Automatic Transmission System Pattern Select Switch Snow Mode Circuit

Transmission. Lexus Is250, Is220D. Gse20 Ale20
A960E Automatic Transmission. Lexus Is250, Is220D. Gse20 Ale20

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

DRIVING TEST

CHECK HARNESS AND CONNECTOR (PATTERN SELECT SWITCH ASSEMBLY - BODY GROUND)

INSPECT PATTERN SELECT SWITCH ASSEMBLY

CHECK HARNESS AND CONNECTOR (PATTERN SELECT SWITCH ASSEMBLY - MAIN BODY ECU)

AUTOMATIC TRANSMISSION SYSTEM - Pattern Select Switch Snow Mode Circuit


DESCRIPTION

Cowl side J/B ECU receives pattern select switch information, and sends it through the multiplex communication system and CAN system to the ECM.
ECT SNOW is the system that operates the throttle motor to control engine output to reduce skidding of the driving wheels, guarantee takeoff acceleration, driving straightness and turning stability.

WIRING DIAGRAM


Lexus Is250, Is220D. Gse20 Ale20.A960E Automatic Transmission.Automatic Transmission System.Automatic Transmission System Pattern Select Switch Snow Mode Circuit

HINT:
(*) Pattern Select Switch (ECT SNOW Switch)
When the ECT SNOW switch is pushed, the switch contact is made and the ECT SNOW mode is selected.
To cancel the ECT SNOW mode, push the ECT SNOW switch once again.
The ECT SNOW mode is automatically cancelled out when the ignition switch is turned "OFF".

INSPECTION PROCEDURE

1.DRIVING TEST

  1. Start the engine.

  1. Turn the ECT SNOW switch "OFF" (Normal drive mode).

  1. Confirm vehicle response by driving from a parked position to fully depressing the accelerator pedal.

  1. Turn the ECT SNOW switch "ON" and perform the same check as above.
    Confirm that there is a difference between ECT SNOW switch "ON" and "OFF".

    HINT:
    1. Driving test should be done on a paved road (a nonskid road).
    2. Make sure not to use the TRAC system when testing a vehicle equipped with one.
    OK:
    There is a difference in acceleration between "ON" and "OFF".


NG
Go to step 2
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

2.CHECK HARNESS AND CONNECTOR (PATTERN SELECT SWITCH ASSEMBLY - BODY GROUND)

  1. Disconnect the connector of pattern select switch.



    Lexus Is250, Is220D. Gse20 Ale20.A960E Automatic Transmission.Automatic Transmission System.Automatic Transmission System Pattern Select Switch Snow Mode Circuit

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

    Standard resistance:
    Tester Connection
    		Specified Condition
    3 - Body ground
    		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3.INSPECT PATTERN SELECT SWITCH ASSEMBLY


    Lexus Is250, Is220D. Gse20 Ale20.A960E Automatic Transmission.Automatic Transmission System.Automatic Transmission System Pattern Select Switch Snow Mode Circuit

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

    Standard resistance:
    Switch Condition
    		Tester Connection
    		Specified Condition
    Press continuously Pattern select switch
    (SNOW)
    		1 - 3
    		Below 1 Ω
    Release Pattern select switch
    (SNOW)
    		↑
    		10 kΩ or higher


NG
REPLACE PATTERN SELECT SWITCH ASSEMBLY
OK


4.CHECK HARNESS AND CONNECTOR (PATTERN SELECT SWITCH ASSEMBLY - MAIN BODY ECU)


    Lexus Is250, Is220D. Gse20 Ale20.A960E Automatic Transmission.Automatic Transmission System.Automatic Transmission System Pattern Select Switch Snow Mode Circuit

  1. Connect the connector of pattern select switch.

  1. Disconnect the cowl side junction block (main body ECU RH) connector.

  1. Measure the resistance between terminal SNOW of the cowl side junction block (main body ECU RH) and body ground.

    Standard resistance:
    Switch Condition
    		Tester Connection
    		Specified Condition
    Press continuously Pattern select switch
    (SNOW)
    		J75-17 (SNOW) - Body ground
    		Below 1 Ω
    Release Pattern select switch
    (SNOW)
    		↑
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE