Lexus NX: Light Sensor Circuit Malfunction (B1244)

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 the headlights and taillights on or off according to the signal.

The main body ECU (multiplex network body ECU) outputs DTC B1244.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B1244

Light Sensor Circuit Malfunction

  • Malfunction in the automatic light control sensor.
  • Open or short in the automatic light control sensor circuit.
  • Automatic light control sensor
  • Main body ECU (multiplex network body ECU)
  • Harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Recognition code registration is necessary when replacing the main body ECU (multiplex network body ECU).
  • If the main body ECU (multiplex network body ECU) is replaced, refer to Registration.

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Main Body > Clear DTCs
NEXT

2.

CHECK FOR DTC

(a) Check for DTCs.

Click here

Body Electrical > Main Body > Trouble Codes
DTC B1244 output does not occur

USE SIMULATION METHOD TO CHECK

DTC B1244 output occurs

3.

READ VALUE USING TECHSTREAM (LIGHT SENSOR ILLUMINANCE)

(a) Using the Techstream, read the Data List.

Click here

Body Electrical > Main Body > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Light Sensor Illuminance

Light control sensor illuminance

0 to 17600 lx

Value is output according to ambient light level

-

Body Electrical > Main Body > Data List

Tester Display

Light Sensor Illuminance

OK:

The display is as specified in the normal condition column.

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

4.

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

(a) Disconnect the I48 main body ECU (multiplex network body ECU) connector.

(b) Disconnect the J6 automatic light control sensor connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I48-21 (CLTE) - J6-2 (CLTE)

Always

Below 1 Ω

I48-19 (CLTB) - J6-1 (CLTB)

Always

Below 1 Ω

I48-20 (CLTS) - J6-4 (CLTS)

Always

Below 1 Ω

I48-21 (CLTE) - Body ground

Always

10 kΩ or higher

I48-19 (CLTB) - Body ground

Always

10 kΩ or higher

I48-20 (CLTS) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.

CHECK MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

(a) Remove the instrument panel junction block assembly and main body ECU (multiplex network body ECU) as a unit with the connectors still connected.

Click here

*a

Component with harness connected

(Main Body ECU [Multiplex Network Body ECU])

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

I48-19 (CLTB) - I48-21 (CLTE)

Power switch off

Below 1 V

Power switch on (IG)

11 to 14 V

NG

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

OK

6.

CHECK AUTOMATIC LIGHT CONTROL SENSOR

(a) Check the automatic light control sensor.

Click here

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE AUTOMATIC LIGHT CONTROL SENSOR

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