Content .. 488 489 490 491 ..

Jeep Grand Cherokee WJ. Manual - part 490

(3) Adjust throttle and gearshift linkage if com-

plaint was based on delayed, erratic, or harsh shifts.

(4) Road test and note how transmission upshifts,

downshifts, and engages.

(5) Perform stall test if complaint is based on slug-

gish acceleration. Or, if abnormal throttle opening is
needed to maintain normal speeds with a properly
tuned engine.

(6) Perform hydraulic pressure test if shift prob-

lems were noted during road test.

(7) Perform air-pressure test to check clutch-band

operation.

VEHICLE IS DISABLED

(1) Check fluid level and condition.
(2) Check for broken or disconnected gearshift or

throttle linkage.

(3) Check for cracked, leaking cooler lines, or loose

or missing pressure-port plugs.

(4) Raise and support vehicle on safety stands,

start engine, shift transmission into gear, and note
following:

(a) If propeller shaft turns but wheels do not,

problem is with differential or axle shafts.

(b) If propeller shaft does not turn and transmis-

sion is noisy, stop engine. Remove oil pan, and
check for debris. If pan is clear, remove transmis-
sion and check for damaged drive plate, converter,
oil pump, or input shaft.

sion is not noisy, perform hydraulic-pressure test to
determine if problem is hydraulic or mechanical.

PARK/NEUTRAL POSITION SWITCH

The center terminal of the park/neutral position

switch is the sense/starter-circuit terminal. It pro-
vides the ground for the starter solenoid circuit when
the transmission selector lever is in PARK or NEU-
TRAL positions only. The outer terminals on the
switch are for the backup lamp circuit.

SWITCH TEST

To test the switch, remove the wiring connector.

Test for continuity between the center terminal and
the transmission case. Continuity should exist when
the transmission is in PARK or NEUTRAL only. Con-
tinuity should not exist any other time or with the
transmission in any other gear.

Shift the transmission into REVERSE and test

continuity at the switch outer terminals. Continuity
should exist when the transmission is in REVERSE
only. Continuity should not exist between the outer
terminals and the case.

Check gearshift linkage adjustment before replac-

ing a switch that tests faulty.

OVERDRIVE ELECTRICAL CONTROLS

The overdrive off switch, valve body solenoid, case con-

nectors and related wiring can all be tested with a 12
volt test lamp or a volt/ohmmeter. Check continuity of
each component when diagnosis indicates this is neces-
sary. Refer to Group 8W, Wiring Diagrams, for component
locations and circuit information.

Switch and solenoid continuity should be checked

whenever the transmission fails to shift into fourth
gear range.

BRAKE TRANSMISSION SHIFT INTERLOCK

(1) Verify that the key can only be removed in the

PARK position

(2) When the shift lever is in PARK And the shift

handle pushbutton is in the “OUT” position, the igni-
tion key cylinder should rotate freely from OFF to
LOCK. When the shifter is in any other gear or neu-
tral position, the ignition key cylinder should not
rotate to the LOCK position.

(3) Shifting out of PARK should be possible when

the ignition key cylinder is in the OFF position.

(4) Shifting out of PARK should not be possible

while applying 25 lb. maximum handle pushbutton
force and ignition key cylinder is in the RUN or
START positions unless the foot brake pedal is
depressed approximately 1/2 inch (12mm).

(5) Shifting out of PARK should not be possible

when the ignition key cylinder is in the ACCESSORY
or LOCK positions.

(6) Shifting between any gears, NEUTRAL or into

PARK may be done without depressing foot brake
pedal with ignition switch in RUN or START posi-
tions and vehicle stationary or in motion.

GEARSHIFT CABLE

(1) The floor shifter lever and gate positions

should be in alignment with all transmission PARK,
NEUTRAL, and gear detent positions.

(2) Engine starts must be possible with floor shift

lever in PARK or NEUTRAL gate positions only. Engine
starts must not be possible in any other gear position.

