Last Modified: 7-3-2017 6.8:8.0.40 Doc ID: RM000002SNB008X
Model Year Start: 2007 Model: LX470 Prod Date Range: [08/2006 -           ]
Title: A750F AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: P0746,P0771; Pressure Control Solenoid "A" Performance (Shift Solenoid Valve SL1); 2007 MY LX470 [08/2006 -        ]

DTC

P0746

Pressure Control Solenoid "A" Performance (Shift Solenoid Valve SL1)

DTC

P0771

Shift Solenoid "E" Performance (Shift Solenoid Valve SR)

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 or 5th 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.

DTC Detection Condition

Trouble Area

P0746

The gear required by the ECM does not match the actual gear when driving (2-trip detection logic)
  • Shift solenoid valve SL1 remains closed
  • Shift solenoid valve SR remains open or closed
  • Valve body is blocked
  • Automatic transmission (clutch, brake or gear, etc.)

P0771

The gear required by the ECM does not match the actual gear when driving (2-trip detection logic)
  • Shift solenoid valve SR remains open or closed
  • Shift solenoid valve SL1 remains closed
  • Valve body is blocked
  • Automatic transmission (clutch, brake or gear, etc.)

MONITOR DESCRIPTION

This DTC indicates a stuck ON malfunction or stuck OFF malfunction of the shift solenoid valve SR and SL1.

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

P0746: Shift solenoid valve SL1/OFF malfunction

P0771: Shift solenoid valve SR/ON malfunction

P0771: Shift solenoid valve SR/OFF malfunction

Required sensors/Components (Main)

Shift solenoid valve SL1

Shift solenoid valve SR

Required sensors/Components (Related)

Speed sensor (NT), Speed sensor (NO), Crankshaft position sensor (NE)

Frequency of operation

Continuous

Duration

P0746 and P0771 OFF malfunction (A) and (B): 0.4 sec.

P0746 and P0771 OFF malfunction (C): Immediate

P0771 ON malfunction: 0.15 sec.

MIL operation

2 driving cycles

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever this DTC is not present.

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 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 range

"D"

ECT

40°C (104°F) or more

Spark advance from Max. retard timing by KCS control

0° CA or more

Engine

Starting

P0746 and P0771: OFF malfunction (A)

ECM selected gear

5th

Vehicle speed

2 km/h (1.2 mph) or more

Throttle valve opening angle

7.0% or more at 2,000 rpm (Vary with engine speed)

P0746 and P0771: OFF malfunction (B)

Current ECM selected gear

5th

Last ECM selected gear

4th

Continuous time of ECM selecting 4th gear

2 sec. or more

P0746 and P0771: OFF malfunction (C)

Current ECM selected gear

5th

Last ECM selected gear

4th

P0771: ON malfunction

Current ECM selected gear

2nd

Last ECM selected gear

1st

Throttle valve opening angle

(During transition from 1st to 2nd gear)

6.5% or more at 3,000 rpm (Vary with turbine speed)

TYPICAL MALFUNCTION THRESHOLDS

[P0746 and P0771: OFF malfunction]

  • All of the following conditions are met: OFF malfunction (A), (B) and (C)
  • 2 detections are necessary per driving cycle
  • 1st detection; temporary flag ON
  • 2nd detection; pending fault code ON

OFF malfunction (A)

Turbine speed/Output speed

0.93 to 1.07

OFF malfunction (B)

Turbine speed/Output speed

Not change as follow

0.93 to 1.07

↓

0.65 to 0.79

OFF malfunction (C)

Output record from ECM for 4th → 5th upshifting

Recorded

[P0771: ON malfunction]

  • 2 detections are necessary per driving cycle
  • 1st detection; temporary flag ON
  • 2nd detection; pending fault code ON

ON malfunction

Turbine speed - Output speed x 1st gear ratio (NT - NO x 1st gear ratio)

150 rpm or more

INSPECTION PROCEDURE

1. ACTIVE TEST

HINT:

Performing the intelligent tester's ACTIVE TEST allows relay, VSV, actuator and other items to be operated without removing any parts. Performing the ACTIVE TEST early in troubleshooting is one way to save time.

The DATA LIST can be displayed during the ACTIVE TEST.

(a) Warm up the engine.

(b) Turn the ignition switch OFF.

(c) Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.

(d) Turn the ignition switch ON.

(e) Turn the intelligent tester ON.

(f) Enter the following menus: DIAGNOSIS / OBD/MOBD / ECT / ACTIVE TEST.

(g) Perform the ACTIVE TEST using the intelligent tester.

HINT:

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

Comparing the shift position commanded by the ACTIVE TEST with the actual shift position enables you to confirm the problem 2007 MY LX470 [08/2006 -        ]; A750F AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: FAIL-SAFE CHART .

