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AUTOMATIC TRANSMISSION
21 - 49
DIAGNOSIS AND T E S T P R O C E D U R E S
INDEX
Page
Air Pressure Test . . . . . . . . .
f
. . . . .
53
Analyzing the Road Test
50
Checking Fluid Level And Condition
. . . . . . . . . . . 49
Converter Housing Fluid Leak Diagnosis . . . . . . . . 54
Converter Stall Test
52
Diagnosis Guides And Charts . . . . . . . . . . . . . . . . 57
Gearshift Linkage
50
GENERAL INFORMATION
A u t o m a t i c transmission problems can be a result of
poor engine performance, incorrect fluid level, incor-
rect linkage adjustment, band o r h y d r a u l i c control
pressure adjustments, h y d r a u l i c system malfunctions
or mechanical component malfunctions.
Begin diagnosis by checking t h e easily
accessible
items such as fluid lever and condition and linkage
adjustments. A road test w i l l determine i f f u r t h e r d i -
agnosis is necessary.
Procedures o u t l i n e d i n t h i s section should be per-
formed i n t h e f o l l o w i n g sequence t o realize t h e most
accurate results:
• P r e l i m i n a r y diagnosis
• F l u i d Level a n d condition
• L i n k a g e A d j u s t m e n t
• Road test
• S t a l l test
• H y d r a u l i c pressure test
• A i r pressure tests
• Leak Tests
• Analyze test results and consult diagnosis charts
PRELIMINARY DIAGNOSIS
Two basic procedures are required. One procedure
for vehicles t h a t are driveable a n d a n alternate pro-
cedure for disabled vehicles ( w i l l n o t back u p or
move forward).
Vehicle Is Driveable
(1) Check fluid level and condition.
(2) Adjust t h r o t t l e and gearshift linkage i f com-
p l a i n t was based on delayed, erratic, or h a r s h shifts.
(3) Road test and note transmission operating char-
acteristics.
(4) Perform s t a l l test i f complaint is based on slug-
gish acceleration or i f abnormal t h r o t t l e opening is
needed to m a i n t a i n n o r m a l spieeds w i t h a properly
tuned engine.
(5) Perform h y d r a u l i c pressure tests.
(6) Perform a i r pressure test t o check clutch-band
Operation.
Page
General Information
49
Hydraulic Pressure Test
.
51
Lockup Torque Converter Diagnosis Chart
. . . . . . 60
Preliminary Diagnosis . . . . . . . . . . . . . . . . . . . . . . 49
Road Test
50
Throttle Valve Linkage
50
Transmission Diagnosis Chart
59
Vehicle Is Disabled
(1) Check fluid level and condition.
(2) Check for broken, disconnected t h r o t t l e l i n k a g e .
(3) Check for cracked, l e a k i n g cooler lines, or loose,
missing pressure port plugs.
(4) Raise vehicle, s t a r t engine, shift transmission
i n t o gear and note following:
(a) I f propeller shafts t u r n b u t wheels do not,
problem is w i t h differential or axle shafts.
(b) I f propeller shafts do not t u r n and t r a n s m i s -
sion i s noisy, stop engine. Remove o i l pan, a n d
check for debris. I f p a n is clear, remove t r a n s m i s -
sion and check for damaged drive plate, converter,
o i l p u m p or i n p u t shaft.
(c) I f propeller shafts do not t u r n and t r a n s m i s -
sion is not noisy, perform h y d r a u l i c pressure test t o
determine i f problem is a h y d r a u l i c or mechanical.
CHECKING FLUID LEVEL AND CONDITION
(1) Place t h e vehicle on a level surface. This is i m -
p o r t a n t for a n accurate reading.
(2) To avoid false readings, w h i c h could produce
under or over fill condition, do not check level u n t i l
fluid
is a t n o r m a l operating temperature of 180°F.
(3) Shift transmission i n t o N e u t r a l .
(4) A p p l y p a r k i n g brakes.
(5) Shift t h e transmission m o m e n t a r i l y i n t o a l l
gear ranges. Then shift t h e transmission back t o
N e u t r a l .
(6) Clean the top o f the filler tube and dipstick t o
keep d i r t f r o m e n t e r i n g the tube.
(7) Check the f l u i d level. Correct level is as follows:
(a) I f fluid is a t n o r m a l operating temperature,
t h e correct level is between the " M a x i m u m Level
H o t " and " A d d " m a r k s (crosshatched area) on the
dipstick.
(b) I f the fluid is only w a r m (85 to 125°F), t h e
correct level is between the two dimples on the dip-
stick.
(8) I f the fluid level is low, add only enough fluid t o
correct the level.
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