System Description

WARNING: This page is about a different car, the 2015 Lexus IS 250 and 2014 Lexus IS 250. 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).

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

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P0756	Shift Solenoid "B" Performance (Shift Solenoid Valve S2)	[S2 stuck ON malfunction1:] Shifting to 3rd and 5th gears is impossible. The ECM determines there is a malfunction when the following conditions are both met. (2-trip detection logic) (a) When the ECM directs the gearshift to change to 5th gear, the actual gear is shifted to 6th. (b) When the ECM directs the gearshift to change to 6th gear, the actual gear is shifted to 6th. [S2 stuck OFF malfunction2:] The vehicle starts in 3rd gear and shifting to 6th gear is impossible. The ECM determines there is a malfunction when the following conditions are both met. (2-trip detection logic) (a) When the ECM directs the gearshift to change to 1st gear, the actual gear is shifted to 3rd. (b) When the ECM directs the gearshift to change to 6th gear, the actual gear is shifted to 5th.	[S2 stuck ON malfunction1:] Shift solenoid valve S2 remains open Valve body is blocked Automatic transmission (clutch, brake or gear, etc.) [S2 stuck OFF malfunction2:] Shift solenoid valve S2 remains closed Valve body is blocked Automatic transmission (clutch, brake or gear, etc.)	Comes on	DTC stored

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P0756

Shift Solenoid "B" Performance (Shift Solenoid Valve S2)

[S2 stuck ON malfunction*1:]
Shifting to 3rd and 5th gears is impossible.
The ECM determines there is a malfunction when the following conditions are both met. (2-trip detection logic)

(a) When the ECM directs the gearshift to change to 5th gear, the actual gear is shifted to 6th.
(b) When the ECM directs the gearshift to change to 6th gear, the actual gear is shifted to 6th.

[S2 stuck OFF malfunction*2:]
The vehicle starts in 3rd gear and shifting to 6th gear is impossible.
The ECM determines there is a malfunction when the following conditions are both met. (2-trip detection logic)

(a) When the ECM directs the gearshift to change to 1st gear, the actual gear is shifted to 3rd.
(b) When the ECM directs the gearshift to change to 6th gear, the actual gear is shifted to 5th.

[S2 stuck ON malfunction*1:]

Shift solenoid valve S2 remains open
Valve body is blocked
Automatic transmission (clutch, brake or gear, etc.)

[S2 stuck OFF malfunction*2:]

Shift solenoid valve S2 remains closed
Valve body is blocked
Automatic transmission (clutch, brake or gear, etc.)

Comes on

DTC stored

HINT:

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

ECM commanded gear	1st	2nd	3rd	4th	5th	6th
*1: Actual gear position under S2 stuck ON malfunction	1st	2nd	2nd	4th	6th	6th
*2: Actual gear position under S2 stuck OFF malfunction	3rd	3rd	3rd	4th	5th	5th