System Description

WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 2024 Lexus IS 350, 2024 Lexus IS 300, 2023 Lexus IS 350, 2023 Lexus IS 300, and 2022 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.

The ECM uses signals from the transmission revolution sensor (SP2) and transmission revolution sensor (NT) to detect the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear).

The ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, transmission valve body assembly or automatic transmission with transfer assembly (clutch, brake, gear, etc.).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory	Note
P0750-7F	Shift Solenoid "A" Actuator Stuck Off	All of the following conditions are met (2-trip detection logic): Engine coolant temperature is 40°C (104°F) or higher. The vehicle is driven with the shift lever in D. No malfunctions are detected in shift solenoid valve S1, S2, S3, S4, SR, SL1 and SL2, transmission revolution sensors (NT and SP2), engine coolant temperature sensor, knock control sensor, electronic throttle. Either of the following condition is met: Both of the following conditions are met for 0.4 seconds or more1: When the ECM commands the transmission to shift to 1st gear, the actual gear is shifted to 2nd. When the ECM commands the transmission to shift to 5th gear, the actual gear is shifted to 5th. Both of the following conditions are met for 0.4 seconds or more2: When the ECM commands the transmission to shift to 5th gear, the actual gear is shifted to 5th. When the ECM commands the transmission to shift to 6th gear, the engine overruns (clutch slips).	DTC Detection Condition1, 2, 3 and 4 (a): Shift solenoid valve S1 remains open Transmission valve body assembly is blocked Automatic transmission with transfer assembly (clutch, brake, gear, etc.) DTC Detection Condition1, 2, 3 and 4 (b): Shift solenoid valve S1 remains closed Shift solenoid valve SLT remains open or closed Transmission valve body assembly is blocked No. 2 brake malfunction (Driving is difficult.) Automatic transmission with transfer assembly (clutch, brake, gear, etc.)	Comes on	DTC stored	SAE Code: P0751

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

P0750-7F

Shift Solenoid "A" Actuator Stuck Off

All of the following conditions are met (2-trip detection logic):

Engine coolant temperature is 40°C (104°F) or higher.
The vehicle is driven with the shift lever in D.
No malfunctions are detected in shift solenoid valve S1, S2, S3, S4, SR, SL1 and SL2, transmission revolution sensors (NT and SP2), engine coolant temperature sensor, knock control sensor, electronic throttle.
Either of the following condition is met:
1. Both of the following conditions are met for 0.4 seconds or more*1:
  1. When the ECM commands the transmission to shift to 1st gear, the actual gear is shifted to 2nd.
  2. When the ECM commands the transmission to shift to 5th gear, the actual gear is shifted to 5th.
2. Both of the following conditions are met for 0.4 seconds or more*2:
  1. When the ECM commands the transmission to shift to 5th gear, the actual gear is shifted to 5th.
  2. When the ECM commands the transmission to shift to 6th gear, the engine overruns (clutch slips).

DTC Detection Condition1, 2, 3 and 4 (a):

Shift solenoid valve S1 remains open
Transmission valve body assembly is blocked
Automatic transmission with transfer assembly (clutch, brake, gear, etc.)

DTC Detection Condition1, 2, 3 and 4 (b):

Shift solenoid valve S1 remains closed
Shift solenoid valve SLT remains open or closed
Transmission valve body assembly is blocked
No. 2 brake malfunction (Driving is difficult.)
Automatic transmission with transfer assembly (clutch, brake, gear, etc.)

Comes on

DTC stored

SAE Code: P0751

HINT:

Gear positions in the event of a shift solenoid valve mechanical problem:

ECM command gearshift	1st	2nd	3rd	4th	5th	6th
*1: Actual gear position under S1 stuck ON malfunction detected	2nd	2nd	3rd	4th	5th	6th
*2: Actual gear position under S1 stuck OFF malfunction detected	1st	1st	3rd	4th	5th	N*3

*3: Neutral

Gear position during fail-safe operation:

If any malfunction is detected, the ECM changes into the fail-safe mode to shift into the gear positions as shown in the table below.

Gear position under normal conditions	1st	2nd	3rd	4th	5th	6th
*1: Actual gear position under fail-safe mode when S1 stuck ON malfunction	2nd	2nd	3rd	4th	5th	6th
*2: Actual gear position under fail-safe mode when S1 stuck OFF malfunction	1st*3	1st*3	3rd	3rd	3rd	3rd

*3: Under engine braking downshifting to 1st or 2nd gear is prohibited.

DTC DETECTION CONDITION PATTERNS:

		Vehicle Condition
		Pattern 1	Pattern 2
Diagnostic Condition	Engine coolant temperature is 40°C (104°F) or higher.	◦	◦
	The vehicle is driven with the shift lever in D.	◦	◦
	No malfunctions are detected in shift solenoid valve S1, S2, S3, S4, SR, SL1 and SL2, transmission revolution sensors (NT and SP2), engine coolant temperature sensor, knock control sensor, electronic throttle.	◦	◦
Malfunction Condition	When the ECM commands the transmission to shift to 1st gear, the actual gear is shifted to 2nd.	◦	-
	When the ECM commands the transmission to shift to 5th gear, the actual gear is shifted to 5th.	◦	◦
	When the ECM commands the transmission to shift to 6th gear, the engine overruns (clutch slips).	-	◦
Duration		0.4 seconds or more	0.4 seconds or more
Detection Logic		2-trip detection logic	2-trip detection logic

HINT:

This DTC is stored when any of the above detection patterns is met.