Chrysler New Yorker. Manual — part 283
SENSORS
There are three pressure switches which identify
solenoid application. The pressure switches are incor-
porated in an assembly with the solenoids. Two speed
sensors read input (torque converter turbine) and
output (parking sprag) speeds. There is also a Trans-
mission Range Sensor (TRS) which senses manual
valve position.
Engine speed, throttle position, temperature, etc., are
also observed. Some of these signals are read directly
from the engine control sensors; others are read from a
multiplex circuit with the engine controller.
ADAPTIVE CONTROLS
These controls function by reading the input and
output speeds over 140 times a second and respond-
ing to each new reading. This provides the friction
element control needed to make smooth clutch-to-
clutch shifts for all gear changes without the use of
overrunning clutches. As with most automatic tran-
saxles, all shifts involve releasing one element and
applying a different element. In simplified terms, the
upshift logic allows the releasing element to slip
backwards slightly to ensure that it does not have
excess capacity; the apply element is filled until it
begins to make the speed change to the higher gear;
its apply pressure is then controlled to maintain the
desired rate of speed change until the shift is com-
plete. The key to providing excellent shift quality is
precision; for example, as mentioned, the release ele-
ment for upshifts is allowed to slip backwards
slightly; the amount of that slip is typically less than
a total of 20 degrees. To achieve that precision, the
transmission control module learns the characteris-
tics of the particular transaxle that it is controlling.
It learns:
• The release rate of the releasing element.
• The apply time of the applying element.
• The rate the apply element builds pressure.
This method achieves more precision than would be
possible with exacting tolerances. It can also adapt to
any changes that occur with age or environment.
For kickdown shifts, the control logic allows the
releasing element to slip. Then controls the rate at
which the input (and engine) accelerate. When the
lower gear speed is achieved, the releasing element
reapplies to maintain that speed until the apply ele-
ment is filled. This provides quick response and a
smooth torque exchange since the release element
can control the rate of torque increase. This control
can make any powertrain feel more responsive with-
out increasing harshness.
Adaptive controls respond to input speed changes.
They compensate for changes in engine or friction
element torque. Thus providing consistent shift qual-
ity for the life of the transaxle.
DIAGNOSTICS
These
controls
also
provide
comprehensive,
on-board
transaxle
diagnostics.
The
information
available can aid in transaxle diagnosis. For exam-
ple, apply element buildup rate indicates solenoid
performance. Also included are self-diagnostic func-
tions which allow the technician to test the electronic
controls. The transmission control module monitors
its critical functions, records any malfunctions, and
the number of engine starts since the last malfunc-
tion. The technician can use this information in the
event of a customer complaint. Refer to the 42LE
Transaxle Diagnostic Procedure Manual for specifics.
TRANSMISSION CONTROL MODULE
The transmission control module is located in the
engine compartment between the left front fender
and the battery. It is held in place by four mounting
screws. The battery must be moved to gain access to
the transmission control module.
NOTE: If the transmission control module has been
replaced, refer to Quick Learn Procedure. This pro-
gram will allow the transmission control module to
learn the characteristics of the vehicle.
TRANSMISSION CONTROL RELAY
The transmission control module controls power to
the solenoid pack through the transmission control
relay. The relay is located in the power distribution
center on the left side of the engine compartment.
Refer to the 42LE Transaxle Diagnostic Procedures
Manual for test procedures.
SOLENOID ASSEMBLY
The transaxle solenoid pack is located on the top
side of the valve body. The valve body must be
removed from the transaxle in order to service the
solenoid pack.
The solenoid pack contains four solenoids. If any
one of the solenoids fail, all of the solenoids must be
replaced. There are no serviceable parts for the sole-
noid pack.
Refer to the 42LE Transaxle Diagnostic Procedures
Manual for diagnostic test procedures.
SHIFTER/IGNITION INTERLOCK
The ignition interlock system connects the auto-
matic transmission shifter and the lock system. With
the ignition key in the LOCK or ACCESSORY posi-
tion, the interlock system holds the transmission
shifter in park. When the key is in the OFF or RUN
position the shifter unlocks and can be moved to any
position. Also, if the shifter is not in PARK, the sys-
tem prevents the operator from turning the ignition
switch to the LOCK or ACCESSORY positions.
300M
TRANSAXLE
21 - 5
DESCRIPTION AND OPERATION (Continued)
NOTE: If the vehicle has column shift, install a new
interlock cassette (column shift) when replacing the
ignition lock cylinder. Adjust the system after
replacing the cassette.
NOTE: If the vehicle has floor shift, adjust the inter-
lock cable after replacing the lock cylinder.
TRANSMISSION RANGE SENSOR
The Transmission Range Sensor (TRS) interprets
the position of the manual valve. This information is
sent to the transmission control module. Also the
TRS provides for Park/Neutral only starter operation
and back-up lamp operation.
The TRS connector extends outside the transaxle
on the left side, next to the fill tube. The TRS is
mounted to the top of the valve body. The TRS and
valve body must be removed from the transaxle as an
assembly.
Refer to the 42LE Transaxle Diagnostic Procedures
Manual for TRS diagnostic test procedures.
TRANSMISSION TEMPERATURE SENSOR
Located within the Transmission Range Sensor is a
transmission temperature sensor. This sensor is used
to measure the transmission fluid sump temperature.
