2002 JEEP GRAND CHEROKEE check engine

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 C-3292
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 mea-
suring governor pressure response to changes in
vehicle speed. It is usually not necessary to check
governor operation unless shift speeds are incor-
rect 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:
²Governor pressure should be no more than 20.6
kPa (3 psi) at curb idle speed and wheels not rotat-
ing.
²If 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-3293-SP for this test. The test should be
performed 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.
(9) Return to shop or move vehicle off chassis
dyno.
PRESSURE TEST ANALYSIS CHART
TEST CONDITION INDICATION
Line pressure OK during
any one testPump and regulator
valve OK
Line pressure OK in R
but low in D, 2, 1Leakage in rear clutch
area (seal rings, clutch
seals)
Pressure low in D Fourth
Gear RangeOverdrive clutch piston
seal, or check ball
problem
Pressure OK in 1, 2 but
low in D3 and RLeakage in front clutch
area
Pressure OK in 2 but low
in R and 1Leakage in rear servo
Front servo pressure in 2 Leakage in servo; broken
servo ring or cracked
servo piston
Pressure low in all
positionsClogged filter, stuck
regulator valve, worn or
faulty pump, low oil level
Governor pressure too
high at idle speedGovernor pressure
solenoid valve system
fault. Refer to diagnostic
book.
21 - 14 AUTOMATIC TRANSMISSION - 42REWJ
AUTOMATIC TRANSMISSION - 42RE (Continued)

DIAGNOSIS CHARTS
CONDITION POSSIBLE CAUSES CORRECTION
HARSH
ENGAGEMENT
(FROM NEUTRAL TO
DRIVE OR REVERSE)1. Fluid Level Low. 1. Add Fluid
2. Throttle Linkage Mis-adjusted. 2. Adjust linkage - setting may be too long.
3. Mount and Driveline Bolts
Loose.3. Check engine mount, transmission mount,
propeller shaft, rear spring to body bolts, rear
control arms, crossmember and axle bolt torque.
Tighten loose bolts and replace missing bolts.
4. U-Joint Worn/Broken. 4. Remove propeller shaft and replace U-Joint.
5. Axle Backlash Incorrect. 5. Check per Service Manual. Correct as needed.
6. Hydraulic Pressure Incorrect. 6. Check pressure. Remove, overhaul or adjust
valve body as needed.
7. Band Mis-adjusted. 7. Adjust rear band.
8. Valve Body Check Balls Missing. 8. Inspect valve body for proper check ball
installation.
9. Axle Pinion Flange Loose. 9. Replace nut and check pinion threads before
installing new nut. Replace pinion gear if threads
are damaged.
10. Clutch, band or planetary
component damaged.10. Remove, disassemble and repair transmission
as necessary.
11. Converter Clutch Faulty. 11. Replace converter and flush cooler and line
before installing new converter.
DELAYED
ENGAGEMENT
(FROM NEUTRAL TO
DRIVE OR REVERSE)1. Fluid Level Low. 1. Correct level and check for leaks.
2. Filter Clogged. 2. Change filter.
3. Gearshift Linkage Mis-adjusted. 3. Adjust linkage and repair linkage if worn or
damaged.
4. Torque Converter Drain Back
(Oil drains from torque converter
into transmission sump).4. If vehicle moves normally after 5 seconds after
shifting into gear, no repair is necessary. If longer,
inspect pump bushing for wear. Replace pump
house.
5. Rear Band Mis-adjusted. 5. Adjust band.
6. Valve Body Filter Plugged. 6. Replace fluid and filter. If oil pan and old fluid
were full of clutch disc material and/or metal
particles, overhaul will be necessary.
7. Oil Pump Gears Worn/Damaged. 7. Remove transmission and replace oil pump.
8. Governor Circuit and Solenoid
Valve Electrical Fault.8. Test with DRBTscan tool and repair as
required.
9. Hydraulic Pressure Incorrect. 9. Perform pressure test, remove transmission
and repair as needed.
10. Reaction Shaft Seal Rings
Worn/Broken.10. Remove transmission, remove oil pump and
replace seal rings.
11. Rear Clutch/Input Shaft, Rear
Clutch Seal Rings Damaged.11. Remove and disassemble transmission and
repair as necessary.
12. Regulator Valve Stuck. 12. Clean.
13. Cooler Plugged. 13. Transfer case failure can plug cooler.
WJAUTOMATIC TRANSMISSION - 42RE 21 - 17
AUTOMATIC TRANSMISSION - 42RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
BUZZING NOISE 1. Fluid Level Low 1. Add fluid and check for leaks.
2. Shift Cable Mis-assembled. 2. Route cable away from engine and bell
housing.
3. Valve Body Mis-assembled. 3. Remove, disassemble, inspect valve body.
Reassemble correctly if necessary. Replace
assembly if valves or springs are damaged.
Check for loose bolts or screws.
4. Pump Passages Leaking. 4. Check pump for porous casting, scores on
mating surfaces and excess rotor clearance.
Repair as required. Loose pump bolts.
5. Cooling System Cooler Plugged. 5. Flow check cooler circuit. Repair as needed.
6. Overrunning Clutch Damaged. 6. Replace clutch.
SLIPS IN REVERSE
ONLY1. Fluid Level Low. 1. Add fluid and check for leaks.
2. Gearshift Linkage Mis-adjusted. 2. Adjust linkage.
3. Rear Band Mis-adjusted. 3. Adjust band.
4. Rear Band Worn. 4. Replace as required.
5. Overdrive Direct Clutch Worn. 5. Disassemble overdrive. Repair as needed.
6. Hydraulic Pressure Too Low. 6. Perform hydraulic pressure tests to determine
cause.
7. Rear Servo Leaking. 7. Air pressure check clutch-servo operation and
repair as required.
8. Band Linkage Binding. 8. Inspect and repair as required.
SLIPS IN FORWARD
DRIVE RANGES1. Fluid Level Low. 1. Add fluid and check for leaks.
2. Fluid Foaming. 2. Check for high oil level, bad pump gasket or
seals, dirt between pump halves and loose pump
bolts. Replace pump if necessary.
3. Throttle Linkage Mis-adjusted. 3. Adjust linkage.
4. Gearshift Linkage Mis-adjusted. 4. Adjust linkage.
5. Rear Clutch Worn. 5. Inspect and replace as needed.
6. Low Hydraulic Pressure Due to
Worn Pump, Incorrect Control
Pressure Adjustments, Valve Body
Warpage or Malfunction, Sticking,
Leaking Seal Rings, Clutch Seals
Leaking, Servo Leaks, Clogged
Filter or Cooler Lines.6. Perform hydraulic and air pressure tests to
determine cause.
7. Rear Clutch Malfunction,
Leaking Seals or Worn Plates.7. Air pressure check clutch-servo operation and
repair as required.
8. Overrunning Clutch Worn, Not
Holding (Slips in 1 Only).8. Replace Clutch.
SLIPS IN LOW GEAR
9D9ONLY, BUT NOT
IN MANUAL 1
POSITIONOverrunning Clutch Faulty. Replace overrunning clutch.
WJAUTOMATIC TRANSMISSION - 42RE 21 - 21
AUTOMATIC TRANSMISSION - 42RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
CLUNK NOISE FROM
DRIVELINE ON
CLOSED THROTTLE
4-3 DOWNSHIFT1. Transmission Fluid Low. 1. Add Fluid.
2. Throttle Cable Mis-adjusted. 2. Adjust cable.
3. Overdrive Clutch Select Spacer
Wrong Spacer.3. Replace overdrive piston thrust plate spacer.
3-4 UPSHIFT
OCCURS
IMMEDIATELY AFTER
2-3 SHIFT1. Overdrive Solenoid Connector or
Wiring Shorted.1.
Test connector and wiring for loose connections,
shorts or ground and repair as needed.
2. TPS Malfunction. 2. Test TPS and replace as necessary. Check with
DRBTscan tool.
3. PCM Malfunction. 3. Test PCM with DRBTscan tool and replace
controller if faulty.
4. Overdrive Solenoid Malfunction. 4. Replace solenoid.
5. Valve Body Malfunction. 5. Remove, disassemble, clean and inspect valve
body components. Make sure all valves and plugs
slide freely in bores. Polish valves with crocus
cloth if needed.
WHINE/NOISE
RELATED TO ENGINE
SPEED1. Fluid Level Low. 1. Add fluid and check for leaks.
2. Shift Cable Incorrect Routing. 2. Check shift cable for correct routing. Should not
touch engine or bell housing.
NO 3-4 UPSHIFT 1. O/D Switch In OFF Position. 1. Turn control switch to ON position.
2. Overdrive Circuit Fuse Blown. 2. Replace fuse. Determine why fuse failed and
repair as necessary (i.e., shorts or grounds in
circuit).
3. O/D Switch Wire Shorted/Open
Cut.3. Check wires/connections with 12V test lamp
and voltmeter. Repair damaged or loose
wire/connection as necessary.
4. Distance or Coolant Sensor
Malfunction.4. Check with DRBTscan tool and repair or
replace as necessary.
5. TPS Malfunction. 5. Check with DRBTscan tool and replace if
necessary.
6. Neutral Sense to PCM Wire
Shorted/Cut.6. Test switch/sensor as described in service
section and replace if necessary. Engine no start.
7. PCM Malfunction. 7. Check with DRBTscan tool and replace if
necessary.
8. Overdrive Solenoid Shorted/
Open.8. Replace solenoid if shorted or open and repair
loose or damaged wires (DRBTscan tool).
9. Solenoid Feed Orifice in Valve
Body Blocked.9. Remove, disassemble, and clean valve body
thoroughly. Check feed orifice.
10. Overdrive Clutch Failed. 10. Disassemble overdrive and repair as needed.
11. Hydraulic Pressure Low. 11. Pressure test transmission to determine
cause.
12. Valve Body Valve Stuck. 12. Repair stuck 3-4 shift valve, 3-4 timing valve.
13. O/D Piston Incorrect Spacer. 13. Remove unit, check end play and install
correct spacer.
14. Overdrive Piston Seal Failure. 14. Replace both seals.
15. O/D Check Valve/Orifice Failed. 15. Check for free movement and secure
assembly (in piston retainer). Check ball bleed
orifice.
WJAUTOMATIC TRANSMISSION - 42RE 21 - 23
AUTOMATIC TRANSMISSION - 42RE (Continued)

(26) Remove bolts holding the upper transmission
bending braces to the torque converter housing and
the overdrive unit (Fig. 20).
(27) Remove all remaining converter housing bolts.
(28) Carefully work transmission and torque con-
verter assembly rearward off engine block dowels.
(29) Hold torque converter in place during trans-
mission removal.
(30) Lower transmission and remove assembly
from under the vehicle.
(31) To remove torque converter, 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.
21).
(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 indica-
tor.
(e) Move the input shaft in and out. Record the
maximum travel for assembly reference.
(4) Remove shift and throttle levers from valve
body manual lever shaft.
(5) Place transmission in horizontal position.
(6) Remove transmission oil pan and gasket.
(7) Remove filter from valve body (Fig. 22). Keep
filter screws separate from other valve body screws.
Filter screws are longer and should be kept with fil-
ter.
(8) Remove park/neutral position switch.
(9) Remove hex head bolts attaching valve body to
transmission case (Fig. 23). A total of 10 bolts are
used. Note different bolt lengths for assembly refer-
ence.
Fig. 19 Remove NV242 Transfer Case
1 - NV242 TRANSFER CASE
Fig. 20 Remove Upper Transmission Bending
Braces
1 - TRANSMISSION BENDING BRACES
Fig. 21 Checking Input Shaft End Play
1 - TOOL 8266-8
2 - TOOL 8266-6
3 - TOOL C-3339
WJAUTOMATIC TRANSMISSION - 42RE 21 - 29
AUTOMATIC TRANSMISSION - 42RE (Continued)

(32) Install valve body as follows:
(a) Align and carefully insert park rod into pawl.
Rod will make click noise as it enters pawl. Move
rod slightly to check engagement.
(b) Align and seat valve body on case. Be sure
manual lever shaft and overdrive connector are
fully seated in case. Also be sure valve body wiring
is not pinched or kinked.
(c) Install and start all valve body attaching
bolts by hand. Then tighten bolts evenly, in a diag-
onal pattern to 12 N´m (105 in. lbs.) torque. Do not
overtighten valve body bolts. This could result in
distortion and cross leakage after installation.
