Lexus IS250 · Service Manual BODY ELECTRICAL

74-40

Diagnostic trouble codes

DESCRIPTION

DTC No.
 DTC Detection Condition
 Trouble Area
74-40
 A short is detected in the speaker output circuit.
  1. Wire harness
  2. Speaker
  3. Stereo component amplifier
This circuit has a fail-safe function.
  1. When a short in the speaker circuit is detected, all sound output is stopped.

WIRING DIAGRAM

E121251E02
E121252E02
E121253E01

INSPECTION PROCEDURE

HINT:
After the inspection is completed, clear the DTCs.


1. INSPECT STEREO COMPONENT AMPLIFIER

  1. Disconnect the stereo amplifier connectors P29 and P28.

  1. Clear the DTCs and recheck for DTCs.

  1. Check if DTC 74-40 is output.

    OK:
    DTC 74-40 is not output.



 NG
REPLACE STEREO COMPONENT AMPLIFIER
OK


2. CHECK OPERATION

  1. Reconnect the stereo component amplifier connector P29.

  1. Check if DTC 74-40 is output.

    OK:
    DTC 74-40 is not output.



 NG
Go to step 14
OK


3. CHECK HARNESS AND CONNECTOR

  1. E124117E06
    Disconnect the connectors shown in the illustration from the stereo component amplifier and speakers.

  1. E121255E06
    Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester connection
    		 Condition
    		 Specified condition
    CTR+ - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    CTR- - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    ML+ - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    ML- - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    O4-2 - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    O4-4 - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    MR+ - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    MR- - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    N4-2 - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    N4-4 - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    SL+ - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    SL- - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    SR+ - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    SR- - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    WFL+ - Body ground
    		 Always
    		 10 kΩ or higher
    WFL- - Body ground
    		 Always
    		 10 kΩ or higher
    WF2+ - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    WF2- - Body ground (*2)
    		 Always
    		 10 kΩ or higher
    WF1+ - Body ground
    		 Always
    		 10 kΩ or higher
    WF1- - Body ground
    		 Always
    		 10 kΩ or higher

    *1: with Front Center Speaker*2: without Front Center Speaker



 NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4. INSPECT FRONT NO. 1 SPEAKER (LEFT HAND)

  1. Resistance check.

    1. Measure the resistance between the terminals of the speaker.

      Standard resistance:
      with Front Center Speaker:
      6 to 10 Ω
      without Front Center Speaker:
      Approximately 4 Ω



 NG
REPLACE FRONT NO. 1 SPEAKER (LEFT HAND)
OK


5. CONFIRM MODEL

Result:
Result
 Proceed to
without Front Center Speaker
 A
with Front Center Speaker
 B



B
Go to step 10
A


6. INSPECT REAR NO. 2 SPEAKER (RIGHT HAND)

  1. Reconnect the stereo component amplifier connector and rear No. 2 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE REAR NO. 2 SPEAKER (RIGHT HAND)
OK


7. INSPECT REAR NO. 2 SPEAKER (LEFT HAND)

  1. Reconnect the stereo component amplifier connector and rear No. 2 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE REAR NO. 2 SPEAKER (LEFT HAND)
OK


8. INSPECT REAR NO. 3 SPEAKER (RIGHT HAND)

  1. Reconnect the stereo component amplifier connector and rear No. 3 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE REAR NO. 3 SPEAKER (RIGHT HAND)
OK


9. INSPECT REAR NO. 3 SPEAKER (LEFT HAND)

  1. Reconnect the stereo component amplifier connector and rear No. 3 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 OK
Go to step 13
NG

REPLACE REAR NO. 3 SPEAKER (LEFT HAND)

10. INSPECT REAR STEREO COMPONENT SPEAKER (LEFT HAND)

  1. Reconnect the stereo component amplifier connector and rear stereo component speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE REAR STEREO COMPONENT SPEAKER (LEFT HAND)
OK


11. INSPECT REAR STEREO COMPONENT SPEAKER (RIGHT HAND)

  1. Reconnect the stereo component amplifier connector and rear stereo component speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE REAR STEREO COMPONENT SPEAKER (RIGHT HAND)
OK


12. INSPECT FRONT STEREO COMPONENT SPEAKER

  1. Resistance check.

    1. Measure the resistance between the terminals of the speaker.

      Standard resistance:
      7 to 9 Ω



 NG
REPLACE FRONT STEREO COMPONENT SPEAKER
OK


13. INSPECT WOOFER BOX SPEAKER

  1. E120044
    Resistance check.

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

    NOTICE:
    The speaker should not be removed for checking.


