T M 9 - 2 3 2 0 - 2 7 9 - 3 4 - 1
Troubleshooting Malfunctions (Cont)
T a b l e 2 - 3 . T r o u b l e s h o o t i n g ( C o n t )
Malfunction
Test or Inspection
Corrective Action
T R A N S M I S S I O N ( C O N T )
7 . A U T O M A T I C S H I F T S O C C U R A T T O O L O W A S P E E D O R S H I F T S R O U G H.
Step 1. Check for defective modulator valve. Remove modulator valve from transmission
(para 7-21). Apply 70 psi (483 kPa) air pressure at modulator valve hose fitting. Check that
modulator valve plunger moves as air is applied. Modulator valve must not leak air when
operated.
If modulator valve does not operate properly, or is damaged, replace modulator
valve (para 7-21).
Step 2. Check for defective control valve. Remove modulator valve (para 7-21). Check valve stop in
transmission for free movement in. Check that spring pushes valve stop out when released
and is not damaged.
If valve stop does not move freely or spring is damaged or does not push valve stop
out, repair control valve (para 7-20).
Step 3. Check for high rear governor pressure. Remove plug from rear governor test port. Install a
0 to 200 psi (0 to 1380 kPa) gage at rear governor test port. Start engine and shift
transmission into DRIVE. Release parking brake and drive vehicle until engine tachometer
reads approximately 1650 rpm. Check for 83 to 91 psi (573 to 628 kPa) rear governor
pressure.
If pressure is over 91 psi (628 kPa) replace governor valve (para 7-23).
If pressure is 83 to 91 psi (573 to 628 kPa) repair control valve body (para 7-20).
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