(3) With floor shift lever handle push-button not

depressed and lever in:

(a) PARK position—Apply forward force on cen-

ter of handle and remove pressure. Engine starts
must be possible.

(b) PARK position—Apply rearward force on cen-

ter of handle and remove pressure. Engine starts
must be possible.

starts must be possible.

(d) NEUTRAL position—Engine

running

and

brakes applied, apply forward force on center of
shift handle. Transmission shall not be able to shift
from neutral to reverse.

21 - 10

TRANSMISSION AND TRANSFER CASE

DIAGNOSIS AND TESTING (Continued)

2000 JEEP GRAND CHEROKEE

THROTTLE VALVE CABLE

Transmission throttle valve cable adjustment is

extremely important to proper operation. This adjust-
ment positions the throttle valve, which controls shift
speed, quality, and part-throttle downshift sensitivity.

If cable setting is too loose, early shifts and slip-

page between shifts may occur. If the setting is too
tight, shifts may be delayed and part throttle down-
shifts may be very sensitive. Refer to the Adjust-
ments section for the proper adjustment procedure.

ROAD TESTING

Before road testing, be sure the fluid level and con-

trol

cable

adjustments

have

been

checked

and

adjusted if necessary. Verify that diagnostic trouble
codes have been resolved.

Observe engine performance during the road test.

A poorly tuned engine will not allow accurate analy-
sis of transmission operation.

Operate the transmission in all gear ranges. Check

for shift variations and engine flare which indicates
slippage. Note if shifts are harsh, spongy, delayed,
early, or if part throttle downshifts are sensitive.

Slippage indicated by engine flare, usually means

clutch, band or overrunning clutch problems. If the
condition is advanced, an overhaul will be necessary
to restore normal operation.

A slipping clutch or band can often be determined

by comparing which internal units are applied in the
various gear ranges. The Clutch and Band Applica-
tion chart provides a basis for analyzing road test
results.

SHIFT

LEVER

POSITION

TRANSMISSION CLUTCHES AND BANDS

OVERDRIVE CLUTCHES

FRONT

CLUTCH

FRONT

BAND

REAR

CLUTCH

REAR
BAND

OVERRUN.

CLUTCH

OVERDRIVE

CLUTCH

DIRECT

CLUTCH

OVERRUN.

CLUTCH

Reverse

Drive Range

First

Second

Third

Fourth

2-Range
(Manual
Second)

1-Range
(Manual Low)

CLUTCH AND BAND APPLICATION CHART

ANALYZING ROAD TEST

Refer to the Clutch and Band Application chart

and note which elements are in use in the various
gear ranges.

Note that the rear clutch is applied in all forward

ranges (D, 2, 1). The transmission overrunning clutch
is applied in first gear (D, 2 and 1 ranges) only. The
rear band is applied in 1 and R range only.

Note that the overdrive clutch is applied only in

fourth gear and the overdrive direct clutch and over-
running clutch are applied in all ranges except fourth
gear.

For example: If slippage occurs in first gear in D

and 2 range but not in 1 range, the transmission
overrunning clutch is faulty. Similarly, if slippage
occurs in any two forward gears, the rear clutch is
slipping.

Applying the same method of analysis, note that

the front and rear clutches are applied simulta-

neously only in D range third and fourth gear. If the
transmission slips in third gear, either the front
clutch or the rear clutch is slipping.

If the transmission slips in fourth gear but not in

third gear, the overdrive clutch is slipping. By select-
ing another gear which does not use these clutches,
the slipping unit can be determined. For example, if
the transmission also slips in Reverse, the front
clutch is slipping. If the transmission does not slip in
Reverse, the rear clutch is slipping.

If slippage occurs during the 3-4 shift or only in

fourth gear, the overdrive clutch is slipping. Simi-
larly, if the direct clutch were to fail, the transmis-
sion would lose both reverse gear and overrun
braking in 2 position (manual second gear).

If the transmission will not shift to fourth gear, the

control switch, overdrive solenoid or related wiring
may also be the problem cause.

TRANSMISSION AND TRANSFER CASE

21 - 11

DIAGNOSIS AND TESTING (Continued)

2000 JEEP GRAND CHEROKEE

This process of elimination can be used to identify

a slipping unit and check operation. Proper use of
the Clutch and Band Application Chart is the key.

Although road test analysis will help determine the

slipping unit, the actual cause of a malfunction usu-
ally cannot be determined until hydraulic and air
pressure tests are performed. Practically any condi-
tion can be caused by leaking hydraulic circuits or
sticking valves.

Unless a malfunction is obvious, such as no drive

in D range first gear, do not disassemble the trans-
mission. Perform the hydraulic and air pressure tests
to help determine the probable cause.

HYDRAULIC PRESSURE TEST

Hydraulic test pressures range from a low of one

psi (6.895 kPa) governor pressure, to 300 psi (2068
kPa) at the rear servo pressure port in reverse.

An accurate tachometer and pressure test gauges

are required. Test Gauge C-3292 has a 100 psi range.
Test Gauge C-3293-SP has a 300 psi range and is
used where pressures exceed 100 psi.

Pressure Test Port Locations

Test ports are located at both sides of the transmis-

sion case (Fig. 7).

Line pressure is checked at the accumulator port

on the right side of the case. The front servo pressure
port is at the right side of the case just behind the
filler tube opening.

The rear servo and governor pressure ports are at

the right rear of the transmission case. The overdrive
clutch pressure port is at the left rear of the case.

Test One - Transmission In Manual Low

NOTE: This test checks pump output, pressure reg-
ulation, and condition of the rear clutch and servo
circuit. Both test gauges are required for this test.

(1) Connect tachometer to engine. Position tachom-

eter so it can be observed from driver seat if helper
will be operating engine. Raise vehicle on hoist that
will allow rear wheels to rotate freely.

(2) Connect 100 psi Gauge C-3292 to accumulator

port. Then connect 300 psi Gauge C-3293-SP to rear
servo port.

(3) Disconnect throttle and gearshift cables from

levers on transmission valve body manual shaft.

(4) Have helper start and run engine at 1000 rpm.
(5) Move transmission shift lever fully forward

into 1 range.

(6) Gradually move transmission throttle lever

from full forward to full rearward position and note
pressures on both gauges:

• Line pressure at accumulator port should be

54-60 psi (372-414 kPa) with throttle lever forward
and gradually increase to 90-96 psi (621-662 kPa) as
throttle lever is moved rearward.

• Rear servo pressure should be same as line pres-

sure within 3 psi (20.68 kPa).

Test Two—Transmission In 2 Range

NOTE: This test checks pump output, line pressure
and pressure regulation. Use 100 psi Test Gauge
C-3292 for this test.

(1) Leave vehicle in place on hoist and leave Test

Gauge C-3292 connected to accumulator port.

(2) Have helper start and run engine at 1000 rpm.
(3) Move transmission shift lever one detent rear-

ward from full forward position. This is 2 range.

(4) Move transmission throttle lever from full for-

ward to full rearward position and read pressure on
gauge.

Fig. 7 Pressure Test Port Locations

1 – OVERDRIVE CLUTCH TEST PORT
2 – GOVERNOR TEST PORT
3 – ACCUMULATOR TEST PORT
4 – FRONT SERVO TEST PORT
5 – REAR SERVO TEST PORT

21 - 12

TRANSMISSION AND TRANSFER CASE

DIAGNOSIS AND TESTING (Continued)

2000 JEEP GRAND CHEROKEE

(5) Line pressure should be 54-60 psi (372-414

kPa) with throttle lever forward and gradually
increase to 90-96 psi (621-662 kPa) as lever is moved
rearward.

Test Three—Transmission In D Range Third Gear

NOTE: This test checks pressure regulation and
condition of the clutch circuits. Both test gauges
are required for this test.

(1) Turn OD switch off.
(2) Leave vehicle on hoist and leave Gauge C-3292

in place at accumulator port.

(3) Move Gauge C-3293-SP over to front servo port

for this test.

