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DTC    B1244    Light Sensor Circuit Malfunction

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DESCRIPTION

The automatic light control sensor detects ambient light, converts it into an electrical signal, and outputs it to the main body ECU (multiplex network body ECU). The main body ECU (multiplex network body ECU) turns on or off the headlights and taillights according to the signal.

DTC No.
DTC Detecting Condition
Trouble Area
B1244
  1. Malfunction in automatic light control sensor
  2. Open or short in automatic light control sensor circuit
  1. Automatic light control sensor
  2. Harness or connector
  3. Main body ECU (multiplex network body ECU)

WIRING DIAGRAM


E144299E25


INSPECTION PROCEDURE

1.READ VALUE USING INTELLIGENT TESTER

  1. Connect the intelligent tester to the DLC3.

  1. Turn the power switch on (IG).

  1. Turn the intelligent tester on.

  1. Enter the following menu items: Body / Main Body / Data List.

  1. Read the display on the intelligent tester.

    Main Body 
    Tester Display
    		Measurement Item/Range
    		Normal Condition
    		Diagnostic Note
    Illumination Rate
    		Illumination rate information/0 ms to 99.99 ms
    		Value is output according to ambient light levels
    		-

    OK:
    Normal condition listed above is displayed.



NG
Go to step 2
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) (Click here)  

2.CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - AUTOMATIC LIGHT CONTROL SENSOR)

  1. Disconnect the I1 automatic light control sensor connector.

  1. Disconnect the L7 main body ECU (multiplex network body ECU) connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L7-22 (CLTE) - I1-6 (CLTE)
    		Always
    		Below 1 Ω
    L7-21 (CLTS) - I1-4 (CLTS)
    		Always
    		Below 1 Ω
    L7-20 (CLTB) - I1-3 (CLTB)
    		Always
    		Below 1 Ω
    L7-22 (CLTE) - Body ground
    		Always
    		10 kΩ or higher
    L7-21 (CLTS) - Body ground
    		Always
    		10 kΩ or higher
    L7-20 (CLTB) - Body ground
    		Always
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3.INSPECT MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)


    E166535E04

  1. Reconnect the L7 main body ECU (multiplex network body ECU) connector.

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

    Standard Voltage:
    Tester Connection
    		 Condition
    		Specified Condition
    L7-20 (CLTB) - L7-22 (CLTE)
    		Power switch off
    		Below 1 V
    Power switch on (IG)
    		11 to 14 V

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L7-22 (CLTE) - Body ground
    		Always
    		Below 1 Ω

    Text in Illustration 
    *1
    		Component with harness connected
    (Main Body ECU (Multiplex Network Body ECU))



NG
REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) (Click here)
OK


4.INSPECT AUTOMATIC LIGHT CONTROL SENSOR


    E179216E07

  1. Reconnect the I1 automatic light control sensor connector.

  1. Connect an oscilloscope to the automatic light control sensor connector.
    Text in Illustration 
    *1
    		Component with harness connected
    (Automatic Light Control Sensor)



    B113714E01

  1. Check the waveform.

    OK:
    Tester Connection
    		Tool Setting
    		 Condition
    		Specified Condition
    I1-6 (CLTE) - I1-4 (CLTS)
    		5 V/DIV., 5 ms./DIV.
    		Power switch on (IG), light control switch in AUTO position
    		Correct waveform is as shown

    HINT:
    If the ambient light becomes brighter, width A becomes narrower.



NG
REPLACE AUTOMATIC LIGHT CONTROL SENSOR (Click here)
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) (Click here)