Lexus IS250 · Service Manual TRANSMISSION

Pattern Select Switch Power Mode Circuit

Circuit diagnosis

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.
The ECM memory contains the programs for the NORMAL and POWER shift patterns and lock-up pattern.
By following the programs corresponding to the signals from the pattern select switch, the neutral start and other various sensors, the ECM switches the solenoid valves ON and OFF, and controls the transmission gear change and the lock-up clutch operation.

WIRING DIAGRAM

C126191E02

INSPECTION PROCEDURE


1. CHECK HARNESS AND CONNECTOR (PATTERN SELECT SWITCH ASSEMBLY - BODY GROUND)
  1. Disconnect the connector of pattern select switch.

  1. C106209E14
    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


2. INSPECT PATTERN SELECT SWITCH ASSEMBLY

  1. C110587E14
    Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Switch Condition
    Tester Connection
    Specified Condition
    Pattern select switch
    (PWR)
    3 - 7
    Below 1 Ω
    Pattern select switch
    (NORM)

    10 kΩ or higher



NG
REPLACE PATTERN SELECT SWITCH ASSEMBLY
OK


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

  1. C110347E11
    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 PWR of the cowl side junction block (main body ECU RH) and body ground.

    Standard resistance:
    Switch Condition
    Tester Connection
    Specified Condition
    Pattern select switch
    (PWR)
    J75 - 18 (PWR) - Body ground
    Below 1 Ω
    Pattern select switch
    (NORM)

    10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE


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