Lexus IS250 · Service Manual CRUISE CONTROL SYSTEM

Cruise Control Switch Circuit

Circuit diagnosis

DESCRIPTION

The cruise control main switch operates 8 functions: SET, -(COAST), TAP-DOWN, RES (RESUME), + (ACCEL), TAP-UP, CANCEL, and MODE. The SET, TAP-DOWN, and - (COAST) functions, and the RES (RESUME), TAP-UP, and + (ACCEL) functions are operated with the same switch. The cruise control main switch is an automatic return type switch which turns on only while operating it in the direction of each arrow and turns off after releasing it. The internal contact point of the cruise control main switch is turned on with the switch operation. The ECM then reads the voltage value that has been changed by the switch operation to control MODE, SET, - (COAST), RES (RESUME), + (ACCEL), and CANCEL. The dynamic radar cruise control system has two cruise control modes: the constant speed control mode and vehicle-to-vehicle distance control mode.
  1. The vehicle-to-vehicle distance control mode is always selected when starting up the dynamic radar cruise control system.
  2. The operation of the constant speed control mode is the same as that for a conventional cruise control system.

WIRING DIAGRAM

E106784E02

INSPECTION PROCEDURE


1. READ VALUE ON INTELLIGENT TESTER
E117754E06

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG) and turn the intelligent tester main switch on.

  1. Check the DATA LIST for proper functioning of the cruise control main switch.

    ECM (Cruise control): 
    Item
    		 Measurement Item / Display (Range)
    		 Normal Condition
    		 Diagnostic Note
    MAIN SW (MAIN)
    		 Main switch signal (Main CPU) / ON or OFF
    		 ON: Main switch ON (Pushed on)
    OFF: Main switch OFF (Pushed off)
    		 -
    CANCEL SW
    		 CANCEL switch signal / ON or OFF
    		 ON: CANCEL switch ON
    OFF: CANCEL switch OFF
    		 -
    SET/COAST SW
    		 SET/COAST switch signal / ON or OFF
    		 ON: - (COAST)/SET switch ON
    OFF: - (COAST)/SET switch OFF
    		 -
    RES/ACC SW
    		 RES/ACC switch signal / ON or OFF
    		 ON: + (ACCEL)/RES (RESUME) switch ON
    OFF: + (ACCEL)/RES (RESUME) switch OFF
    		 -

    OK:
    When the cruise control main switch is operated, the display changes as shown above.

    Result: 
    Result
    		 Proceed to
    OK
    		 A
    NG (all items are defective)
    		 B
    NG (1 to 3 items are defective)
    		 C



A
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

C
REPLACE CRUISE CONTROL MAIN SWITCH
B


2. INSPECT CRUISE CONTROL MAIN SWITCH

  1. Disconnect the cruise control main switch connector.E107856E03

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


Standard resistance:
Tester Connection
 Switch Condition
 Specified Condition
A-1 (ECC) - A-2 (R/N), A-1 (ECC) - A-3 (CCS)
 Neutral
 10 kΩ or higher
A-1 (ECC) - A-3 (CCS)
 + (ACCEL)/RES (RESUME)
 216 to 264 Ω
A-1 (ECC) - A-3 (CCS)
 - (COAST)/SET
 567 to 693 Ω
A-1 (ECC) - A-3 (CCS)
 CANCEL
 1,386 to 1,694 Ω
A-1 (ECC) - A-3 (CCS)
 Main Switch off
 10 kΩ or higher
A-1 (ECC) - A-3 (CCS)
 Main Switch on
 Below 1 Ω
A-1 (ECC) - A-2 (R/N)
 Main Switch on and MODE Switch on
 Below 1 Ω



NG
REPLACE CRUISE CONTROL MAIN SWITCH
OK


3. INSPECT SPIRAL CABLE

NOTICE:
The spiral cable is an important part of the SRS airbag system. Incorrect removal or installation of the spiral cable may prevent the airbag from deploying. Be sure to read the page shown in the brackets.

HINT:
  1. Removal (Click here)
  2. Installation (Click here)

  1. E106780E12
    Remove the spiral cable.

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

    Standard resistance 
    Tester Condition
    		 Spiral Cable Position
    		 Specified Condition
    m1-1 - J24-7
    		 Center
    		 Below 1 Ω
    2.5 rotations to the left
    2.5 rotation to the right
    m1-3 - J24-1
    		 Center
    		 Below 1 Ω
    2.5 rotation to the left
    2.5 rotation to the right
    m1-4 - J24-2
    		 Center
    		 Below 1 Ω
    2.5 rotation to the left
    2.5 rotation to the right

    HINT:
    The spiral cable makes a maximum of approximately 5 rotations.



 NG
REPLACE SPIRAL CABLE
OK


4. CHECK WIRE HARNESS (SPIRAL CABLE - ECM)

  1. E117748E01
    Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    J24-1 - A6-31 (CCS)
    		 Always
    		 Below 1 Ω
    J24-7 - A5-20 (CCHG)
    		 Always
    		 Below 1 Ω
    J24-1 - Body ground
    		 Always
    		 10 kΩ or higher
    J24-7 - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


5. CHECK WIRE HARNESS (SPIRAL CABLE - BODY GROUND)
E107092E07

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    J24-2 - Body ground
    		 Always
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE


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