I tried doing a Google search, but didn't come up with much for of a definitive answer.

What exactly does the ECM do when it enters limp mode? Turn electric fans on, high idle, fixed timing? What else?

I'm, trying to figure out if my ECM is shot, it doesn't prime the fuel pump, nor does it give any codes when you ground out the diagnostics wire (SES light is on constantly, electric fans run constantly), or if it is just cause I don't have a memcal installed. I am not trying to start the vehicle, just wanted to see if the ECM was hooked up correctly, and also make sure that all the sensors are sending readings that make sense.

I do have a spare ECM, but I know this one worked prior to me installing speed density, so if I did fry it, I need to know so I can hunt down what killed it.

 

Yes. If the ECM does not perform a succesful POST with ROM checksum for the MEMCAL, it goes directly to backup mode. In your case, without a MEMCAL installed, it doesn't have backup chips, so it probably won't even run.

 

Cool, I'm gonna borrow a buddy's 5.7 memcal (won't be able to start due to VATS) but that should let me know if that is infact my whole problem (which I did suspect from the start, but wanted to make sure )

 

Alright!

I went ahead and borrowed the memcal, put it in, and sure enough, everything seemed to be working correctly.

However, I did find one problem that is still there. The ECM is not delivering any ground to the fuel pump relay. I know that the wiring is good up to the ECM, as I can manually ground that pin and it immediately turns the pump on.

Does this have something to do with the VATS? Or is my ECM still fried?

 

VATS disables the fuel system if incorrect key resistance is found...

 

Perfect, thats what I wanted to hear

Now to make myself an adapter / buy one from moates so I can disable VATS, AIR and the EGR in the prom, along with telling it that it now has 19 lb/hr injectors, and see if she'll start