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AUTOMATIC TRANSMISSION
Diagnosis System
DESCRIPTION
1. A self–diagnosis function is built into the electrical control
system. Warning is indicated by the overdrive OFF indica–
tor light.
HINT: Warning and diagnostic trouble codes can be
read only when the overdrive switch is ON. If OFF, the
overdrive OFF light is lit continuously and will not blink.
(a) If a malfunction occurs within the vehicle speed sen–
(b) The diagnostic trouble code can be read by the num–
(c) The throttle position sensor or brake signal are not
(d) The signals to each gear can be checked by measur–
2. The diagnostic trouble code is retained in memory by the
ECM and due to back–up voltage, is not canceled out
when the engine is turned off. Consequently, after repair,
it is necessary to turn the ignition switch off and remove
the MFI fuse (15A) or disconnect the EC M connector to
cancel out the diagnostic trouble code. (See page AT–56)
HINT:
CHECK "O/D OFF" INDICATOR LIGHT
1. Turn the ignition switch ON.
2. The "O/D OFF" light will come on when the O/D switch
is placed at OFF.
3. When the O/D switch is set to ON, the–O/D OFF" light
should go out.
If the–O/D OFF" light flashes when the O/D switch is set to
ON, the electronic control system is faulty.
–
Troubleshooting (Diagnosis System)
sors (No. 1 or 2) or solenoids (No. 1 or 2), the over–
drive OFF light will blink to warn the driver.
However, there will be no warning of a malfunction
with lock–up solenoid.
ber of blinks of the overdrive OFF indicator light
when terminals TIE, and E l are connected. (See
page AT–56)
indicated, but inspection can be made by checking
the voltage at terminal TT of the data link connector
1.
ing the voltage at terminal TT of the data link con–
nectar 1 while driving.
Low battery positive voltage will cause faulty opera–
tion of the diagnosis system. Therefore, always check
the battery first.
Use a voltmeter and ohmmeter that have an imped–
ance of at least 10 k
W/
v.
AT–54
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Table of Contents
Troubleshooting