CAUTION: It is possible for the park rod to displace
into a cavity just above the pawl sprag during
installation. Make sure the rod is actually engaged
in the pawl and has not displaced into the cavity.
(33) Install new filter on valve body. Tighten filter
screws to 4 N´m (35 in. lbs.).
(34) Adjust front and rear bands.
(35) Install seal on park/neutral position switch.
Then install and tighten switch to 34 N´m (25 ft.
lbs.).
(36) Install magnet in oil pan. Magnet goes on
small protrusion at corner of pan.
(37) Position new oil pan gasket on case and
install oil pan. Tighten pan bolts to 17 N´m (13 ft.
lbs.).
(38) Install new valve body manual shaft seal in
case (Fig. 60). Lubricate seal lip and manual shaft
with petroleum jelly. Start seal over shaft and into
case. Seat seal with 15/16 inch, deep well socket.
(39) Install throttle valve and shift selector levers
on valve body manual lever shaft.INSTALLATION
(1) Check torque converter hub and hub drive
notches for sharp edges burrs, scratches, or nicks.
Polish the hub and notches with 320/400 grit paper
and crocus cloth if necessary. The hub must be
smooth to avoid damaging pump seal during installa-
tion.
(2) Lubricate oil pump seal lip with transmission
fluid.
(3) Align converter and oil pump.
(4) Carefully insert converter in oil pump. Then
rotate converter back and forth until fully seated in
pump gears.
(5) Check converter seating with steel scale and
straightedge (Fig. 61). Surface of converter lugs
should be 1/2 in. to rear of straightedge when con-
verter is fully seated.
(6) Temporarily secure converter with C-clamp.
(7) Position transmission on jack and secure it
with chains.
(8) Check condition of converter driveplate.
Replace the plate if cracked, distorted or damaged.
Also be sure transmission dowel pins are seated in
engine block and protrude far enough to hold trans-
mission in alignment.
(9) Apply a light coating of MopartHigh Temp
grease to the torque converter hub pocket in the rear
of the crankshaft
(10) Raise transmission and align converter with
drive plate and converter housing with engine block.
Fig. 60 Installing Manual Lever Shaft Seal
1 - 15/1688SOCKET
2 - SEAL
Fig. 61 Checking Torque Converter Seating - Typical
1 - SCALE
2 - STRAIGHTEDGE
WJAUTOMATIC TRANSMISSION - 42RE 21 - 41
AUTOMATIC TRANSMISSION - 42RE (Continued)

(1) A result of restricted fluid flow through the
main and/or auxiliary cooler. This condition is usu-
ally the result of a faulty or improperly installed
drainback valve, a damaged main cooler, or severe
restrictions in the coolers and lines caused by debris
or kinked lines.
(2) Heavy duty operation with a vehicle not prop-
erly equipped for this type of operation. Trailer tow-
ing or similar high load operation will overheat the
transmission fluid if the vehicle is improperly
equipped. Such vehicles should have an auxiliary
transmission fluid cooler, a heavy duty cooling sys-
tem, and the engine/axle ratio combination needed to
handle heavy loads.
DIAGNOSIS AND TESTING - FLUID
CONTAMINATION
Transmission fluid contamination is generally a
result of:
²adding incorrect fluid
²failure to clean dipstick and fill tube when
checking level
²engine coolant entering the fluid
²internal failure that generates debris
²overheat that generates sludge (fluid break-
down)
²failure to reverse flush cooler and lines after
repair
²failure to replace contaminated converter after
repair
The use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failure
due to fluid breakdown and sludge formation. Avoid
this condition by using recommended fluids only.
The dipstick cap and fill tube should be wiped
clean before checking fluid level. Dirt, grease and
other foreign material on the cap and tube could fall
into the tube if not removed beforehand. Take the
time to wipe the cap and tube clean before withdraw-
ing the dipstick.
Engine coolant in the transmission fluid is gener-
ally caused by a cooler malfunction. The only remedy
is to replace the radiator as the cooler in the radiator
is not a serviceable part. If coolant has circulated
through the transmission, an overhaul is necessary.
The transmission cooler and lines should be
reverse flushed whenever a malfunction generates
sludge and/or debris. The torque converter should
also be replaced at the same time.
