Diagnosis And Testing - Hydraulic Pressure Tests - Chrysler 300M Service Manual

21 - 6 TRANSAXLE
42LE AUTOMATIC TRANSAXLE (Continued)
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 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
gauge(s) (C-3293SP) to port(s) required for test being
conducted.
Test port locations are shown in (Fig. 4).
Fig. 4 Pressure Taps
1 - TORQUE CONVERTER CLUTCH OFF
2 - TURBINE SPEED SENSOR
3 - OUTPUT SPEED SENSOR
4 - LOW/REVERSE
5 - REVERSE
6 - UNDERDRIVE
7 - TORQUE CONVERTER CLUTCH ON
8 - OVERDRIVE
TEST ONE-SELECTOR IN L (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 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 DRIVE (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 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 TWO A–SELECTOR IN OD (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 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
controller is at fault.
TEST THREE-SELECTOR IN OVERDRIVE (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 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 (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 OD 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.
LH