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Automatic Transmission
Symptom Troubleshooting Index (cont'd)
Symptom
Probable cause(s)
Notes
No shift
Modulator valve defective
Measure line pressure.
Erratic shifting
gears:
Fails to shift in H
position; does not
upshift to 4th
1.
Shift solenoid valve A
defective
2.
Mainshaft speed sensor
defective
3.
Countershaft speed sensor
defective
4.
Shift valve A defective
5.
Shift valve D defective
• Inspect the O-ring, and check the shift solenoid valve
for seizure.
• Check the H indicator indication, and check for
loose connectors. Inspect the transmission range
switch. If the transmission range switch is faulty,
replace it. If the transmission range switch is out of
adjustment, adjust it and the shift cable.
Erratic shifting
gears:
Fails to shift in E
and H positions;
does not upshift to
3rd and 4th
1.
Shift solenoid valve B
defective
2.
Shift fork shaft stuck
3.
Shift valve B defective
4.
Servo control valve
defective
• Check the B indicator indication, and check for
loose connectors. Inspect the O-ring, and check the
shift solenoid valve for seizure.
• Check for a missing shift fork bolt on the shift fork
shaft.
Erratic shifting
gears:
Fails to shift in B ,
El
and
C D
positions; starts off
in 3rd
1.
Shift solenoid valve B
defective
2.
Shift valve B defective
3.
Shift valve E defective
Check the E indicator indication, and check for
loose connectors. Inspect the O-ring, and check the shift
solenoid valve for seizure.
Excessive shock,
or flares on all
upshifts and
downshifts
1.
A/T clutch pressure control
solenoid valves A and B
defective
2.
C P C valve A defective
3.
C P C valve B defective
4.
Foreign material in
separator plate orifice
• Check the B indicator indication, and check for
loose connectors. Inspect the A/T clutch pressure
control solenoid valve body gasket and ATF feed
pipes for wear and damage. If the A/T clutch pressure
control solenoid valve is stuck, inspect the CPC valves.
• If the ATF strainer is clogged with particles of steel or
aluminum, inspect the ATF pump. If the ATF pump is
OK, and no cause for the contamination is found,
replace the torque converter.
Excessive shock or
flares on 1-2
upshift or 2-1
downshift
1.
Shift solenoid valve C
defective
2.
2nd clutch pressure switch
defective
3.
Foreign material in
separator plate orifice
4.
Shift valve C defective
5.
1st accumulator defective
6.
2nd accumulator defective
7.
1st check ball stuck
8.
2nd check ball stuck
9.
1st clutch defective
10.
2nd clutch defective
• Check the B indicator indication, and check for
loose connectors. Inspect the O-rings, and check the
shift solenoid valve for seizure. Check that the outlet
is not clogged inside of the 2nd clutch pressure
switch connector.
• Check 1st and 2nd clutch pressures.
• Inspect the clutch piston and O-rings. Check the
spring retainer for wear and damage. Inspect the
clutch end plate-to-top disc clearance. If the clearance
is out of tolerance, inspect the clutch discs and plates
for wear and damage. If the discs and plates are worn
or damaged, replace them as a set. If they are OK,
adjust the clutch end plate clearance.
14-14
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Table of Contents
Troubleshooting