    Standard resistance:
    with Front Center Speaker:
    Tester connection
    		 Condition
    		 Specified condition
    3 - 4
    		 Always
    		 7 to 8.6 Ω
    without Front Center Speaker:
    Tester connection
    		 Condition
    		 Specified condition
    1 - 3
    		 Always
    		 Approximately 2 Ω
    2 - 4
    		 Always
    		 Approximately 2 Ω



NG
REPLACE WOOFER BOX SPEAKER
OK


14. CHECK HARNESS AND CONNECTOR

  1. E124119E02
    Disconnect the connectors shown in the illustration from the stereo component amplifier and speakers.

  1. E124118E02
    Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester connection
    		 Condition
    		 Specified condition
    FL+ - Body ground
    		 Always
    		 10 kΩ or higher
    FL- - Body ground
    		 Always
    		 10 kΩ or higher
    M4-2 - Body ground
    		 Always
    		 10 kΩ or higher
    M4-4 - Body ground
    		 Always
    		 10 kΩ or higher
    FR+ - Body ground
    		 Always
    		 10 kΩ or higher
    FR- - Body ground
    		 Always
    		 10 kΩ or higher
    L2-2 - Body ground
    		 Always
    		 10 kΩ or higher
    L2-4 - Body ground
    		 Always
    		 10 kΩ or higher
    RL+ - Body ground
    		 Always
    		 10 kΩ or higher
    RL- - Body ground
    		 Always
    		 10 kΩ or higher
    O5-2 - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    O5-4 - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    RR+ - Body ground
    		 Always
    		 10 kΩ or higher
    RR- - Body ground
    		 Always
    		 10 kΩ or higher
    N5-2 - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    N5-4 - Body ground (*1)
    		 Always
    		 10 kΩ or higher
    WFR+ - Body ground
    		 Always
    		 10 kΩ or higher
    WFR- - Body ground
    		 Always
    		 10 kΩ or higher

    *1: with Front Center Speaker



 NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


15. INSPECT FRONT NO. 1 SPEAKER (RIGHT HAND)

  1. Resistance check.

    1. Measure the resistance between the terminals of the speaker.

      Standard resistance:
      with Front Center Speaker:
      6 to 10 Ω
      without Front Center Speaker:
      Approximately 4 Ω



 NG
REPLACE FRONT NO. 1 SPEAKER (RIGHT HAND)
OK


16. INSPECT FRONT NO. 2 SPEAKER (RIGHT HAND)

  1. Reconnect the stereo component amplifier connector and front No. 2 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE FRONT NO. 2 SPEAKER (RIGHT HAND)
OK


17. INSPECT FRONT NO. 2 SPEAKER (LEFT HAND)

  1. Reconnect the stereo component amplifier connector and front No. 2 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE FRONT NO. 2 SPEAKER (LEFT HAND)
OK


18. INSPECT FRONT NO. 3 SPEAKER (RIGHT HAND)

  1. Reconnect the stereo component amplifier connector and front No. 3 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE FRONT NO. 3 SPEAKER (RIGHT HAND)
OK


19. INSPECT FRONT NO. 3 SPEAKER (LEFT HAND)

  1. Reconnect the stereo component amplifier connector and front No. 3 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE FRONT NO. 3 SPEAKER (LEFT HAND)
OK


20. CONFIRM MODEL

Result:
Result
 Proceed to
with Front Center Speaker
 A
without Front Center Speaker
 B



B
Go to step 24
A


21. INSPECT REAR NO. 2 SPEAKER (RIGHT HAND)

  1. Reconnect the stereo component amplifier connector and rear No. 2 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE REAR NO. 2 SPEAKER (RIGHT HAND)
OK


22. INSPECT REAR NO. 2 SPEAKER (LEFT HAND)

  1. Reconnect the stereo component amplifier connector and rear No. 2 speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE REAR NO. 2 SPEAKER (LEFT HAND)
OK


23. INSPECT REAR SPEAKER (RIGHT HAND)

  1. Reconnect the stereo component amplifier connector and rear speaker connector.

  1. Check that audio sound can be heard from the speaker.

    OK:
    Audio sound can be heard.



 NG
REPLACE REAR SPEAKER (RIGHT HAND)
OK

REPLACE REAR SPEAKER (LEFT HAND)

24. INSPECT REAR SPEAKER (LEFT HAND)

  1. Resistance check.

    1. Measure the resistance between the terminals of the speaker.

      Standard resistance:
      Approximately 4 Ω



 NG
REPLACE REAR SPEAKER (LEFT HAND)
OK

REPLACE REAR SPEAKER (RIGHT HAND)


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