AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 LX570)

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Last Modified: 11-27-2007		1.6 C
Service Category: Drivetrain	Section: Automatic Transmission/Transaxle
Model Year: 2008	Model: LX570	Doc ID: RM000000W8003SX
Title: AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 LX570)

DTC

P0756

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

DESCRIPTION

The ECM uses signals from the output shaft speed sensor and input speed sensor 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 with the shift solenoid valves, valve body or automatic transmission (clutch, brake, gear, etc.).

DTC Code

DTC Detection Condition

Trouble Area

P0756

A shift solenoid valve 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 transmission to switch to 5th gear, the actual gear is shifted to 6th.

(b) When the ECM directs the transmission to switch to 6th gear, the actual gear is shifted to 6th.

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

P0756

A shift solenoid valve 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 transmission to switch to 1st gear, the actual gear is shifted to 3rd.

(b) When the ECM directs the transmission to switch to 6th gear, the actual gear is shifted to 5th.

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

HINT:

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

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

MONITOR DESCRIPTION

This DTC indicates a stuck ON malfunction or stuck OFF malfunction of shift solenoid valve S2.

The ECM commands gear shifts by turning the shift solenoid valves ON/OFF. When the gear position commanded by the ECM and the actual gear position are not the same, the ECM illuminates the MIL and stores the DTC.

MONITOR STRATEGY

Related DTCs	P0756: Shift solenoid valve S2/OFF malfunction Shift solenoid valve S2/ON malfunction
Required sensors/Components	Shift solenoid valve S2
Frequency of operation	Continuous
Duration	0.4 sec.
MIL operation	2 driving cycles
Sequence of operation	None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever the following DTCs are not stored	P0115 - P0118: ECT sensor P0125: Insufficient ECT for closed loop P0500: VSS P0748 - P0798: Trans solenoid (range)
Turbine speed sensor circuit	Not circuit malfunction
Output speed sensor circuit	Not circuit malfunction
Shift solenoid valve S1 circuit	Not circuit malfunction
Shift solenoid valve S2 circuit	Not circuit malfunction
Shift solenoid valve S3 circuit	Not circuit malfunction
Shift solenoid valve S4 circuit	Not circuit malfunction
Shift solenoid valve SR circuit	Not circuit malfunction
Shift solenoid valve SL1 circuit	Not circuit malfunction
Shift solenoid valve SL2 circuit	Not circuit malfunction
ECT (Engine Coolant Temperature) sensor circuit	Not circuit malfunction
KCS sensor circuit	Not circuit malfunction
ETCS (Electric Throttle Control System)	Not system down
Transmission position	D
Duration time from shifting N to D	4 sec. or more
ECT	40°C (104°F) or higher
Spark advance from max. retard timing by KCS control	0° crankshaft angle or more
Engine	Starting
Transfer position	HIGH*

HINT:

*: Following conditions met

Vehicle speed sensor circuit	Not circuit malfunction
Output shaft speed sensor circuit	Not circuit malfunction
Transfer output speed	143 rpm or more
Transfer input speed/Transfer output speed (NO/NOtf)	0.9 or more, and less than 1.1

OFF malfunction (A)

ECM selected gear	1st
Vehicle speed	2 km/h (1.3 mph) or more, and less than 40 km/h (24.8 mph)
Engine speed - Turbine speed (NE - NT)	50 rpm or more

OFF malfunction (B)

ECM selected gear

6th

Vehicle speed

2 km/h (1.3 mph) or more

Throttle valve opening angle

9% or more at 2000 rpm

(Conditions vary with engine speed)

ON malfunction (A)

ECM selected gear

5th

Vehicle speed

2 km/h (1.3 mph) or more

Throttle valve opening angle

9% or more at 2000 rpm

(Conditions vary with engine speed)

ON malfunction (B)

ECM selected gear

6th

Vehicle speed

2 km/h (1.3 mph) or more

Throttle valve opening angle

9% or more at 2000 rpm

(Conditions vary with engine speed)

TYPICAL MALFUNCTION THRESHOLDS

[OFF malfunction]

When both conditions below are met: OFF malfunction (A) and (B)

OFF malfunction (A)

Turbine speed/Output speed (NT/NO)

1.24 or more, and 1.49 or less

(This means actual gear is 3rd)

OFF malfunction (B)

Turbine speed/Output speed (NT/NO)

0.66 or more, and 0.80 or less

(This means actual gear is 5th)

[ON malfunction]

When both conditions below are met: ON malfunction (A) and (B)

ON malfunction (A)

Turbine speed/Output speed (NT/NO)

0.51 or more, and 0.65 or less

(This means actual gear is 6th)

ON malfunction (B)

Turbine speed/Output speed (NT/NO)

0.51 or more, and 0.65 or less

(This means actual gear is 6th)

INSPECTION PROCEDURE

1. ACTIVE TEST

HINT:

Using the Techstream to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.

(a) Warm up the engine.

(b) Turn the engine switch off.

(d) Turn the engine switch on (IG).

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / Engine and ECT / Active Test.

(g) According to the display on the Techstream, perform the Active Test.

HINT:

While driving, the shift position can be forcibly changed with the Techstream.

Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem .

Engine and ECT

Tester Display

Test Part

Control Range

Diagnostic Note

Control the Shift Position

Operate shift solenoid valve and set each shift position

Press "→" button: Shift up
Press "←" button: Shift down

It is possible to check the operation of the shift solenoid valves.

[Vehicle Condition]

The vehicle speed is 50 km/h (31 mph) or less.

HINT:

This test can be conducted when the vehicle speed is 50 km/h (31 mph) or less.
The 4th to 5th and 5th to 6th up-shifts must be performed with the accelerator pedal released.
The 6th to 5th and 5th to 4th down-shifts must be performed with the accelerator pedal released.
Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.
The shift position commanded by the ECM is shown in the Data List display on the Techstream.

Shift solenoid valve S2 turns ON/OFF normally when the shift lever is in D.

ECM gear shift command	1st	2nd	3rd	4th	5th	6th
Shift solenoid valve S2	ON	ON	OFF	OFF	OFF	ON

PROCEDURE

1.	CHECK DTC OUTPUT (IN ADDITION TO DTC P0756)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read the DTCs using the Techstream.

Result

Result	Proceed to
Only P0756 is output	A
P0756 and other DTCs are output	B

HINT:

If any other codes besides P0756 are output, perform troubleshooting for those DTCs first.

2.	INSPECT SHIFT SOLENOID VALVE S2

(a) Remove shift solenoid valve S2.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
Shift solenoid valve S2 connector terminal - Shift solenoid valve S2 body	20°C (68°F)	11 to 15 Ω

(c) Apply battery voltage (12 V) to the shift solenoid valve and check that the valve moves and makes an operating noise.

OK:

Measurement Condition	Specified Condition
Battery positive (+) → Shift solenoid valve S2 connector Battery negative (-) → Shift solenoid valve S2 body	Valve moves and makes an operating noise

3.	INSPECT TRANSMISSION VALVE BODY ASSEMBLY

(a) Check the transmission valve body assembly .

OK:

There are no foreign objects on any valve.