Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Fail-safe Chart

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Drivetrain / U881f (automatic Transmission / Transaxle) / Automatic Transaxle System / Fail-safe Chart

FAIL-SAFE CHART

Description

The fail-safe function minimizes the loss of operation when a malfunction occurs in a sensor or solenoid.

Fail-safe

(a) Fail-safe control list:

Malfunctioning Part	Function
Transmission Revolution Sensor (NT)	Shifting to 2nd and 8th gear is prohibited. Lock up clutch control is prohibited. AI-SHIFT* control is prohibited. High response gear shifts are prohibited.
Transmission Revolution Sensor (NC3)	Lock up clutch control is prohibited. AI-SHIFT* control is prohibited. High response gear shifts are prohibited.
Transmission Revolution Sensor (NC)	Shifting to 2nd and 8th gear is prohibited. Lock up clutch control is prohibited. AI-SHIFT* control is prohibited. High response gear shifts are prohibited.
Shift solenoid valve SL1, SL2, SL3, SL4, SL5 and S1	If the ECM detects a solenoid valve malfunction, it performs fail-safe control.
ATF temperature sensor	Shifting to 2nd, 6th, 7th and 8th gear is prohibited. Lock up clutch control is prohibited. High response gear shifts are prohibited.
ECM power supply (voltage is low)	When driving in 1st to 7th gear when a malfunction is detected, the transaxle will be fixed in 7th gear. When driving in 8th gear when a malfunction is detected, the transaxle will be fixed in 8th gear.
Knock sensor	When driving in 1st to 5th gear when a malfunction is detected, up-shift to 6th or higher will be prohibited. When driving in 6th gear or higher when a malfunction is detected, up-shift to a higher gear will be prohibited. Lock up clutch control is prohibited. High response gear shifts are prohibited.
CAN communication	Shifting to only 1st or 3rd gear is allowed. Lock up clutch control is prohibited. High response gear shifts are prohibited.
Shift solenoid valve SLU	Lock up clutch control is prohibited.
Shift solenoid valve SLT	Engine output is limited. High response gear shifts are prohibited.

HINT:

*: In addition to the switching of the shift pattern through the pattern select switch, Artificial Intelligence Shift (AI-SHIFT) control enables the ECM to estimate the road conditions and driver intention in order to automatically select the optimal shift pattern.

(b) Shift Solenoid Valve Normal Operation Chart:

Gear	1st	2nd	3rd	4th	5th	6th	7th	8th
Shift Solenoid Valve SL1	ON	ON	ON	ON	ON	OFF	OFF	OFF
Shift Solenoid Valve SL2	OFF	OFF	OFF	OFF	ON	ON	ON	ON
Shift Solenoid Valve SL3	OFF	OFF	ON	OFF	OFF	OFF	ON	OFF
Shift Solenoid Valve SL4	OFF	OFF	OFF	ON	OFF	ON	OFF	OFF
Shift Solenoid Valve SL5	OFF	ON	OFF	OFF	OFF	OFF	OFF	ON

HINT:

*1: Operation of fail-safe is canceled the first time the vehicle is stopped.
*2: Operation of fail-safe is not canceled for subsequent times the vehicle is stopped.
*3: Operation of fail-safe is canceled at the start of the next trip.
*4: Operation of fail-safe is not canceled, as the vehicle was stopped on the previous trip.
*5: For a shift solenoid valve SL1 OFF malfunction, the 3rd trip is started with the fail-safe ON.
Fail-safe operation is performed when the ECM detects a malfunction.

Fail-safe Control Chart (Shift Solenoid Valve SL1)

Gear Under Normal Conditions	1st	2nd	3rd	4th	5th	6th	7th	8th
ON malfunction (without fail-safe control)	1st	2nd	3rd	4th	5th	5th	5th	5th
Fail-safe control during ON malfunction	1st	2nd	3rd	4th	5th	5th	5th	5th
OFF malfunction (without fail-safe control)	N	N	N	N	N	6th	7th	8th
Fail-safe control during OFF malfunction	6th	6th	6th	6th	6th	6th	7th	8th
Fail-safe control during OFF malfunction	If vehicle is stopped once, fixed in 3rd

Fail-safe Control Chart (Shift Solenoid Valve SL2)

