ER HC, DTC C0116, Battery Light, No Start

[bigBADbenny]

So that’s not the only CAN-HS diagnostic.
B0202 might be relevant CAN-HS bus off, or perhaps another that relates to the brake light circuit, since that’s your only other DTC…
DTC B0221 CAN-HS ECM NO-RECEIVE DATA obviously ecu specific...

[CirioP]

So we might focus on the high speed canbus network, here’s a great video series that focuses on the diagnostics.
Bear in mind the age of your vehicle puts it in the midrange of canbus development, eg it’s not a single network: it has high and low speed canbus, but neither does it have a gateway module.

So we know it’s a high speed can issue, it’s the network between the ecu, bcm and abscm.
As per the video, we can use the wiring diagrams to check the layout of that canbus, see if one single fault is bringing down the house of cards.

We need to map the canbus well before doing any testing since the layout and connected modules dictate the scope of diagnostics.
In all the “er hc” posts on various Subaru forums, the issue is almost always a ground, but which one exactly?
We’ll have more clues once we map the canbus. Eg there might be specifically related grounds.
I’m looking at the second video in the series atm, plus getting to those fsm diagrams but starting with C0140 diagnostics.
https://www.youtube.com/watch?v=YbF3idCk4EQ

How detailed the video is about the diagnostics. Thank you.

[boydbino]

Thought I would jump in here with an update!

Test ECU was sent down, plugged it in and all my problems were gone.

Of course we had the IMMOB codes due to the ECU not be synced with the CANBUS however this was sent off to a competent auto electrician who is familiar with unbricking / fixing ECUs.
https://theautomotiveclinic.com.au/

They have some good videos on Instagram / Youtube / Tik Tok

They were able to find that the ECU was bricked likely due to a drop in battery voltage when being read / flashed.

They were able to swap over the immobiliser data to the new ECU that is working from the old bricked ECU.

Pending success when testing new ECU upon delivery.