Dtc P0766 Shift Solenoid D Performance (Shift Solenoid Valve S4)

Transmission. Lexus Gs430, Gs300. Uzs190 Grs190
A761E Automatic Transmission. Lexus Gs430, Gs300. Uzs190 Grs190

SYSTEM DESCRIPTION

MONITOR DESCRIPTION

INSPECTION PROCEDURE

CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0766)

INSPECT SHIFT SOLENOID VALVE S4

INSPECT SHIFT SOLENOID VALVE SL2

INSPECT SHIFT SOLENOID VALVE SLT

INSPECT TRANSMISSION VALVE BODY ASSEMBLY

DTC P0766 Shift Solenoid "D" Performance (Shift Solenoid Valve S4)


SYSTEM 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 of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear, etc.).

DTC No.
DTC Detection Condition
Trouble Area
P0766
  1. "S4 stuck OFF malfunction", "SL2 stuck ON malfunction" or "Brake control valve malfunction"*1:
    Shifting to 5th and 6th gears is impossible.
    The ECM determines there is a malfunction when the following conditions are both met.(2-trip detection logic)
    1. When the ECM directs the gearshift to switch to 5th gear, the actual gear is shifted to 4th.
    2. When the ECM directs the gearshift to switch to 6th gear, the actual gear is shifted to 4th.
  1. Shift solenoid valve S4 remains closed
  2. Shift solenoid valve SL2 remains open
  3. Shift solenoid valve SLT remains open or closed
  4. Valve body is blocked (Brake control valve)
  5. Automatic transmission (clutch, brake or gear, etc.)
HINT:
  1. Gear positions in the event of a solenoid valve mechanical problem:

    ECM command gearshift
    		1st
    		2nd
    		3rd
    		4th
    		5th
    		6th
    *1: Actual gear position under malfunction
    		↑
    		↑
    		↑
    		↑
    		4th
    		4th
  2. 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
    		↑
    		↑
    		↑
    		3rd
    		3rd
    		3rd

MONITOR DESCRIPTION

This DTC indicates "stuck OFF malfunction" of the shift solenoid valve S4, "stuck ON malfunction" of the shift solenoid valve SL2, or brake control valve malfunction. 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 same, the ECM illuminates the MIL and stores the DTC.

INSPECTION PROCEDURE


ACTIVE TEST
HINT:
Performing the intelligent tester Active Test allows relay, Vacuum Switching Valve (VSV), actuator and other items to be operated without removing any parts. Performing the Active Test early in troubleshooting is one way to shorten labor time.
The Data List can be displayed during the Active Test.

  1. Warm up the engine.

  2. Turn the engine switch off.

  3. Connect the intelligent tester to the DLC3.

  4. Turn the engine switch on (IG) Position.

  5. Turn on the tester.

  6. Select the item "Enter / Power train / ECT / Active Test".

  7. Follow the instructions on the tester and read the Active Test.

    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 (Click here).

    Item
    		Test Details
    		Diagnostic Note
    Control the Shift Position
    		[Test Details]
    Operate the shift solenoid valve and set the each shift position by yourself.
    [Vehicle Condition]
    1. IDL: ON
    2. Less than 50 km/h (31 mph)
    [Others]
    1. Press "→" button: Shift up
    2. Press "←" button: Shift down
    		Possible to check the operation of the shift solenoid valves.
    HINT:
    1. This test can be conducted when the vehicle speed is 50 km/h (31 mph) or less.
    2. The 4th to 5th and 5th to 6th up-shiftings must be performed with the accelerator pedal released.
    3. The 6th to 5th and 5th to 4th down-shiftings must be performed with the accelerator pedal released.
    4. Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.
    5. The shift position commanded by the ECM is shown in the DATA LIST (Shift Status) display on the intelligent tester.
    6. The shift solenoid valve S4 and SL2 are turned on/off normally when the shift lever is in the D position:

      ECM command gearshift
      		1st
      		2nd
      		3rd
      		4th
      		5th
      		6th
      Shift solenoid valve S4
      		OFF
      		OFF
      		OFF
      		OFF
      		ON
      		ON
      Shift solenoid valve SL2
      		ON
      		ON
      		ON
      		ON
      		OFF
      		OFF
1.CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0766)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG) position.

  1. Turn on the tester.

  1. Select the item "Power train / ECT / DTC / Current or Pending".

  1. Read the DTCs using the intelligent tester.

    Result:

    Display (DTC output)
    		Proceed to
    Only "P0766" is output
    		A
    "P0766" and other DTCs
    		B
    HINT:
    If any other codes besides "P0766" are output, perform troubleshooting for those DTCs first.


B
GO TO DTC CHART
A


2.INSPECT SHIFT SOLENOID VALVE S4


    Lexus Gs430, Gs300. Uzs190 Grs190.A761E Automatic Transmission.Electronic Controlled Automatic Transmission System. Dtc P0766 Shift Solenoid D Performance (Shift Solenoid Valve S4)

  1. Remove the shift solenoid valve S4.

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

    Resistance:
    Tester Connection
    		Specified Condition
    20°C (68°F)
    Solenoid Connector (S4) - Solenoid Body (S4)
    		11 to 15 Ω

  1. Connect the positive (+) lead to the terminal of the solenoid connector, and the negative (-) lead to the solenoid body.

    OK:
    The solenoid makes an operating sound.


NG
REPLACE SHIFT SOLENOID VALVE S4
OK


3.INSPECT SHIFT SOLENOID VALVE SL2


    Lexus Gs430, Gs300. Uzs190 Grs190.A761E Automatic Transmission.Electronic Controlled Automatic Transmission System. Dtc P0766 Shift Solenoid D Performance (Shift Solenoid Valve S4)

  1. Remove the shift solenoid valve SL2.

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

    Resistance:
    Tester Connection
    		Specified Condition
    20°C (68°F)
    1 - 2
    		5.0 to 5.6 Ω

  1. Connect the positive (+) lead with a 21 W bulb to terminal 2 and the negative (-) lead to terminal 1 of the solenoid valve connector, then check the movement of the valve.

    OK:
    The solenoid makes an operating sound.


NG
REPLACE SHIFT SOLENOID VALVE SL2
OK


4.INSPECT SHIFT SOLENOID VALVE SLT


    Lexus Gs430, Gs300. Uzs190 Grs190.A761E Automatic Transmission.Electronic Controlled Automatic Transmission System. Dtc P0766 Shift Solenoid D Performance (Shift Solenoid Valve S4)

  1. Remove the shift solenoid valve SLT.

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

    Resistance:
    Tester Connection
    		Specified Condition
    20°C (68°F)
    1 - 2
    		5.0 to 5.6 Ω

  1. Connect the positive (+) lead with a 21 W bulb to terminal 2 and the negative (-) lead to terminal 1 of the solenoid valve connector, then check the movement of the valve.

    OK:
    The solenoid makes an operating sound.


NG
REPLACE SHIFT SOLENOID VALVE SLT
OK


5.INSPECT 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