Failure to flush the cooler and lines will result in
recontamination. Flushing applies to auxiliary coolers
as well. The torque converter should also be replaced
whenever a failure generates sludge and debris. This
is necessary because normal converter flushing proce-
dures will not remove all contaminants.
STANDARD PROCEDURE
STANDARD PROCEDURE - FLUID LEVEL
CHECK
Low fluid level can cause a variety of conditions
because it allows the pump to take in air along with
the fluid. As in any hydraulic system, air bubbles
make the fluid spongy, therefore, pressures will be
low and build up slowly.
Improper filling can also raise the fluid level too
high. When the transmssion has too much fluid, the
geartrain churns up foam and cause the same condi-
tions which occur with a low fluid level.
In either case, air bubbles can cause overheating
and/or fluid oxidation, and varnishing. This can
interfere with normal valve, clutch, and accumulator
operation. Foaming can also result in fluid escaping
from the transmission vent where it may be mis-
taken for a leak.
After the fluid has been checked, seat the dipstick
fully to seal out water and dirt.
The transmission has a dipstick to check oil level.
It is located on the right side of the engine. Be sure
to wipe all dirt from dipstick handle before removing.
Fluid level is checked with the engine running at
curb idle speed, the transmission in NEUTRAL and
the transmission fluid at normal operating tempera-
ture.The engine should be running at idle
speed for at least one minute, with the vehicle
on level ground.
The transmission fluid level can be checked two
ways.
PROCEDURE ONE
(1) Transmission fluid must be at normal operat-
ing temperature for accurate fluid level check. Drive
vehicle if necessary to bring fluid temperature up to
normal hot operating temperature of 82ÉC (180ÉF).
(2) Position vehicle on level surface.
(3) Start and run engine at curb idle speed.
(4) Apply parking brakes.
(5) Shift transmission momentarily into all gear
ranges. Then shift transmission back to NEUTRAL.
(6) Clean top of filler tube and dipstick to keep
dirt from entering tube.
(7) Remove dipstick (Fig. 87) and check fluid level
as follows:
(a) Correct acceptable level is in crosshatch area.
(b) Correct maximum level is to MAX arrow
mark.
(c) Incorrect level is at or below MIN line.
(d) If fluid is low, add only enough MopartAT F
+4, type 9602, to restore correct level. Do not over-
fill.
21 - 70 AUTOMATIC TRANSMISSION - 42REWJ
FLUID AND FILTER (Continued)

PROCEDURE TWO
(1) Start engine and apply parking brake.
(2) Shift the transmission into DRIVE for approxi-
mately 2 seconds.
(3) Shift the transmission into REVERSE for
approximately 2 seconds.
(4) Shift the transmission into PARK.
(5) Hook up DRBtscan tool and select engine.
(6) Select sensors.
(7) Read the transmission temperature value.
(8) Compare the fluid temperature value with the
figure. (Fig. 88)
(9) Adjust transmission fluid level shown on the
dipstick according to the figure.NOTE: After adding any fluid to the transmission,
wait a minimum of 2 minutes for the oil to fully
drain from the fill tube into the transmission before
rechecking the fluid level.
(10) Check transmission for leaks.
STANDARD PROCEDURE - FLUID AND FILTER
REPLACEMENT
For proper service intervals (Refer to LUBRICA-
TION & MAINTENANCE/MAINTENANCE SCHED-
ULES - DESCRIPTION). The service fluid fill after a
filter change is approximately 3.8 liters (4.0 quarts).
REMOVAL
(1) Hoist and support vehicle on safety stands.
(2) Place a large diameter shallow drain pan
beneath the transmission pan.
(3) Remove bolts holding front and sides of pan to
transmission (Fig. 89).
(4) Loosen bolts holding rear of pan to transmis-
sion.
(5) Slowly separate front of pan and gasket away
from transmission allowing the fluid to drain into
drain pan.
(6) Hold up pan and remove remaining bolt hold-
ing pan to transmission.
Fig. 88 42/44RE Fluid Fill Graph
Fig. 87 Dipstick Fluid Level Marks - Typical
1 - DIPSTICK
2 - MAXIMUM CORRECT FLUID LEVEL
3 - ACCEPTABLE FLUID LEVEL
WJAUTOMATIC TRANSMISSION - 42RE 21 - 71
FLUID AND FILTER (Continued)