Automatic Transmission System - Fail-Safe Chart

Lexus IS250 IS220d GSE20 ALE20 - A960E AUTOMATIC TRANSMISSION


AUTOMATIC TRANSMISSION SYSTEM - FAIL-SAFE CHART

FAIL-SAFE CHART

This function minimizes the loss of the ECT functions when any malfunction occurs in each sensor or solenoid.
*1: AI (Artificial Intelligence) -SHIFT control
In addition to the switching of the shift pattern through the pattern select switch, the AI-SHIFT control enables the ECM to estimate the road conditions and the driver's intention in order to automatically select the optimal shift pattern. As a result, a comfortable ride has been realized.

Malfunction PartFunction
DTC P0717:
Input Speed Sensor (NT)		During an input speed sensor malfunction, shift control is effected through the output speed sensor signal (SP2).
During an input speed sensor malfunction, up-shift to the 5th and 6th, AI-SHIFT*1 and flex lock-up clutch control are prohibited.
DTC P0500:
Output Speed Sensor (SP2)		During an output speed sensor malfunction, shift control is effected through the input speed sensor signal (NT).
During an output speed sensor malfunction, up-shift to the 5th and 6th, AI-SHIFT*1 and flex lock-up clutch control are prohibited.
DTC P0710, P0712, P0713:
ATF Temperature Sensor		During an ATF temperature sensor malfunction, up-shift to the 5th and 6th and flex lock-up clutch control are prohibited.
Shift Solenoid Valve S1, S2, S3, S4 and SRThe current to the failed solenoid valve is cut off and control is effected by operating the other solenoid valves.
Shift control is effected depending on the failed solenoid as described in the table on the next page.
DTC P0748, P0778:
Shift Solenoid Valve SL1 and SL2		During a solenoid valve SL1 or SL2 malfunction, up-shift to the 5th and 6th and flex lock-up clutch control are prohibited.
DTC P2757, P2759:
Shift Solenoid Valve SLU		During a solenoid valve SLU malfunction, the current to the solenoid valve is stopped. This stops lock-up control and flex lock-up control, fuel economy decreases.
DTC P02714, P2716:
Shift Solenoid Valve SLT		During a solenoid valve SLT malfunction, the current to the solenoid valve is stopped. This stops line pressure optimal control, the shift shock increases. However, shifting is effected through normal clutch pressure control.

Fail-safe operation for electronically malfunctioning shift solenoid valve (S1, S2, S3, S4 and SR):

