2008 Denali XL possible ECM Failure?

[thompsoj22]

it is a long shot but CPS gone bad? i know this sensor normally is good or bad, but it is critical to ecm rpm recognition. see if you can simply give the harness/connector a push/pull and see what happens, this is simply what id do, it sounds like you have skills, these vehicle electronics/emission controls can adjust/control the engine for effeciency 100 times per second but cant tell you what is wrong when they fail? F'ing engineers

 

[Rich Reno]

if you bought that dorman local I would consider exchanging it for another one just to rule it out, dorman is usually ok stuff but not always.

I did buy it local, but they only had one...

 

[thompsoj22]

There was some additional codes initially, the fpcm did have signs that water was in it. Before that it wasn't even powering up the pump.

was this connection coroded? its going to be somthing simple, this component changed the problem, check this harness?

 

[Mechanic421]

So do you have any way to read data on a scanner? Really need a scantool.

 

[Rich Reno]

So do you have any way to read data on a scanner? Really need a scantool.

I have an autocal, but that is what is making me think that it's the ecm, the data I'm pulling doesn't look normal across the board.

I wouldn't write off the cps, but I replaced that about 2 years ago... So I doubt it

None of the harnesses or connectors had any corrosion on them, and nothing looked scorched or miss aligned

 

[Mechanic421]

Can you post a screen shoot?

 

[Mechanic421]

I have an autocal, but that is what is making me think that it's the ecm, the data I'm pulling doesn't look normal across the board.

I wouldn't write off the cps, but I replaced that about 2 years ago... So I doubt it

None of the harnesses or connectors had any corrosion on them, and nothing looked scorched or miss aligned

Is there fuel pump duty cycle or maybe command data ?

 

[Rich Reno]

Is there fuel pump duty cycle or maybe command data ?

In efi live dvt commands there is a fuel pump duty cycle, but the dvt isn't giving any normal responses.

I'll try and mess with it again and see if I can post some screen shots

 

[Mechanic421]

So you have tried to command manually in tests/functions test and no response? Sometimes in efilive you have to have it on in two different places. I am not really all that great at computer shit but I get by. Hopefully someone smarter will chime in. But if you can command fuel pump check output at computer and go from there. Anti theft? May need to scan whole truck.

 

[Doubeleive]

just curious, how is your voltage? how old is the battery? when it runs for a minute what kind of voltage are you getting? i'm wondering when you are getting funky readings on the autocal could be voltage related. just something to consider.