Jeep Wrangler TJ. Manual — part 489
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - AUTOMATIC
TRANSMISSION
CAUTION: Before attempting any repair on the
42RLE Four Speed Automatic Transmission, always
check for proper shift cable adjustment. Also check
for diagnostic trouble codes with the DRB
T
scan
tool and the 42RLE Transmission Diagnostic Proce-
dure Manual.
42RLE automatic transmission malfunctions may
be caused by these general conditions:
• Poor engine performance
• Improper adjustments
• Hydraulic malfunctions
• Mechanical malfunctions
• Electronic malfunctions
When diagnosing a problem always begin with
recording the complaint. The complaint should be
defined as specific as possible. Include the following
checks:
• Temperature at occurrence (cold, hot, both)
• Dynamic conditions (acceleration, deceleration,
upshift, cornering)
• Elements in use when condition occurs (what
gear is transmission in during condition)
• Road and weather conditions
• Any other useful diagnostic information.
After noting all conditions, check the easily acces-
sible variables:
• Fluid level and condition
• Shift cable adjustment
• Diagnostic trouble code inspection
Then perform a road test to determine if the prob-
lem has been corrected or that more diagnosis is nec-
essary. If the problem exists after the preliminary
tests and corrections are completed, hydraulic pres-
sure checks should be performed.
DIAGNOSIS AND TESTING - ROAD TEST
Prior to performing a road test, verify that the
fluid level, fluid condition, and linkage adjustment
have been approved.
During the road test, the transmission should be
operated in each position to check for slipping and
any variation in shifting.
If the vehicle operates properly at highway speeds,
but has poor acceleration, the converter stator over-
running clutch may be slipping. If acceleration is nor-
mal, but high throttle opening is needed to maintain
highway speeds, the converter stator clutch may
have seized. Both of these stator defects require
replacement of the torque converter and thorough
transmission cleaning.
Slipping clutches can be isolated by comparing the
“Elements in Use” chart with clutch operation
encountered on a road test. This chart identifies
which clutches are applied at each position of the
selector lever.
A slipping clutch may also set a DTC and can be
determined by operating the transmission in all
selector positions.
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AUTOMATIC TRANSMISSION - 42RLE
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AUTOMATIC TRANSMISSION - 42RLE (Continued)
ELEMENTS IN USE AT EACH POSITION OF SELECTOR LEVER
Shift Lever
Position
INPUT CLUTCHES
HOLDING CLUTCHES
Underdrive
Overdrive
Reverse
2/4
Low/Reverse
P - PARK
X
R - REVERSE
X
X
N - NEUTRAL
X
OD -
OVERDRIVE
First
X
X
Second
X
X
Direct
X
X
Overdrive
X
X
D - DRIVE*
First
X
X
Second
X
X
Direct
X
X
L - LOW*
First
X
X
Second
X
X
Direct
X
X
* Vehicle upshift and downshift speeds are increased when in these selector positions.
The process of elimination can be used to detect
any unit which slips and to confirm proper operation
of good units. Road test analysis can diagnose slip-
ping units, but the cause of the malfunction cannot
be determined. Practically any condition can be
caused by leaking hydraulic circuits or sticking
valves.
DIAGNOSIS AND TESTING - HYDRAULIC
PRESSURE TESTS
Pressure testing is a very important step in the
diagnostic procedure. These tests usually reveal the
cause of most transmission problems.
Before performing pressure tests, be certain that
fluid level and condition, and shift cable adjustments
have been checked and approved. Fluid must be at
operating temperature (150 to 200 degrees F.).
Install an engine tachometer, raise vehicle on hoist
which allows the wheels to turn, and position
tachometer so it can be read.
Using special adapters L-4559, attach 300 psi
gauge(s) C-3293SP to the port(s) required for test
being conducted.
Test port locations are shown in the Pressure Taps
graphic. (Fig. 8)
Fig. 8 Pressure Taps
1 - TORQUE CONVERTER CLUTCH OFF
2 - REVERSE
3 - LOW/REVERSE
4 - 2/4
5 - UNDERDRIVE
6 - TORQUE CONVERTER CLUTCH ON
7 - OVERDRIVE
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AUTOMATIC TRANSMISSION - 42RLE
21 - 47
AUTOMATIC TRANSMISSION - 42RLE (Continued)
TEST ONE - SELECTOR IN MANUAL 1 (1st Gear)
NOTE: This test checks pump output, pressure reg-
ulation and condition of the low/reverse clutch
hydraulic circuit and shift schedule.
(1) Attach pressure gauge to the low/reverse clutch
tap.
(2) Move selector lever to the MANUAL 1 position.
(3) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
to 20 mph.
(4) Low/reverse clutch pressure should read 115 to
145 psi.
TEST TWO - SELECTOR IN MANUAL 2 (Second
Gear)
NOTE: This test checks the underdrive clutch
hydraulic circuit as well as the shift schedule.
(1) Attach gauge to the underdrive clutch tap.
(2) Move selector lever to the MANUAL 2 position.
(3) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 30 mph.
(4) In second gear the underdrive clutch pressure
should read 110 to 145 psi.
