Jeep Cherokee 2000, Service Manual

Page: 1039 / 1528

(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
This test checks pressure regulation and condition
of the clutch circuits. Use both pressure Test Gauges
C-3292 and C-3293-SP for this test.
(1) Connect test gauges to accumulator and front
servo ports (Fig. 57) and (Fig. 58). Use either test
gauge at the two ports.
(2) Start and run engine at 1600 rpm for this test.
(3) Move selector lever to D range. This is two
detents rearward from full forward position.
(4) Read pressures on both gauges as transmission
throttle lever is moved from full forward to full rear-
ward position.
(5) Line pressure should be 54-60 psi (372-414
kPa) with throttle lever forward and gradually
increase as lever is moved rearward.
(6) Front servo is pressurized only in D range and
should be same as line pressure within 3 psi (21 kPa)
up to downshift point.
Test Four - Transmission In Reverse
This test checks pump output, pressure regulation
and the front clutch and rear servo circuits. Use 300
psi Test Gauge C-3293-SP for this test.
(1) Connect 300 psi gauge to rear servo port (Fig.
57) and (Fig. 58).
(2) Start and run engine at 1600 rpm for test.
(3) Move valve body selector lever four detents
rearward from the full forward position. This is
Reverse range.
(4) Move throttle lever all way forward then all
way rearward and note gauge readings.
(5) Pressure should be 145 - 175 psi (1000-1207
kPa) with lever forward and increase to 230 - 280 psi
(1586-1931 kPa) as lever is moved rearward.
Test Five - Governor Pressure
This test checks governor operation by measuring
governor pressure response to changes in engine
speed. It is usually not necessary to check governor
operation unless shift speeds are incorrect or if the
transmission will not downshift.
(1) Connect 100 psi Test Gauge C-3292 to governor
pressure port (Fig. 57) and (Fig. 58).
(2) Move shift lever to D range.
(3) Start and run engine at curb idle speed and
note pressure. At idle and with vehicle stopped, pres-
sure should be zero to 1.5 psi maximum. If pressure
exceeds this figure, governor valve or weights are
sticking open.
(4) Slowly increase engine speed and observe
speedometer and pressure test gauge. Governor pres-
sure should increase in proportion to vehicle speed.
(5) Pressure rise should be smooth and drop back
to 0 to 1.5 psi when wheels stop rotating.
(6) Compare results of pressure tests with analysis
charts (Fig. 60).
AIR TESTING TRANSMISSION CLUTCH AND
BAND OPERATION
Air-pressure testing can be used to check transmis-
sion front/rear clutch and band operation. The test
can be conducted with the transmission either in the
vehicle or on the work bench, as a final check, after
overhaul.
Air-pressure testing requires that the oil pan and
valve body be removed from the transmission. The
servo and clutch apply passages are shown (Fig. 61).
TEST CONDITION INDICATION
Line pressure OK during
any one test Pump and regulator valve
OK
Line pressure OK in R
but low in D, 2, 1 Leakage in rear clutch
area (servo, clutch seals,
governor support seal
rings on park gear)
Pressure OK in 1, 2 but
low in D3 and R Leakage in front clutch
area (servo, clutch seals,
retainer bore, pump seal
rings)
Pressure OK in 2 but low
in R and 1 Leakage in rear servo
Front servo pressure in 2 Leakage in servo (broken
servo ring or cracked
servo piston)
Pressure low in all
positions Clogged filter, stuck
pressure regulator valve,
worn or defective pump
Governor pressure too
high at idle speed Governor valve sticking
open
Governor pressure low at
all mph figures Governor valve sticking
closed
Lubrication pressure low
at all throttle positions Clogged drainback valve,
oil cooler or lines, seal
rings leaking, output shaft
plugged with devris, worn
bushings in pump or
clutch retainer
Fig. 60 Pressure Test Analysis
XJ
AUTOMATIC TRANSMISSION—30RH 21 - 131
DIAGNOSIS AND TESTING (Continued)