Shift Solenoid A/B Electrical Malfunction (Shift Solenoid Valve No.1/No.2) - Toyota T100 1996 Service Manual

DI−290
DTC P0753, P0758
CIRCUIT DESCRIPTION
Shifting from 1st to O/D is performed in combination with ON and OFF of the shift solenoid valves No.1 and
No.2 controlled by ECM. If an open or short circuit occurs in either of the shift solenoid valves, the ECM con-
trols the remaining normal shift solenoid valve to allow the vehicle to be operated smoothly (Fail safe func-
tion).
Fail safe function:
If either of the shift solenoid valve circuits develops an open or short, the ECM turns the other shift solenoid
ON and OFF to shift to the gear positions shown in the table below. The ECM also turns the shift solenoid
valve SL OFF at the same time. If both solenoids are malfunction, hydraulic control cannot be performed
electronically and must be done manually.
Manual shifting as shown in the following table must be done (In the case of a short circuit, the ECM stops
sending current to the short circuited solenoid).
NORMAL
Position
Solenoid valve
No.1
ON
ON
D
OFF
OFF
ON
2
ON
OFF
ON
L
ON
X: Malfunctions
HINT:
Check the shift solenoid valve No.1 when DTC P0753 is output and check the shift solenoid valve No.2 when
DTC P0758 is output.
DTC No.
ECM checks for open or short circuit in shift solenoid valves
No.1 and No.2 circuit when it changes
ECM records DTC P0753 or P0758 if condition (a) or (b) is
detected once, but it does not light up MIL
After ECM detects condition (a) or (b) continuously 2 times or
more in one−trip, it causes MIL light up until condition (a) or (b)
P0753
disappears
P0758
After that, if ECM detects condition (a) or (b) once, it starts
lighting up MIL again:
(a) Solenoid resistance is 8 Ω or less (short circuit) when sole-
noid is energized
(b) Solenoid resistance is 100 kΩ or more (open circuit) when
solenoid is not energized
1996 TOYOTA T100 (RM449U)
DIAGNOSTICS
SHIFT SOLENOID NO.1
MALFUNCTIONING
Solenoid valve
Gear
No.2 No.1
OFF X
1st
ON
2nd
X
3rd
ON X
OFF O/D
X
OFF 1st X
2nd
ON X
ON 3rd X
OFF X
1st
X
ON 2nd
DTC Detecting Condition
− AUTOMATIC TRANSMISSION
Shift Solenoid A/B Electrical Malfunc-
tion (Shift Solenoid Valve No.1/No.2)
SHIFT SOLENOID NO.2
MALFUNCTIONING
Solenoid valve
Gear
No.2 No.1
ON
ON
3rd
ON
3rd
OFF
3rd
ON OFF
OFF O/D OFF
ON
3rd ON
ON
3rd
OFF
ON OFF
3rd
OFF ON
1st
ON
2nd ON
S Open or short in shift solenoid valve No.1/No.2 circuit
S Shift solenoid valve No.1/No.2
S ECM
BOTH SOLENOIDS
MALFUNCTIONING
Gear when shift selector is
Gear
manually operated
No.2
X
1st
O/D
X
X
O/D
O/D
X
1st
X
3rd
X
X 3rd
X
1st
X
1st
Trouble Area
DI0VP−02
O/D
O/D
O/D
O/D
3rd
3rd
3rd
1st
1st