multiple ecu

[BBCCARGUY]

Hello all, I have tried to search about my topic and haven't really found anything on it so if I'm out of sorts send me to the correct post please. I have a 2003 Silverado 5.3 l and I have picked up an ecu for a 2003 avalanche and 2005 avalanche. Went to the yard and found a harness that someone has already cut on and cut off the ecu plugs and made my own little harness so I could program in the house. My thought was to try to use one of the avalanche ecus to program and then plug into the truck give it a good run or two if things go wrong I could plug my original back in go back home do some more programming then try it again. My question is has anyone done it this way and what other things of the truck may or may not work correctly..... like locks, power windows, radio etc..... any info would be great thanks....

[Stuffs]

it takes less than a minute to write a calibration, I bet that a lot less than swapping pcms.. and you will save 2 credits

[BBCCARGUY]

Ok.... sorry for the lack of info making everyone to assume I would be programming both pcms I wont be saving any credits, nor saving or taking more time, this is for the learning part of tuning and prepping the pcm for the vehicle it will end up in. Instead of waiting until the project is done it will give me some knowledge and know how before hand. That way I know the tune will be optimized for a good test run and ready for fine tuning when everything else is not needing my attention.

[Markmx6]

Maybe I am misunderstanding what you are looking for in the long run but, you can modify a program without being hooked up to the ECM. You have your tune saved on your computer, take it inside modify what you want and then when you go back out to the vehicle you do a "write calibration" (about a minute) and if you don't like it you load the previous tune and do another "write calibration"

The actual need to remove and replace ECMs seems like overkill to me. You can do everything you are saying using only one ECM and multiple "tunes" (also for one ECM you only need one license even though you have multiple tunes)

[Hotwire]

This and the ECMs have redundant memory, so if something happens during the flash process it has the older tune backed up in memory so you're never left walking.

[BBCCARGUY]

I think my explanation is misleading...... I have a Silverado (daily driver), I DONT want to mess with at this current point in time. I also have another pcm from another Silverado for a box chevy that I am restoring and installing a 5.3 into. I want to program the one for the project using my daily driver so I can see the results and play around with until the restoration is done. By then I will have SOME tuning knowledge (minimal) but will be able to fine tune the pcm for the truck at that time. And what I was trying to find out is will my daily driver still function (all the accessories) with another pcm while I'm playing around with it plugged and learning, tuning, etc.?

[Markmx6]

Ok, I see. I did misunderstand your intentions

I would imagine you can do that without any issues, I can't see any reason it wouldn't work, but I can't say for sure

[Hotwire]

You might have issues w/ passlock/vats with the other ecm. I know on my blazer when I swapped to a different vin it locked the radio and I had to relearn vats.