Lexus IS250 · Service Manual HEATER & AIR CONDITIONING SYSTEM

Air Conditioning Compressor Magnetic Clutch Circuit

Circuit diagnosis

DESCRIPTION

The A/C amplifier sends a magnetic clutch ON command signal to the ECM through the BEAN line and CAN line. Then the ECM turns the A/C COMP relay on to turn the magnetic clutch on.

WIRING DIAGRAM

E121184E03

INSPECTION PROCEDURE


1. CHECK MULTIPLEX COMMUNICATION SYSTEM

  1. Use the intelligent tester to check if the Multiplex Communication System (MPX) is functioning normally.

    Result:
    Result
    		 Proceed to
    MPX DTC is not output
    		 A
    MPX DTC is output
    		 B



B
GO TO MULTIPLEX COMMUNICATION SYSTEM
A


2. CHECK CAN COMMUNICATION SYSTEM

  1. Use the intelligent tester to check if the CAN Communication System is functioning normally.

    Result:
    Result
    		 Proceed to
    CAN DTC is not output
    		 A
    CAN DTC is output
    		 B



B
GO TO CAN COMMUNICATION SYSTEM
A


3. READ VALUE OF INTELLIGENT TESTER

  1. Connect the intelligent tester to the DLC3.

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

  1. Turn the A/C switch on and off.

  1. Select the item below in the Data List, and read the display on the intelligent tester.

    Data List / Engine: 
    Item
    		 Measure Item
    		 Normal Condition
    		 Diagnostic Note
    A/C Signal
    (A/C Signal)
    		 A/C signal / ON or OFF
    		 ON: A/C ON
    OFF: A/C OFF
    		 -

    OK:
    The display is as specified in the normal condition column.



 NG
Go to step 12
OK


4. READ VALUE OF INTELLIGENT TESTER

  1. Connect the intelligent tester to the DLC3.

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

  1. Change the blower fan speed to LO using the blower switch.

  1. Turn the A/C switch on and off.

  1. Select the item below in the Data List, and read the display on the intelligent tester.

    Data List / Engine: 
    Item
    		 Measure Item
    		 Normal Condition
    		 Diagnostic Note
    A/C Magnetic Clutch Relay
    (A/C Magnetic Clutch Relay)
    		 A/C magnetic clutch relay / OFF, ON
    		 ON: A/C magnetic clutch ON
    OFF: A/C magnetic clutch OFF
    		 -

    OK:
    The display is as specified in the normal condition.



 NG
REPLACE ECM
OK


5. PERFORM ACTIVE TEST BY INTELLIGENT TESTER

  1. Connect the intelligent tester to the DLC3.

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

  1. Select the item below in the Active Test and read the display on the intelligent tester.

Active Test / Engine: 
Item
 Test Details / Display (Range)
 Diagnostic Note
Magnetic Clutch Relay
(A/C Mag Clutch)
 Magnetic Clutch Relay / OFF, ON
 -

OK:
The magnetic clutch operates normally.



 OK
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
NG


6. INSPECT FUSE (A/C COMP)

  1. E116909E01
    Remove the A/C COMP fuse from the engine room R/B and J/B No. 2.

  1. Measure the resistance of the fuse.

    Standard resistance:
    Tester Item
    		 Condition
    		 Specified Condition
    A/C COMP fuse
    		 Always
    		 Below 1 Ω



NG
REPLACE FUSE (A/C COMP)
OK


7. INSPECT RELAY (A/C COMP)

  1. B060778E04
    Remove the A/C COMP relay from the engine room R/B and J/B No. 2.

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

    Standard resistance:
    Tester Connection
    		 Specified Condition
    3 - 5
    		 10 kΩ or higher
    3 - 5
    		 Below 1 Ω
    (when battery voltage is applied to terminals 1 and 2)



NG
REPLACE RELAY (A/C COMP)
OK


8. INSPECT A/C COMPRESSOR

  1. E116585E01
    Disconnect the A/C compressor connector.

  1. Disconnect the magnetic clutch connector.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    E8-1 (MG+) - A-1
    		 Always
    		 Below 1 Ω
    E8-1 (MG+) - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPLACE A/C COMPRESSOR
OK


9. INSPECT MAGNETIC CLUTCH

  1. E113611E01
    Measure the resistance of the connector.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    A-1 - Body ground
    		 Always
    		 3.4 to 3.8 Ω

  1. When connector terminal A1 is connected to the positive (+) battery terminal, check that the following occurs: 1) the magnetic clutch's operating sound can be heard, and 2) the magnetic clutch's hub and rotor lock.



 NG
REPLACE MAGNETIC CLUTCH
OK


10. CHECK WIRE HARNESS (ENGINE ROOM R/B AND J/B NO. 2 - A/C COMPRESSOR)

  1. E113603
    Turn the engine switch on (IG).

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

    Standard voltage:
    Tester Connection
    		 Specified Condition
    Relay block A/C COMP relay terminal 5 - Body ground
    		 10 to 14 V
    Relay block A/C COMP relay terminal 1 - Body ground
    		 10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


11. CHECK WIRE HARNESS (ENGINE ROOM R/B AND J/B NO. 2 - ECM)
E118578E03

  1. Disconnect the ECM connector.

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

    Standard resistance:
    Tester Connection
    		 Specified Condition
    Relay block A/C COMP relay terminal 2 - A6-13 (ACMG)
    		 Below 1 Ω
    A6-13 (ACMG) - Body ground
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (A/C COMPRESSOR - ENGINE ROOM R/B AND J/B NO. 2)

12. REPLACE AIR CONDITIONING AMPLIFIER

  1. Replace the A/C amplifier with a normal one and check that the condition returns to normal.

    OK:
    Same problem does not occur.



 OK
END
NG

REPLACE ECM


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