DTC B28DF: Defroster Thermistor Circuit

DTC detecting condition:

When the stereo camera detected defogging thermistor circuit abnormality.

Trouble symptom:

The heater does not operate.

Wiring diagram:

EyeSight system Ref. to WIRING SYSTEM>EYESIGHT SYSTEM>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

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

CHECK HEATER UNIT .
1. Disconnect the connector from the heater.
2. Check the heater. Ref. to EYESIGHT>LENS HOOD>INSPECTION
Is the check result OK?

Yes : Go to 2.

No : Replace the heater. Ref. to EYESIGHT>LENS HOOD

And then, Go to 5.
CHECK HARNESS (OPEN CIRCUIT) .
1. Disconnect the connector from the stereo camera.
2. Using a tester, measure the resistance between the stereo camera connector and the heater connector.
  Connector & terminal
  
  (Rf21) No. 12 - (Rf47) No. 4:
  
  (Rf21) No. 24 - (Rf47) No. 5:
Is the resistance less than 1 Ω?

Yes : Go to 3.

No : Repair or replace the harness.

And then, Go to 3.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
Using a tester, measure the resistance between stereo camera connector and chassis ground.

Connector & terminal

(Rf21) No. 12 - Chassis ground:

(Rf21) No. 24 - Chassis ground:

Is the resistance 1 MΩ or more?

Yes : Go to 4.

No : Repair or replace the harness.

And then, Go to 4.
CHECK HARNESS (SHORT CIRCUIT TO POWER SUPPLY) .
Using a tester, measure the voltage between stereo camera connector and chassis ground.

Connector & terminal

(Rf21) No. 12 (+) - Chassis ground (-):

(Rf21) No. 24 (+) - Chassis ground (-):

Is the voltage less than 1 V?

Yes : Go to 5.

No : Repair or replace the harness.

And then, Go to 5.
CHECK DTC .
1. Connect the disconnected connectors.
2. Turn the ignition switch to OFF.
3. Turn the ignition switch to ON.
4. Read the DTC of [EyeSight] using the Subaru Select Monitor. Ref. to EYESIGHT (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)
Is DTC B28DF displayed? (Current code)

Yes : Replace the stereo camera. Ref. to EYESIGHT>STEREO CAMERA

And then, Go to 3.

No : Currently, it is normal. Finish the diagnosis.