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TURBO HYDRA-MATIC 4 0 0 AUTOMATIC TRANSMISSION
II. SPECIFIC TRANSMISSION
MALFUNCTIONS
See Charts A through F.
Ill. CAUSES OF TRANSMISSION
MALFUNCTIONS
IMPROPER VACUUM AT MODULATOR
1.
ENGINE
A. TUNE UP.
B. LOOSE FITTING.
C. VACUUM OPERATED ACCESSORY LEAK
(HOSES, VACUUM ADVANCE, ETC).
D. ENGINE EXHAUST SYSTEM RESTRICTED.
E. EXHAUST GAS RECIRCULATION (EGR)
VALVE.
2. VACUUM LINE TO MODULATOR
A. LEAK.
B. LOOSE FITTING.
C. RESTRICTED ORIFICE OR INCORRECT
ORIFICE SIZE.
D. CARBON BUILD UP AT MOD. VAC. FITTING.
E. PINCHED LINE.
F. GREASE IN PIPE (NO OR DELAYED UPSHIFT-
COLD).
CONTROL VALVE ASSEMBLY
-
GOVERNOR LlNE PRESSURE CHECK
1. INSTALL LINE PRESSURE GAGE.
2. INSTALL TACHOMETER.
3.
DISCONNECT
VACUUM
LINE
TO
MODULATOR.
4.
WITH
VEHICLE ON HOIST (DRIVING
WHEELS OFF GROUND), FOOT OFF BRAKE, IN
DRIVE, CHECK LINE PRESSURE AT 1000 rpm.
5. SLOWLY INCREASE ENGINE rpm TO 3000 rpm
AND DETERMINE I F A LINE PRESSURE DROP
OCCURS (lo PSI OR MORE).
6. I F PRESSURE DROP OF 10 PSI OR MORE
OCCURS, DISASSEMBLE, CLEAN AND INSPECT
CONTROL VALVE ASSEMBLY.
7. IF PRESSURE DROP IS LESS THAN 10 PSI:
A. INSPECT GOVERNOR
1. STUCK VALVE.
2. WEIGHT FREENESS.
3.
RESTRICTED
ORIFICE
IN
GOVERNOR
VALVE.
4. CHECK GOVERNOR VALVE ENTRY AND
EXHAUST (.02OV min.).
B. GOVERNOR FEED SYSTEM
1. CHECK SCREEN IN CONTROL VALVE
ASSEMBLY OR CASE.
2. CHECK FOR RESTRICTIONS IN GOVERNOR
PIPE.
3. CHECK FOR FIT OF GOVERNOR PIPES IN
CASE HOLES.
LOW LlNE PRESSURE
1. LOW TRANSMISSION OIL LEVEL.
2. MODULATOR ASSEMBLY
-
PERFORM A
BELLOWS
COMPARISON
CHECK
(SEE
"INSPECTION OF MODULATOR AND VALVE").
TRANSMISSION MALFUNCTION RELATED TO OIL PRESSURE
I
MALFUNCTION
NO 1-2 UPSHIFT
AND/OR DELAYED
UPSHIFT
SLIPPING-REVERSE
SLIPPING-1ST GEAR
NO DETENT
DOWNSHIFTS
t
'DRIVE RANGE, VACUUM LlNE DISCONNECTED FROM MODULATOR.
3820
NOTE: A DASH
(-)
IN THE ABOVE CHART MEANS THAT THE OIL PRESSURE READING HAS NO MEANING UNDER THE TEST CONDITION.
Fig. 7A4-7 Preliminary Diagnosis Chart
CHART")
PRESSURE
O E $ ~ ~ , " ~ ~ E
OF^^^
WHEELS FREE
TO MOVE*
10 PSI DROP
OR MORE
LESS THAN
10 PSI DROP
DROP
---
DROP
---
NORMAL
NEUTRAL
BRAKES
APPLIED
1000 RPM
OIL
'RESSURE
NORMAL
NORMAL
NORMAL
HIGH
NORMAL
NORMAL
OBTAINED FROM
DRIVE
BRAKES
APPLIED
1000 RPM
OIL
PRESSURE
NORMAL
NORMAL
HIGH
HIGH
NORMAL
LOW TO
NORMAL
NORMAL
(PRESSURES
DRIVE
IDLE
OIL
PRESSURE
NORMAL
NORMAL
HIGH
HIGH
NORMAL
LOW TO
NORMAL
NORMAL
DRIVE
W3FD
THROTTLE
OIL
PRESSURE
---
NORMAL
LOW TO
NORMAL
~
~
~
~
~
~
MALFUNCTION I N
CONTROL VALVE ASSY.
MALFUNCTION IN
GOVERNOROR
GOVERNOR FEED
SYSTEM
MALFUNCTION IN
DETENT SYSTEM
MALFUNCTION IN
MODULATOR OR
VACUUM FEED SYSTEM
TO MODULATOR
OIL LEAK IN FEED
SYSTEM TO THE
DIRECT CLUTCH
OIL LEAK IN FEED
SYSTEM TO THE
FORWARD CLUTCH
MALFUNCTlON
IN
DFTFNT CVSTFM
THE
SUPER OR LO
BRAKES
APPLIED
1000 RPM
OIL
PRESSURE
NORMAL
NORMAL
NORMAL
NORMAL
NORMAL
LOW TO
NORMAL
NORMAL
"PRELIMINARY
REVERSE
BRAKES
APPLIED
1000 RPM
OIL
PRESSURE
NORMAL
NORMAL
NORMAL
HIGH
LOW
NORMAL
CHECKING PROCEDURE
DRIVE-BRAKES
APPLIED 1000 RPM
DOWNSHIFT
SWITCH ACTIVATED
OIL
PRESSURE
NORMAL
NORMAL
NORMAL
-
--
NORMAL
LOW TO
NORMAL
LOW
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