(4) Have helper start and run engine at 1600 rpm

for this test.

(5) Move transmission shift lever two detents rear-

ward from full forward position. This is D range.

(6) Read pressures on both gauges as transmission

throttle lever is gradually moved from full forward to
full rearward position:

• Line pressure at accumulator in D range third

gear, should be 54-60 psi (372-414 kPa) with throttle
lever forward and increase as lever is moved rear-
ward. If the torque convertor is allowed to lock up
pressure can rise to 130 psi (900 kPa). Be certain to
maintain the correct RPM during testing.

• Front servo pressure in D range third gear,

should be within 3 psi (21 kPa) of line pressure up to
kickdown point.

Test Four—Transmission In Reverse

NOTE: This test checks pump output, pressure reg-
ulation and the front clutch and rear servo circuits.
Use 300 psi Test Gauge C-3293-SP for this test.

(1) Leave vehicle on hoist and leave gauge C3292

in place at accumulator port.

(2) Move 300 psi Gauge C-3293-SP back to rear

servo port.

(3) Have helper start and run engine at 1600 rpm

for test.

(4) Move transmission shift lever four detents

rearward from full forward position. This is Reverse
range.

(5) Move transmission throttle lever fully forward

then fully rearward and note reading at Gauge
C-3293-SP.

(6) Pressure should be 145 - 175 psi (1000-1207

kPa) with throttle lever forward and increase to 230 -
280 psi (1586-1931 kPa) as lever is gradually moved
rearward.

Test Five—Governor Pressure

NOTE: This test checks governor operation by
measuring governor pressure response to changes
in vehicle speed. It is usually not necessary to
check governor operation unless shift speeds are
incorrect or if the transmission will not downshift.
The test should be performed on the road or on a
hoist that will allow the rear wheels to rotate freely.

(1) Move 100 psi Test Gauge C-3292 to governor

pressure port.

(2) Move transmission shift lever two detents rear-

ward from full forward position. This is D range.

(3) Have helper start and run engine at curb idle

speed. Then firmly apply service brakes so wheels
will not rotate.

(4) Note governor pressure:
• Governor pressure should be no more than 20.6

kPa (3 psi) at curb idle speed and wheels not rotat-
ing.

• If pressure exceeds 20.6 kPa (3 psi), a fault

exists in governor pressure control system.

(5) Release brakes, slowly increase engine speed,

and observe speedometer and pressure test gauge (do
not exceed 30 mph on speedometer). Governor pres-
sure should increase in proportion to vehicle speed.
Or approximately 6.89 kPa (1 psi) for every 1 mph.

(6) Governor pressure rise should be smooth and

drop back to no more than 20.6 kPa (3 psi), after
engine returns to curb idle and brakes are applied to
prevent wheels from rotating.

(7) Compare results of pressure test with analysis

chart.

Test Six—Transmission In Overdrive Fourth Gear

NOTE: This test checks line pressure at the over-
drive clutch in fourth gear range. Use 300 psi Test
Gauge C-3292 for this test. The test should be per-
formed on the road or on a chassis dyno.

(1) Remove tachometer; it is not needed for this

test.

(2) Move 300 psi Gauge to overdrive clutch pres-

sure test port. Then remove other gauge and reinstall
test port plug.

(3) Lower vehicle.
(4) Turn OD switch on.
(5) Secure test gauge so it can be viewed from

drivers seat.

(6) Start engine and shift into D range.
(7) Increase vehicle speed gradually until 3-4 shift

occurs and note gauge pressure.

(8) Pressure should be 469-496 kPa (68-72 psi)

with closed throttle and increase to 620-827 kPa (90-
120 psi) at 1/2 to 3/4 throttle. Note that pressure can
increase to around 896 kPa (130 psi) at full throttle.

TRANSMISSION AND TRANSFER CASE

21 - 13

DIAGNOSIS AND TESTING (Continued)

2000 JEEP GRAND CHEROKEE

Content .. 488 489 490 491 ..