engine swaps, with battery
Neg lug pulled the whole time.?
- short block? 2.5L?
- long block?
- or total engine swap, all wiring , and sensor,,injectors, and all, (ALL)
causes
not connecting all connectors backup
or not moving all sensors over old to new engine,
if the IMMO lamp glows correctly way ask that, the users guide tell this on all cars. dead,stuck on, or blinks. in the manual is how.
BCM brain is not happy for sure, it runs horns and lights. and more.
same engine exactly?
to pull and engine lots of connectors can be missed or crushed.
if all is done right
and fails
pull battery
neg lug for 1 hour, and put back see if BCM resets as it well. all brain boxes resets PCM/TCM /BCM and well all do.
did you buy a dead car? and never seen he IMMO work ever you?
open glove box take out users guide and read IMMO page
IMMO page 2-5 glove box words
The security indicator light deters potential thieves by
indicating that the vehicle is equipped with an immobi-
lizer system. It begins flashing about 60 seconds after
the ignition switch is turned from the "ON" position to
the "ACC" or "LOCK" position or immediately after the
key is pulled out.
If the security indicator light does not flash, the immo-
bilizer system may be faulty. If this occurs, contact
your SUBARU dealer as soon as possible.
In case an unauthorized key is used (e.g. an imitation
key),
the security indicator light comes on.
NOTE
Even if the security indicator light flashes irregu-
larly or its fuse blows (the light does not flash if its
fuse is blown), the immobilizer system will func-
tion normally
https://www.manualslib.com/manual/232319/Subaru-2005-Forester.html?term=2-5&selected=2&page=117#manual