  • HINT:
  • Fail-safe operation in the event of an electric system malfunction.
  • Fail safe function:
  • If either of the shift solenoid valve circuits has an open or short failure, the ECM turns the other shift solenoid "ON" and "OFF" in order to shift into the gear positions shown in the table below.
  • In case of a short circuit, the ECM stops sending current to the short circuited solenoid.
  • Even if staring the engine again in the fail-safe mode, the gear position remains in the same position.
Fail-safe chart for electrical malfunction:
Shift Lever PositionNormal
GearShift solenoid (ECM output)
S1S2S3S4SRSL1SL2
D, S61stOFFONONOFFONOFFON
2ndONONONOFFONOFFON
3rdONOFFONOFFONOFFON
4thONOFFOFFOFFONOFFON
5thONOFFOFFONOFFONOFF
6thONONOFFONOFFONOFF
S51stOFFONONOFFONOFFON
2ndONONONOFFONOFFON
3rdONOFFONOFFONOFFON
4thONOFFOFFOFFONOFFON
5thONOFFOFFONOFFONOFF
S41stOFFONONOFFONOFFON
2ndONONONOFFONOFFON
3rdONOFFONOFFONOFFON
4thONOFFOFFOFFONOFFON
S31stOFFONONOFFONOFFON
2ndONONONOFFONOFFON
3rd (E/B)ONOFFONOFFONOFFOFF
S21stOFFONONOFFONOFFON
2nd (E/B)ONONONONONOFFOFF
S11st (E/B)OFFONONOFFONOFFOFF
Shift Lever PositionShift Solenoid Valve S1 Electrical Malfunction (P0973, P0974)
Gear*2 Shift solenoid (ECM output)
S1S2S3S4SRSL1SL2
D,S61stXONONOFFONOFFON
1st→4thXON→OFFON→OFFOFFONOFFON
3rd→4thXOFFON→OFFOFFONOFFON
4thXOFFOFFOFFONOFFON
5thXOFFOFFONOFFONOFF
N→5thXON→OFFOFFONOFFONOFF
S51stXONONOFFONOFFON
1st→4thXON→OFFON→OFFOFFONOFFON
3rd→4thXOFFON→OFFOFFONOFFON
4thXOFFOFFOFFONOFFON
5thXOFFOFFONOFFONOFF
S41stXONONOFFONOFFON
1st→4thXON→OFFON→OFFOFFONOFFON
3rd→4thXOFFON→OFFOFFONOFFON
4thXOFFOFFOFFONOFFON
S31stXONONOFFONOFFON
1st→4thXON→OFFON→OFFOFFONOFFON
3rd (E/B)→4thXOFFON→OFFOFFONOFFOFF→ON
S21stXONONOFFONOFFON
1st (E/B)→4thXON→OFFON→OFFOFFONOFFOFF→ON
S11st (E/B)XONONOFFONOFFOFF
  • HINT:
*2: Actual gear shift (gear position) under fail-safe operation.
X: OFF (the ECM stops sending current to a malfunctioning solenoid valve)
→: Condition in the electrical malfunction is shown on the left of "→".
Condition in the fail-safe mode is shown on the right of "→".
(E/B): Engine brake
Shift Lever PositionShift solenoid Valve S2 Electrical Malfunction (P0976, P0977)
Gear*2 Shift solenoid (ECM output)
S1S2S3S4SRSL1SL2
D,S63rdOFF→ONXONOFFONOFFON
3rdONXONOFFONOFFON
3rdONXONOFFONOFFON
4thONXOFFOFFONOFFON
5thONXOFFONOFFONOFF
5thONXOFFONOFFONOFF
S53rdOFF→ONXONOFFONOFFON
3rdONXONOFFONOFFON
3rdONXONOFFONOFFON
4thONXOFFOFFONOFFON
5thONXOFFONOFFONOFF
S43rdOFF→ONXONOFFONOFFON
3rdONXONOFFONOFFON
3rdONXONOFFONOFFON
4thONXOFFOFFONOFFON
S33rd→3rd (E/B)OFF→ONXONOFFONON→OFFOFF
3rd→3rd (E/B)ONXONOFFONON→OFFOFF
3rd (E/B)ONXONOFFONOFFOFF
S23rd→3rd (E/B)OFF→ONXONOFFONON→OFFOFF
3rd (E/B)ONXONOFFONOFFOFF
S13rd (E/B)OFF→ONXONOFFONOFFOFF
  • HINT:
*2: Actual gear shift (gear position) under fail-safe operation.
X: OFF (the ECM stops sending current to a malfunctioning solenoid valve)
→: Condition in the electrical malfunction is shown on the left of "→".
Condition in the fail-safe mode is shown on the right of "→".
(E/B): Engine brake
Shift Lever PositionShift solenoid Valve S3 Electrical Malfunction (P0979, P0980)
Gear*2 Shift solenoid (ECM output)
S1S2S3S4SRSL1SL2
D,S63rd→4thOFF→ONON→OFFXOFFONOFFON
4thONON→OFFXOFFONOFFON
4thONOFFXOFFONOFFON
4thONOFFXOFFONOFFON
5thONOFFXONOFFONOFF
6thONONXONOFFONOFF
S53rd→4thOFF→ONON→OFFXOFFONOFFON
