So say that I had a second ECM for my car, and I wanted to exchange the stock ECM with this one, or the other way around...
Would there be any issues with the odometer reading? Any other potential issues? I heard from someone who did this that it messed up their oil life on the Onstar diagnostics. Speak of the devil, is there anything Onstar logs and/or "phones home" with regard to an ECM being exchanged?

 

mileage is stored in the BCM not PCM

Generally you have little to no worry with trading ECUs

 

So what would the odds be of a dealer being able to tell you had a different ECM on there, then changed it out with the stock one right before a warranty service visit? Again, hypothetically speaking, of course...

 

Uhh other then the fact the one sitting around stock will be almost dust and dirt free ..

just cake some dirt on it call it a day ..

The oil level is reset so make sure it doesn't say 0% oil life ...

other than that absolutely no way they could tell unless they sent it to GM and I am not even sure they could prove it without spending more money then the cars worth

 

I may or may not have 2 ecu's and I may or may not have gone in for service and nothing was found or mentioned. The onlything stored on the ecu is oil change %. So, If you keep your OEM original ecu un tuned and tune an extra you will not have any problems.

 

Haha, I keep everything under my hood spic and span clean so that would not be an issue! Both ECM's would look absolutely new! As for the oil life, is there a way to reset it to 100% ourselves? Can any oil change place do it? (haha, quickly change the oil right before the big warranty repair)


Very well said. I may or may not be very happy with your answer, and I may or may not move forward with something based on it.

 

It's in the manual. Combo sequence of return & info buttons once you show the OLM. I forget exactly. The 3 pedal presses to the floor doesn't work on the LNF.

 

My guess is they had half a brain they would put a service bulletin out to look for 100% oil life for suspected ecu swap .. It goes down to like 99 98% pretty quick but still .. LOL

 

Turn the DIC to oil life % then turn your car off. You reset it by turning the car to ON without starting it and holding info and back, when you let go of them after 5 sec, it will say oil life reset; hold reset, it will say acknowledged, the it is 100%.

I know because I did an oil change the other day and reset it on both PCMs. Drive it until it goes down 5%, since it is mileage based, then pull it out and let it sit.

If you go in for some simple and common warranty work, they would most like not even look into it or scan it.

And if it happens to be 100%, say you changed the oil, then it happened right after that

 

^^ this, however you don't need to set the DIC to oil % and then turn the car off. with the car running, or just the ACC's on you can follow the rest of the above instructions and bingo, 100% oil life!