Toyota Venza: Light Sensor Circuit Malfunction (B1244)

Toyota Venza Service Manual / Lighting (ext) / Lighting System / 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 (driver side junction block assembly). The main body ECU (driver side junction block assembly) turns on or off the headlights and taillights according to the signal.

DTC No.	DTC Detecting Condition	Trouble Area
B1244	Malfunction in automatic light control sensor Open or short in automatic light control sensor circuit	Automatic light control sensor Harness or connector Main body ECU (driver side junction block assembly)

WIRING DIAGRAM

PROCEDURE

1.	READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Select the following menu items: Body Electrical / Main Body / Data List.

(e) Read the display on Techstream.

Main Body

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

OK:

Normal condition listed above is displayed.

REPLACE MAIN BODY ECU (DRIVER SIDE JUNCTION BLOCK ASSEMBLY)

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

(a) Disconnect the F4 automatic light control sensor connector.

(b) Disconnect the D49 main body ECU (driver side junction block assembly) connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
D49-18 (CLTE) - F4-3 (CLTE)	Always	Below 1 Ω
D49-19 (CLTS) - F4-5 (CLTS)	Always	Below 1 Ω
D49-20 (CLTB) - F4-6 (CLTB)	Always	Below 1 Ω
D49-18 (CLTE) - Body ground	Always	10 kΩ or higher
D49-19 (CLTS) - Body ground	Always	10 kΩ or higher
D49-20 (CLTB) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	INSPECT MAIN BODY ECU (DRIVER SIDE JUNCTION BLOCK ASSEMBLY)

(a) Reconnect the D49 main body ECU (driver side junction block assembly) connector.

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

Text in Illustration

Component with harness connected

(Main Body ECU (Driver Side Junction Block Assembly))

Standard Voltage:

Tester Connection	Condition	Specified Condition
D49-20 (CLTB) - D49-18 (CLTE)	Ignition switch off	Below 1 V
D49-20 (CLTB) - D49-18 (CLTE)	Ignition switch ON	11 to 14 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
D49-18 (CLTE) - Body ground	Always	Below 1 Ω

REPLACE MAIN BODY ECU (DRIVER SIDE JUNCTION BLOCK ASSEMBLY)

4.	INSPECT AUTOMATIC LIGHT CONTROL SENSOR

(a) Reconnect the F4 automatic light control sensor connector.

(b) Connect an oscilloscope to the automatic light control sensor connector.

Text in Illustration

*1	Component with harness connected (Automatic Light Control Sensor)

OK:

Tester Connection	Tool Setting	Condition	Specified Condition
F4-3 (CLTE) - F4-5 (CLTS)	5 V/DIV., 5 ms./DIV.	Ignition switch ON, light control switch in AUTO position	Correct waveform is as shown

HINT:

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

REPLACE MAIN BODY ECU (DRIVER SIDE JUNCTION BLOCK ASSEMBLY)

REPLACE AUTOMATIC LIGHT CONTROL SENSOR

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