TEST TWO A - SELECTOR IN DRIVE (OD ON -
Fourth Gear)
NOTE: This test checks the underdrive clutch
hydraulic circuit as well as the shift schedule.
(1) Attach gauge to the underdrive clutch tap.
(2) Move selector lever to the DRIVE position.
Verfy that the OD switch is ON.
(3) Allow wheels to rotate freely and increase
throttle opening to achieve an indicated speed of 40
mph.
(4) Underdrive clutch pressure should read below
5 psi. If not, than either the solenoid assembly or
controller is at fault.
TEST THREE - SELECTOR IN DRIVE (OD OFF -
Third and Second Gear)
NOTE:
This
test
checks
the
overdrive
clutch
hydraulic circuit as well as the shift schedule.
(1) Attach gauge to the overdrive clutch tap.
(2) Move selector lever to the DRIVE position.
(3) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 20 mph.
(4) Overdrive clutch pressure should read 74 to 95
psi.
(5) Move selector lever to the DRIVE position and
increase indicated vehicle speed to 30 mph.
(6) The vehicle should be in second gear and over-
drive clutch pressure should be less than 5 psi.
TEST FOUR - SELECTOR IN DRIVE (OD ON -
Fourth Gear)
NOTE: This test checks the 2/4 clutch hydraulic cir-
cuit.
(1) Attach gauge to the 2/4 clutch tap.
(2) Move selector lever to the DRIVE position.
(3) Allow vehicle front wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 30 mph. Vehicle should be in fourth gear.
(4) The 2/4 clutch pressure should read 75 to 95
psi.
TEST FIVE-SELECTOR IN DRIVE (OD ON - Fourth
Gear, CC on)
NOTE: These tests check the torque converter
clutch hydraulic circuit.
(1) Attach gauge to the torque converter clutch off
pressure tap.
(2) Move selector lever to the DRIVE position.
(3) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 50 mph. Vehicle should be in 4th gear, CC on.
CAUTION: Both wheels must turn at the same
speed.
(4) Torque converter clutch off pressure should be
less than 5 psi.
(5) Now attach the gauge to the torque converter
clutch on pressure tap.
(6) Move selector to the OD position.
(7) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 50 mph.
(8) Verify the torque converter clutch is applied
mode using the RPM display of the DRB scan tool.
(9) Torque converter clutch on pressure should be
60-90 psi.
TEST SIX-SELECTOR IN REVERSE
NOTE: This test checks the reverse clutch hydraulic
circuit.
(1) Attach gauge to the reverse and low/reverse
clutch tap.
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AUTOMATIC TRANSMISSION - 42RLE
TJ
AUTOMATIC TRANSMISSION - 42RLE (Continued)
(2) Move selector lever to the REVERSE position.
(3) Read reverse clutch pressure with output sta-
tionary (foot on brake) and throttle opened to achieve
1500 rpm.
(4) Reverse and low/reverse clutch pressure should
read 165 to 235 psi.
TEST RESULT INDICATIONS
(1) If proper line pressure is found in any one test,
the pump and pressure regulator are working prop-
erly.
(2) Low pressure in all positions indicates a defec-
tive pump, a clogged filter, or a stuck pressure regu-
lator valve.
(3) Clutch circuit leaks are indicated if pressures
do not fall within the specified pressure range.
(4) If the overdrive clutch pressure is greater than
5 psi in Step 6 of Test Three, a worn reaction shaft
seal ring or a defective solenoid assembly is indi-
cated.
(5) If the underdrive clutch pressure is greater
than 5 psi in Step 4 of Test Two-A, a defective sole-
noid/pressure switch assembly or controller is the
cause.
ALL PRESSURE SPECIFICATIONS ARE PSI (ON HOIST, WITH WHEELS FREE TO TURN)
Gear Selector
Position
Actual Gear
PRESSURE TAPS
Under-
drive
Clutch
Over-
drive
Clutch
Reverse
Clutch
Torque
Converter
Clutch
Off
Torque
Converter
Clutch
On
2/4
Clutch
Low/
Reverse
Clutch
PARK - 0 mph *
PARK
0-2
0-5
0-2
60-110
45-100
0-2
115-145
REVERSE - 0 mph *
REVERSE
0-2
0-7
165-235
50-100
35-85
0-2
165-235
NEUTRAL - 0 mph *
NEUTRAL
0-2
0-5
0-2
60-110
45-100
0-2
115-145
Low - 20 mph #
FIRST
110-145
0-5
0-2
60-110
45-100
0-2
115-145
Third - 30 mph #
SECOND
110-145
0-5
0-2
60-110
45-100
115-
145
0-2
Third - 45 mph #
DIRECT
75-95
75-95
0-2
60-90
45-80
0-2
0-2
OD - 30 mph #
OVERDRIVE
0-2
75-95
0-2
60-90
45-80
75-95
0-2
OD - 50 mph #
OVERDRIVE
WITH TCC
0-2
75-95
0-2
0-5
60-95
75-95
0-2
* Engine Speed at 1500 rpm
# CAUTION: Both wheels must be turning at same speed.
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AUTOMATIC TRANSMISSION - 42RLE
21 - 49
AUTOMATIC TRANSMISSION - 42RLE (Continued)
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