DTC B1244: Light Sensor Circuit

DTC detecting condition:

Auto light sensor power supply ON and auto light sensor illumination < 30 Hz (≈0.33 s) continues for 5s.

Trouble symptom:

Auto light function stops.

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to BODY CONTROL (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .

Wiring diagram:

Headlight system Ref. to WIRING SYSTEM>HEADLIGHT SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CHECK DATA MONITOR .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Body Control]. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .
  - Illumination Rate Info
3. When the lighting switch is set to AUTO, and you cover the auto light sensor with something that doesn't let light through and then expose it, inspect if the number for the Illumination Rate Info changes within the displayed range.
Does the data change within 0 - 65535?

Yes: Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.

No: Go to 2.
CHECK HARNESS (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from body integrated unit.
3. Disconnect the connector from the auto light sensor.
4. Using a tester, measure the resistance between the body integrated unit connector and auto light sensor connector.
  Connector & terminal
  
  (i362) No. 13 - (i159) No. 6:
  
  (i362) No. 14 - (i159) No. 4:
  
  (i362) No. 15 - (i159) No. 3:
Is the resistance less than 1 Ω?

Yes: Go to 3.

No: Repair or replace the open circuit of harness.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
Measure the resistance between body integrated unit connector and chassis ground using tester.

Connector & terminal

(i362) No. 13 - Chassis ground:

(i362) No. 14 - Chassis ground:

(i362) No. 15 - Chassis ground:

Is the resistance 10 kΩ or more?

Yes: Go to 4.

No: Repair or replace the short circuit of the harness.
CHECK BODY INTEGRATED UNIT .
1. Connect the connector of body integrated unit.
2. Turn the ignition switch to ON.
3. Measure the voltage between body integrated unit connector and chassis ground using tester.
  Connector & terminal
  
  (i362) No. 15 (+) - (i362) No. 13 (-):
Is the voltage 10 V or more?

Yes: Go to 5.

No: Replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .
CHECK AUTO LIGHT SENSOR .
Check the auto light sensor unit. Ref. to LIGHTING SYSTEM>LIGHT CONTROL SENSOR>INSPECTION .

Is the auto light sensor OK?

Yes: Replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .

No: Replace the auto light sensor. Ref. to LIGHTING SYSTEM>LIGHT CONTROL SENSOR .