Body Integrated Unit Power Supply And Ground Circuit

NOTE: For the DC power supply circuit, refer to:

Impreza model: Refer to WIRING SYSTEM (IMPREZA MODEL)>POWER SUPPLY CIRCUIT .
Crosstrek model: Refer to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>POWER SUPPLY CIRCUIT .
Crosstrek hybrid model: Refer to WIRING SYSTEM (CROSSTREK MODEL (HEV))>POWER SUPPLY CIRCUIT .

Model without Auto Start Stop

Courtesy of SUBARU OF AMERICA, INC.

Model with Auto Start Stop

Courtesy of SUBARU OF AMERICA, INC.

CHECK DTC OF BODY INTEGRATED UNIT .
Check DTC of body integrated unit. Refer to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>OPERATION .

Is the DTC of power line displayed on body integrated unit?

Yes : Repair or replace it according to the DTC.

No : Go to 2.
CHECK HARNESS BETWEEN BODY INTEGRATED UNIT AND BATTERY .
1. Turn the ignition switch to ON.
2. Measure the voltage between body integrated unit and chassis ground.
Connector & terminal

(B280) No. 1 (+) - Chassis ground (-):

(B287) No. 4 (+) - Chassis ground (-):

Is the voltage 9 - 16 V?

Yes : Go to 3.

No : Check harness for open circuit between the body integrated unit and the battery or a blown fuse.
CHECK BODY INTEGRATED UNIT IGN POWER SUPPLY CIRCUIT .
1. Turn the ignition switch to ON.
2. Measure the voltage between F/B fuse No. 5 and chassis ground.
Connector & terminal

F/B fuse No. 5 (+) - Chassis ground (-):

Is the display 10 V or more?

Yes : Go to 4.

No : Repair the open circuit of the harness between body integrated unit and ignition switch.
CHECK BODY INTEGRATED UNIT AND ACC VOLTAGE SUPPLY CIRCUIT .
1. Turn the ignition switch to ACC.
2. Measure the voltage between F/B fuse No. 9 and chassis ground.
Connector & terminal

F/B fuse No. 9 (+) - Chassis ground (-):

Is the display 10 V or more?

Yes : Go to 5.

No : Repair the open circuit of the harness between body integrated unit and ignition switch.
CHECK HARNESS BETWEEN BODY INTEGRATED UNIT AND CHASSIS GROUND .
1. Turn the ignition switch to OFF.
2. Measure the harness resistance between the body integrated unit and chassis ground.
Connector & terminal

(i84) No. 4 - Chassis ground:

(B287) No. 1 - Chassis ground:

Is the resistance less than 1 Ω?

Yes : Go to 6.

No : Repair the open circuit of harness between the body integrated unit and chassis ground.
CHECK FOR POOR CONTACT .
Is there poor contact of connector?

Yes : Repair the poor contact.

No : End.