Check For Short To Ground (Power Unit Can)

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

Wiring diagram:

CAN communication system Ref. to WIRING SYSTEM>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

NOTE:

Main wiring harness or related lines may be shorted to ground, or shorted to ground in one of the control modules.

CHECK BETWEEN RELATED LINES AND MAIN WIRING HARNESS .
1. Turn the ignition switch to OFF.
2. Disconnect the central gateway control module connector.
3. Using a tester, measure the resistance between the central gateway control module connector and chassis ground.
  Connector & terminal
  
  (i88) No. 23 - Chassis ground:
  
  (i88) No. 24 - Chassis ground:
Is the resistance less than 10 Ω?

Yes : Go to 2.

No : Go to 3.
CHECK CONTROL MODULE .
With a tester connected, disconnect control modules in order.

Connector & terminal

(i88) No. 23 - Chassis ground:

(i88) No. 24 - Chassis ground:

Did the resistance change to 10 Ω or more?

Yes : Replace the control module whose resistance has changed.

No : Repair or replace the short circuit of the main wiring harness or related lines between the central gateway control module and ECM.
CHECK CENTRAL gateway control module .
1. Connect the central gateway control module connector.
2. Disconnect the VDC Control Module connector.
3. Using a tester, measure the resistance between the VDC Control Module connector and chassis ground.
  Connector & terminal
  
  (B66) No. 5 - Chassis ground:
  
  (B66) No. 19 - Chassis ground:
Is the resistance less than 10 Ω?

Yes : Replace the central gateway control module. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>CENTRAL gateway control module

No : Currently, it is normal.