7B-8 AUTOMATIC TRANSMISSION (4 A/T)
Fail safe function
This function is provided by the safe mechanism that assures safe driveability even when the solenoid valve,
sensor or its circuit fails.
The table below shows the fail safe function for each fail condition of sensor, solenoid or its circuit.
Area Detecting condition Fail safe function
Input/Turbine
speed sensor cir-
cuit
(DTC P0715)
Input shaft speed
sensor signal voltage
is too high or too low.
• When vehicle running and in shift change by automatic elec-
tronic control, gear is fixed to gear which is going to be
selected and lock-up function is turned OFF.
• When vehicle running and in no shift change, gear is fixed to
gear right before the trouble occurred and lock-up function is
turned OFF.
• When vehicle is at stop after or during detecting trouble, or in
shift change by manual operation while running, gear is fixed
as the followings and lock-up function is turned OFF.
“P” range → P, “R” range → R, “N” range → N,
“D” range → 3rd, “2” range → 2nd, “L” range → 1st
Output shaft speed
sensor circuit
(DTC P0720)
Output shaft speed
sensor signal voltage
is too high or too low.
Shift solenoid
(DTC P0753)
(DTC P0758)
(DTC P0763)
(DTC P0768)
(DTC P0773)
• Solenoid output
voltage is too high
although TCM
orders solenoid to
turn off.
• Solenoid output
voltage is too low
although TCM
orders solenoid to
turn on.
• When select lever is “P”, “R”, “N”, “D” or “2” range, A/T sole-
noid power relay is turned OFF and gear is fixed as follows :
“P” range → P, “R” range → R, “N” range → N,
“D” range → 3rd
• When select lever is “2” range, gear is fixed to pre pro-
grammed gear position of several patterns as follows :
– Malfunction of No.1 solenoid → 3rd
– Malfunction of No.2 solenoid → 3rd
– Malfunction of No.3 solenoid → 2nd
– Malfunction of No.4 solenoid → 1st or 2nd
– Malfunction of No.5 solenoid → 2nd or 3rd
– Malfunction of 2 or more solenoids → 3rd
• When select lever is “L” range, gear is fixed to pre pro-
grammed gear position of several patterns as follows :
– Malfunction of No.1 solenoid → 3rd
– Malfunction of No.2 solenoid → 1st
– Malfunction of No.3 solenoid → 2nd
– Malfunction of No.4 solenoid → 1st or 2nd
– Malfunction of No.5 solenoid →1st
– Malfunction of 2 or more solenoids → 3rd
TCC circuit
(DTC P0743)
Lock-up function is turned OFF.
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