can an ecm be bad if you are getting a code 12
and no other codes

Yes , it can have bad soldered joints, corroded or cracked circuit boards. Older GM pcms were commonly bad, not passing ghte " tap" rest.

Code 12 is "I'm in diagnostic mode, thank you"
Unless your SES light is spazzing and/or on before you check the codes, its all normal.
(the ECM repeats each code three times before moving to the next, you know)

YEs it can. Technically, a code 12 means no distributor/spark reference signal. When you're doing a key on/engine off diagnostic, it's telling you the engine isn't running (duh). It's been a universal "system check" since the dawn of OBD1, but in actuality, it's only telling you there's no spark signal.

Check your ECM service number. If it's 1227727, it's more than likely bad. W-bodies with this ECM number were known to have problems, especially 88-93 Models. Are you having intermittent no-start/stalling problems? IF not, what has you suspecting the ECM is bad?

YEs it can. Technically, a code 12 means no distributor/spark reference signal. When you're doing a key on/engine off diagnostic, it's telling you the engine isn't running (duh). It's been a universal "system check" since the dawn of OBD1, but in actuality, it's only telling you there's no spark signal.

Huh. You learn something new every day.
Though I knew that is why you get a MIL when you key on/engine off, I didn't know about ODB1 code 12 meaning the exact same.

can an ecm be bad if you are getting a code 12
and no other codes

What problems are you having with your car that you suspect the ECM is the cause?
An ECM could be bad and never display a DTC.
If it is a 1227727, give it a little tap while the engine is running..if the engine stalls, YES your ECM is bad.

What problems are you having with your car that you suspect the ECM is the cause?
An ECM could be bad and never display a DTC.
If it is a 1227727, give it a little tap while the engine is running..if the engine stalls, YES your ECM is bad.

well i was just wondering
my lumina crapped out on me
as in one of my ofther postings

i found a bad injector that time
i ordered and replaced all injectors
with reconditioned injectors
the car ran beutifully
for about a month
then it started missing

one of the injectors failed
then got another one
car runs better
but still with like a miss

i have been running injector cleaner
through the gas tank

it seems a little better some days
than others

was just wondering if it could be the ecm
but i've done the tap test thing
and there was no change

i guess it could be the injectors yet
again

why did gm do the intake manifold like they did on those 3.1 and 2.8
they should all ways give you access to injectors and or stuff like that
so you don't have to take the hole thing apart
to test things while they are running

i have also taken the ecm out of its cases and every thing looks ok
no corrosion or bad looking cercuits
i have seem a couple of real bad ones come out of a honda civic

so i don't think its the ecm
i was just wondering if any body had a problem with the ecm seemingly ok but had problems and it was the ecm