The transmission temperature sensor is serviced
with the TRS as a unit.
AUTOSTICK
OPERATION
Autostick is a driver–interactive transaxle feature
that offers manual gear shifting capability. When the
shifter is moved into the Autostick position, the tran-
saxle remains in whatever gear it was using before
Autostick was activated. Moving the shifter to the
left (towards the driver) causes a downshift and mov-
ing to the right (towards the passenger) causes an
upshift. The instrument cluster will illuminate the
selected gear. The vehicle can be launched in 1st,
2nd, or 3rd gear while in the Autostick mode. The
speed control is operable in 3rd and 4th gear Auto-
stick mode. Speed control will be deactivated if the
transaxle is shifted to 2nd gear. Shifting into OD
position cancels the Autostick mode, and the tran-
saxle resumes the OD shift schedule.
AUTOMATIC OVERRIDES
For safety, durability, and driveability, some shifts
are executed automatically or prevented.
SHIFT POSITION INDICATOR
The shifter position indicator is located in the
instrument cluster. The shifter position indicator out-
lines with a box the gear position the transaxle man-
ual valve lever is in.
The Transmission Range Sensor (located on the
valve body) sends a signal to the TCM on the posi-
tion of the transaxle manual valve lever. The TCM
receives the switch signal and processes the data.
The TCM sends the Shift Lever Position (SLP) infor-
mation to the Cluster via the J1850 bus. The Cluster
then illuminates the appropriate shifter position indi-
cator.
To replace the shifter position indicator, refer to
Group 8E, Instrument Panel And Gauges.
DIAGNOSIS AND TESTING
42LE GENERAL DIAGNOSIS
CAUTION: Before attempting any repair on the
42LE Four Speed Automatic Transaxle, always
check for proper shift linkage adjustment. Also
check for diagnostic trouble codes with the DRB
scan tool and the 42LE Transaxle Diagnostic Proce-
dure Manual.
42LE automatic transaxle malfunctions may be
caused by these general conditions:
• Poor engine performance
• Improper adjustments
• Hydraulic malfunctions
• Mechanical malfunctions
• Electronic malfunctions
AUTOMATIC SHIFTS WILL OCCUR UNDER
THE FOLLOWING CONDITIONS
TYPE OF SHIFT
APPROXIMATE SPEED
4-3 coast downshift
13 mph
3-2 coast downshift
9 mph
2-1 coast downshift
5 mph
1-2 upshift
6300 engine rpm
2-3 upshift
6300 engine rpm
4-3 kickdown shift
13-47 mph w/sufficient
throttle
MANUAL SHIFTS ARE NOT PERMITTED
UNDER THE FOLLOWING CONDITIONS
TYPE OF SHIFT
APPROXIMATE SPEED
3-4 upshift
Below 15 mph
3-2 downshift
Above 74 mph @ closed
throttle or 70 mph otherwise
2-1 downshift
Above 41 mph @ closed
throttle or 38 mph otherwise
21 - 6
TRANSAXLE
300M
DESCRIPTION AND OPERATION (Continued)
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 transaxle 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 linkage 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.
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 transaxle should be oper-
ated 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
transaxle cleaning.
An engine miss could be attributed to a cracked
drive plate. A cracked drive plate could cause the
camshaft position sensor and crankshaft position sen-
sor signals to be out of synchronization. This could
cause a no-start condition.
A slipping clutch will set a DTC 50–54 only and
can be determined by operating the transaxle in all
selector positions. Then comparing which internal
units are applied in those positions. The Elements in
Use Chart provides a basis for road test analysis.
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.
HYDRAULIC PRESSURE TESTS
Pressure testing is a very important step in the
diagnostic procedure. These tests usually reveal the
cause of most transaxle 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 front wheels to turn, and position
tachometer so it can be read.
Using special adapters (L-4559), attach 300 psi
gauges to ports required for test being conducted.
Test port locations are shown in (Fig. 6).
TEST ONE-SELECTOR IN L
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 L 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 3
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 3 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 2A–SELECTOR IN OD
NOTE: This
test
checks
the
underdrive
clutch
hydraulic circuit as well as the shift schedule.
(1) Attach gauge to the UD clutch tap.
(2) Move selector lever to the OD position.
(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
TCM is at fault.
300M
TRANSAXLE
21 - 7
DIAGNOSIS AND TESTING (Continued)
TEST THREE-SELECTOR IN OD
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 OD 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 3 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 OD
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 OD position.
(3) Allow vehicle front wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 30 mph.
(4) The 2/4 clutch pressure should read 75 to 95
psi.
TEST FIVE-SELECTOR IN OD
NOTE: These tests checks the torque converter
clutch hydraulic circuit.
(1) Attach gauge to the torque converter clutch off
pressure tap.
(2) Move selector lever to the OD position.
(3) Allow vehicle wheels to turn and increase
throttle opening to achieve an indicated vehicle speed
of 50 mph.
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.
Fig. 5 ELEMENTS IN USE AT EACH POSITION OF THE SELECTOR LEVER
Fig. 6 Pressure Taps
21 - 8
TRANSAXLE
300M
DIAGNOSIS AND TESTING (Continued)
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