4thONON→OFFXOFFONOFFON
4thONOFFXOFFONOFFON
4thONOFFXOFFONOFFON
5thONOFFXONOFFONOFF
S43rd→4thOFF→ONON→OFFXOFFONOFFON
4thONON→OFFXOFFONOFFON
4thONOFFXOFFONOFFON
4thONOFFXOFFONOFFON
S33rd→4thOFF→ONON→OFFXOFFONOFFON
4thONON→OFFXOFFONOFFON
4thONOFFXOFFONOFFOFF→ON
S23rd→4thOFF→ONON→OFFXOFFONOFFON
6th→4thONON→OFFXOFFONOFFOFF→ON
S11st (E/B)→4thOFF→ONON→OFFXOFFONOFFOFF→ON
  • HINT:
*2: Actual gear shift (gear position) under fail-safe operation.
X: OFF (the ECM stops sending current to a malfunctioning solenoid valve)
→: Condition in the electrical malfunction is shown on the left of "→".
Condition in the fail-safe mode is shown on the right of "→".
(E/B): Engine brake
Shift Lever PositionShift Solenoid Valve S4 Electrical Malfunction (P0982, P0983)
Gear*2 Shift solenoid (ECM output)
S1S2S3S4SRSL1SL2
D,S61stOFFONONXONOFFON
2ndONONONXONOFFON
3rdONOFFONXONOFFON
4thONOFFOFFXONOFFON
4thONOFFOFFXOFF→ONON→OFFOFF→ON
4thONON→OFFOFFXOFF→ONON→OFFOFF→ON
S51stOFFONONXONOFFON
2ndONONONXONOFFON
3rdONOFFONXONOFFON
4thONOFFOFFXONOFFON
4thONOFFOFFXOFF→ONON→OFFOFF→ON
S41stOFFONONXONOFFON
2ndONONONXONOFFON
3rdONOFFONXONOFFON
4thONOFFOFFXONOFFON
S31stOFFONONXONOFFON
2ndONONONXONOFFON
3rd (E/B)ONOFFONXONOFFOFF
S21stOFFONONXONOFFON
2nd (E/B)ONONONXONOFFOFF
S11st (E/B)OFFONONXONOFFOFF
  • HINT:
*2: Actual gear shift (gear position) under fail-safe operation.
X: OFF (the ECM stops sending current to a malfunctioning solenoid valve)
→: Condition in the electrical malfunction is shown on the left of "→".
Condition in the fail-safe mode is shown on the right of "→".
(E/B): Engine brake
Shift Lever PositionShift Solenoid Valve SR Electrical Malfunction (P0985, P0986)
Gear*2 Shift solenoid (ECM output)
S1S2S3S4SRSL1SL2
D,S61stOFFONONOFFXOFFON
2ndONONONOFFXOFFON
3rdONOFFONOFFXOFFON
4thONOFFOFFOFFXOFFON
5thONOFFOFFONXONOFF
6thONONOFFONXONOFF
S51stOFFONONOFFXOFFON
2ndONONONOFFXOFFON
3rdONOFFONOFFXOFFON
4thONOFFOFFOFFXOFFON
5thONOFFOFFONXONOFF
S41stOFFONONOFFXOFFON
2ndONONONOFFXOFFON
3rdONOFFONOFFXOFFON
4thONOFFOFFOFFXOFFON
S31stOFFONONOFFXOFFON
2ndONONONOFFXOFFON
3rdONOFFONOFFXOFFOFF
S21stOFFONONOFFXOFFON
2ndONONONOFFXOFFOFF
S11stOFFONONOFFXOFFOFF
  • HINT:
*2: Actual gear shift (gear position) under fail-safe operation.
X: OFF (the ECM stops sending current to a malfunctioning solenoid valve)
→: Condition in the electrical malfunction is shown on the left of "→".
Condition in the fail-safe mode is shown on the right of "→".
(E/B): Engine brake

Fail-safe operation for mechanically malfunction:

  • HINT:
  • Fail-safe operation in the event of a mechanical system malfunction.
  • Fail safe function:
  • The ECM controls the gear position as shown in the table below when malfunctions occur.
Fail-safe chart for mechanical malfunction:
DTCConditionGear*2
-Normal1st2nd3rd4th5th6th
P0751Shift solenoid valve S1:
Stuck OFF malfunction		1st*3 1st*3 ↑3rd3rd3rd
P0761Shift solenoid S3:
Stuck ON malfunction		1st2nd↑3rd3rd3rd
P0766Shift solenoid valve S4, Shift solenoid valve SL2 or Valve body (Brake control valve):
Malfunction		1st2nd↑3rd3rd3rd
P0781Valve body (1-2 shift valve):
Malfunction		1st*3 1st*3 ↑3rd3rd3rd
P0729Valve body (Reverse sequence valve):
Malfunction		1st2nd↑3rd3rd3rd
  • HINT:
*2: Actual gear shift (gear position) under fail-safe operation
*3: Under engine braking, downshifting to 1st or 2nd gear is prohibited.