Gear Under Normal Conditions	1st	2nd	3rd	4th	5th	6th	7th	8th
ON malfunction (without fail-safe control)	5th	5th	5th	5th	5th	6th	7th	8th
Fail-safe control during ON malfunction	5th	5th	5th	5th	5th	6th	7th	8th
OFF malfunction (without fail-safe control)	1st	2nd	3rd	4th	1st	N	N	N
Fail-safe control during OFF malfunction (when electrical malfunction detected in any gear between 5th and 8th)	Fixed in 7th
Fail-safe control during OFF malfunction (until vehicle is stopped)	1st	2nd	3rd	4th	4th	4th	4th	4th
Fail-safe control during OFF malfunction (when electrical malfunction detected in any gear between 1st and 4th or malfunction detected in any gear between 1st and 8th)	1st	2nd	3rd	4th	4th	4th	4th	4th

Fail-safe Control Chart (Shift Solenoid Valve SL3)

Gear Under Normal Conditions	1st	2nd	3rd	4th	5th	6th	7th	8th
ON malfunction (without fail-safe control)	3rd	3rd	3rd	3rd	7th	7th	7th	7th
Fail-safe control during ON malfunction (when malfunction detected in any gear between 1st and 3rd)	Fixed in 3rd
Fail-safe control during ON malfunction (when malfunction detected in any gear between 4th and 8th)	Fixed in 7th (If vehicle stops once, fixed in 3rd)
OFF malfunction (without fail-safe control)	1st	2nd	1st	4th	5th	6th	N	8th
Fail-safe control during OFF malfunction	1st	2nd	4th	4th	5th	6th	6th	6th

Fail-safe Control Chart (Shift Solenoid Valve SL4)

Gear Under Normal Conditions	1st	2nd	3rd	4th	5th	6th	7th	8th
ON malfunction (without fail-safe control)	4th	4th	3rd	4th	4th	6th	6th	6th
Fail-safe control during ON malfunction (when malfunction detected in any gear between 1st and 4th)	Fixed in 4th
Fail-safe control during ON malfunction (when malfunction detected in any gear between 5th and 8th)	Fixed in 6th (If vehicle stops once, fixed in 4th)
OFF malfunction (without fail-safe control)	1st	2nd	3rd	1st	5th	N	7th	8th
Fail-safe control during OFF malfunction	1st	2nd	3rd	5th	5th	5th	5th	5th

Fail-safe Control Chart (Shift Solenoid Valve SL5)

Gear Under Normal Conditions	1st	2nd	3rd	4th	5th	6th	7th	8th
ON malfunction (without fail-safe control)	2nd	2nd	3rd	4th	5th	6th	7th	8th
Fail-safe control during ON malfunction (when malfunction detected in 1st or 2nd)	Fixed in 2nd
Fail-safe control during ON malfunction (when malfunction detected in any gear between 3rd and 8th)	Fixed in 8th (If vehicle stops once, gear changes are performed with a shift map specific to 2nd through 8th gear)
OFF malfunction (without fail-safe control)	1st	1st	3rd	4th	5th	6th	7th	N
Fail-safe control during OFF malfunction	1st	3rd	3rd	4th	5th	6th	7th	7th

Fail-safe Control Chart (Shift Solenoid Valve S1)

Gear Under Normal Conditions	1st	2nd	3rd	4th	5th	6th	7th	8th
ON malfunction (without fail-safe control)	1st	2nd	1st	4th	5th	6th	N	8th
Fail-safe control during ON malfunction	1st	2nd	4th	4th	5th	6th	6th	6th
OFF malfunction (without fail-safe control)	1st (3rd)*	2nd	3rd	4th	5th	6th	7th	8th
Fail-safe control during OFF malfunction	Fixed in 4th

Fail-safe Control Chart (Shift Solenoid Valve SLT)

Gear Under Normal Conditions	1st	2nd	3rd	4th	5th	6th	7th	8th
ON malfunction (without fail-safe control) (clutch slipping in any gear due to low line pressure)	1st	2nd	3rd	4th	5th	6th	7th	8th
Fail-safe control during ON malfunction (during engine torque reduction)	1st	2nd	3rd	4th	5th	5th	5th	5th

Gear Under Normal Conditions

1st

2nd

3rd

4th

5th

6th

7th

8th

ON malfunction

(without fail-safe control)

(clutch slipping in any gear due to low line pressure)

1st

2nd

3rd

4th

5th

6th

7th

8th

Fail-safe control during ON malfunction

(during engine torque reduction)

1st

2nd

3rd

4th

5th

HINT:

In the case of an open or short, the ECM stops sending current to the open or shorted solenoid.
*: With S1, D1 or M1 (1st gear) selected

Dtc Check / Clear

DTC CHECK / CLEAR NOTICE: When the diagnosis system is changed from normal mode to check mode or vice versa, all DTCs and freeze frame data recorded in normal mode are cleared. Before changing modes, ...

Data List / Active Test

DATA LIST / ACTIVE TEST DATA LIST NOTICE: In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a pa ...

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Dtc Check / Clear

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