case Lubricant and Fill Level......... 284
Transfer Case Removal.................... 287
GENERAL INFORMATION
The NP231 is a part-time transfer case with a low
range reduction gear system (Fig. 1). The NP231 has
three operating ranges plus a Neutral position. A low
range system provides a reduction ratio for increased
low speed torque capability.The NP231 is the Command Trac transfer case. It
is used in XJ and YJ models. Two versions are used.
One version retains the synchronizer components
used in previous models. A newly introduced version
is not equipped with synchro components.
Fig. 1 NP231 Transfer Case
JNP231 TRANSFER CASE 21 - 283

OPERATING RANGES
NP231 operating ranges are: 2-wheel drive high;
4-wheel drive high and 4-wheel drive low.
2-wheel drive range is for use on all road surfaces.
The 4-wheel drive high and low ranges are undiffer-
entiated and should only be used on unpaved, low
traction surfaces only. The only exception being when
hard surface roads are snow and ice covered.
SHIFT MECHANISM
Operating ranges are selected with a floor mounted
shift lever. The shift lever is connected to the trans-
fer case range lever by an adjustable linkage rod. A
straight line shift pattern is used. Range positions
are marked on the shifter bezel cover plate, or on the
shift knob.
TRANSFER CASE IDENTIFICATION
A circular ID tag is attached to the rear case of
each NP231 transfer case (Fig. 2). The ID tag pro-
vides 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
7-10-94 would represent July 10, 1994.TRANSFER CASE LUBRICANT AND FILL LEVEL
Recommended lubricant for the NP231 transfer
case is Mopar Dexron II.
Approximate lubricant refill capacity is 1.54 liters
(3.25 pints) for YJ and 1.04 liters (2.2 pints) for XJ.
Correct fill level is to the bottom edge of the fill
plug hole. Be sure the vehicle is level to ensure an
accurate fluid level check.
Fig. 2 Transfer Case Identification Tag
21 - 284 NP231 TRANSFER CASEJ

NP231 SERVICE DIAGNOSIS
JNP231 TRANSFER CASE 21 - 285

SHIFT LINKAGE ADJUSTMENT
(1) Shift transfer case into 4L position.
(2) Raise vehicle.
(3) Loosen lock bolt on adjusting trunnion (Figs. 3
and 4).
4) Be sure linkage rod slides freely in trunnion.
Clean rod and apply spray lube if necessary.
(5) Verify that transfer case range lever is fully en-
gaged in 4L position.
(6) Tighten adjusting trunnion lock bolt.
(7) Lower vehicle.
SHIFT LEVER REMOVAL (XJ)
(1) Shift transfer case into 4L.
(2) Raise vehicle.
(3) Loosen adjusting trunnion locknut and slide
shift rod out of trunnion (Fig. 4). If rod lacks enough
travel to come out of trunnion, push trunnion out of
torque shaft.
(4) Lower vehicle.
(5) Remove console. Refer to park brake section in
Group 5 for procedures.
(6) Remove screws attaching lever assembly to
floorpan and remove assembly and shift rod (if left
attached).
SHIFT LEVER INSTALLATION (XJ)
(1) If shift rod was not removed from lever assem-
bly, work rod down through floorpan opening. Then
position lever assembly on floorpan and install as-
sembly attaching screws.
(2) Install console.
(3) Raise vehicle.
(4) Connect trunnion to torque shaft arm. Or, slide
shift rod into trunnion on range lever. Be sure shift
rod slides freely in trunnion.
(5) Verify that range lever is in 4L position. Then
tighten trunnion lock bolt.(6) Lower vehicle and check transfer case shift op-
eration.
SHIFT LEVER REMOVAL (YJ)
(1) Shift transfer case into neutral.
(2) Remove shift lever knob and retaining nut.
Then remove shift lever boot and bezel.
(3) Raise vehicle
(4) Loosen lock bolt in adjusting trunnion and slide
shift rod out of trunnion (Fig. 3).
(5) Remove bolts/nuts attaching bracket and brace
assembly to transmission (Fig. 5).
(6) Remove shift lever and bracket as assembly.
(7) YJ shift lever assembly is serviceable. If any
assembly part must be replaced, remove pivot bolt,
lever pin E-clip, and lever pin and spring. Then dis-
assemble and replace necessary part (Fig. 6).
SHIFT LEVER INSTALLATION (YJ)
(1) Assemble lever components, if necessary. Lube
pivot bolt and pin with Mopar multi-mileage grease
before installation.
(2) Work shift lever upward into vehicle interior.
Then position lever and bracket assembly on trans-
mission and install attaching bolts/nuts.
(3) Place transfer case range lever in 4L position.
Then slide shift rod into trunnion and tighten lock
bolt.
Fig. 3 Adjusting Trunnion And Lock Bolt (YJ)
Fig. 4 Shift Linkage (XJ)
21 - 286 NP231 TRANSFER CASEJ

(4) Lower vehicle.
(5) Install shift lever bezel and boot (Fig. 7). Then
install retaining nut and shift knob on lever.
SPEEDOMETER SERVICE
Speedometer service is covered in the 30RH/32RH,
or AW-4 automatic transmission sections in this
group. Refer to the appropriate section as needed.
TRANSFER CASE REMOVAL
(1) Shift transfer case into Neutral.
(2) Raise vehicle.
(3) Drain transfer case lubricant.
(4) Mark front and rear propeller shaft yokes for
alignment reference.
(5) Support transmission with jack stand.
(6) Remove rear crossmember, or skid plate.
(7) Disconnect front/rear propeller shafts at trans-
fer case.
(8) Disconnect vehicle speed sensor wires.
(9) Disconnect transfer case linkage rod from range
lever.
(10) Disconnect transfer case vent hose, and indi-
cator or vacuum switch harness.
(11) Support transfer case with transmission jack.
(12) Remove nuts attaching transfer case to trans-
mission.
(13) Secure transfer case to jack with chains.
Fig. 5 Shift Linkage Mounting (YJ)
Fig. 6 Shift Linkage (YJ)
JNP231 TRANSFER CASE 21 - 287

(14) Pull transfer case and jack rearward to disen-
gage transfer case.
(15) Remove transfer case from under vehicle.
(16) If transfer case was removed for overhaul, re-
move damper from rear retainer.
TRANSFER CASE INSTALLATION
(1) Mount transfer case on a transmission jack. Se-
cure transfer case to jack with chains.
(2) Position transfer case under vehicle.(3) Align transfer case and transmission shafts and
install transfer case on transmission.
(4) Install and tighten transfer case attaching nuts
to 35 Nzm (26 ft. lbs.) torque.
(5) Install damper on rear retainer (Fig. 8).
Tighten damper attaching nuts to 54 Nzm (40 ft. lbs.)
torque.
(6) Connect vehicle speed sensor wires, and vent
hose.
(7) Connect indicator or vacuum switch harness to
transfer case switch. Secure wire harnesses to clips
on transfer case.
(8) Align and connect propeller shafts. Tighten
shaft attaching bolts to 19 Nzm (170 in. lbs.) torque.
(9) Fill transfer case with Mopar Dexron II fluid.
(10) Install rear crossmember, or skid plate.
Tighten crossmember bolts to 41 Nzm (30 ft. lbs.)
torque.
(11) Remove transmission jack and support stand.
(12) Connect shift rod to transfer case range lever.
(13) Adjust transfer case shift linkage.
(14) Lower vehicle and verify transfer case shift
operation.
Fig. 7 Transfer Case Shift Lever And Boots (YJ)
Fig. 8 Transfer Case Mounting
21 - 288 NP231 TRANSFER CASEJ