AUTOMATIC TRANSMISSION ± Troubleshooting <A/T>
23-29
REFERENCE FOR FAIL-SAFE/BACKUP FUNCTIONS
When malfunctions of the main sensors or actuators are detected by the diagnosis system, the vehicle
is controlled by means of the pre-set control logic to maintain safe conditions for driving.
Malfunctioning item Control contents during malfunction
Output shaft speed
sensor
If there is an open circuit in the output shaft speed sensor, upshifting to 4th gear and lockup
control is stopped.
Inhibitor switch If there is an open circuit in the N, 2 or L signal line, driving is possible in the case of 2 and L
(same as D range) so that control can be performed as if the range is D range, and driving is
not possible in N range. If more than one of the N, 2 or L signals are input, the order of priority
for control is L→2→N.
Accelerator pedal
position sensor
If the output is 0.335 V or less or 4.8 V or more during idling condition, gear shifting control when
throttle is fully closed is carried out.
Solenoid valve No. 3 If a problem is detected, lockup is stopped over the whole range and the solenoid is turned off
to prevent the engine from stalling during idling.
Solenoid valve No. 1,
No. 2
If a problem is detected, each solenoid stops operating and is turned off. The gear shifting logic
when a problem is detected is given in the table below
Selector le-
ver
position
Normal When the solenoid
valve No. 1 has broken
When the solenoid
valve No. 2 has broken
When the solenoid
valves No. 1 and No. 2
have broken
Gear S1 S2 Gear S1 S2 Gear S1 S2 Gear S1 S2
D
1 f
×
3 ×→f 1 f O/D
2 f f 3 f O/D f →× O/D
3
×
f 3 f O/D × O/D
O/D × × O/D × O/D × O/D
2
1 f
×
3 ×→f 1 f 3
2 f f 3 f 3 f →× 3
3
×
f 3 f 3 × 3
L
1 f
×
1 × 1 f 1
2 f f 2 f 1 f 1
f : Energized (ON)
× : Not energized (OFF)
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