ECM

Tester Display

Test Part

Control Range

Diagnostic Note

SHIFT

Operate shift solenoid valve and set each shift position by yourself
  • Press "→" button: Shift up
  • Press "←" button: Shift down

Possible to check operation of shift solenoid valves

[Vehicle Condition]

50 km/h (30 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 up-shift must be performed with the accelerator pedal released.
  • The 5th to 4th down-shift 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 (SHIFT) display on the intelligent tester.
  • The shift solenoid valve SR and SL1 turns ON/OFF normally when the shift lever is in the D position:

    ECM gear shift command

    1st

    2nd

    3rd

    4th

    5th

    Shift solenoid valve SL1

    OFF

    OFF

    OFF

    OFF

    ON

    Shift solenoid valve SR

    OFF

    OFF

    OFF

    OFF

    ON

PROCEDURE

1.

CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0746 AND P0771)

(a) Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.

(b) Turn the ignition switch ON and push the intelligent tester main switch ON.

(c) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

(d) Read the DTCs using the intelligent tester.

Display (DTC output)

Proceed to
  • Only P0746 and P0771 are output
  • Only P0771 is output

A

P0746, P0771 and other DTCs are output

B

HINT:

If any other codes besides P0746 and P0771 are output, perform troubleshooting for those DTCs first.

B

GO TO DTC CHART

A

2.

PERFORM ACTIVE TEST USING INTELLIGENT TESTER (SHIFT SOLENOID VALVE SLT)

NOTICE:

  • Perform the test at the normal operating ATF temperature: 50 to 80°C (122 to 176°F).
  • Be careful to prevent SST's hose from interfering with the exhaust pipe.
  • Perform the test with the A/C OFF.

HINT:

Performing the intelligent tester's ACTIVE TEST allows relay, VSV, actuator and other items to be operated without removing any parts. Performing the ACTIVE TEST early in troubleshooting is one way to save time. The DATA LIST can be displayed during the ACTIVE TEST.

(a) Remove the test plug on the transmission case center right side and connect SST.

SST: 09992-00095

09992-00231

09992-00271

(b) Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.

(c) Start the engine and warm it up.

(d) Measure the line pressure with SST.

(e) Turn the intelligent tester ON.

(f) Enter the following menus: DIAGNOSIS / OBD/MOBD / ECT / ACTIVE TEST.

(g) Follow the instructions on the tester and perform the ACTIVE TEST.

(h) Measure the line pressure with SST.

ECM

Tester Display

Test Part

Control Range

Diagnostic Note

LINE PRESS UP*

Operate the shift solenoid SLT and raise line pressure

ON or OFF

HINT:

  • OFF: Line pressure up (when Active Test "LINE PRESS UP" is performed, ECM commands SLT solenoid to turn OFF)
  • ON: No action (normal operation)

[Vehicle Condition]

  • Vehicle stopped
  • Engine: idling

HINT:

*: LINE PRESS UP in the Active Test is performed to check the line pressure changes by connecting SST to the automatic transmission, which is used in the Hydraulic Test 2007 MY LX470 [08/2006 -        ]; A750F AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: HYDRAULIC TEST as well. Please note that the pressure values in the Active Test and Hydraulic Test are different.

Line pressure value

DTC output in previous check

Proceed to

Changed

P0746 and P0771

A

Changed

P0771

B

Not changed

-

C
B

GO TO STEP 4

C

REPLACE SHIFT SOLENOID VALVE SLT

A

3.

INSPECT SHIFT SOLENOID VALVE SL1

(a) Remove the shift solenoid valve SL1.

(b) Measure the resistance of the solenoid value.

Standard resistance:

Tester Connection

Condition

Specified Condition

Terminal 1 of the shift solenoid valve SL1 - terminal 2

20°C (68°F)

5.0 to 5.6 Ω

(c) Connect the battery's positive (+) lead with a 21 W bulb to terminal 2 and the negative (-) lead to terminal 1 of the solenoid valve connector. Then check that the valve moves and makes an operating noise.

(d) Check the operating noise of the solenoid valve.

OK:

Solenoid makes operating noise.

NG

REPLACE SHIFT SOLENOID VALVE SL1

OK

4.

INSPECT SHIFT SOLENOID VALVE SR

(a) Remove the shift solenoid valve SR.

(b) Measure the resistance of the solenoid value.

Standard resistance:

Tester Connection

Condition

Specified Condition

Shift solenoid SR connector - Shift solenoid SR body

20°C (68°F)

11 to 15 Ω

(c) Connect the battery's positive (+) lead to the terminal of the solenoid connector, and the negative (-) lead to the solenoid body.

(d) Check the operating noise of the solenoid valve.

OK:

Solenoid makes operating noise.

NG

REPLACE SHIFT SOLENOID VALVE SR

OK

5.

INSPECT TRANSMISSION VALVE BODY ASSEMBLY

(a) Check the transmission valve body assembly.

OK:

There are no foreign objects on each valve.

NG

REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY

OK

REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY