how do i change operating system in 2003 pcm

[supershift67]

I was not able to do a cos with my 2007 controller so I went to the junkyard and bought a 2003 pcm from a 5.3 tahoe with the gas pedal and tac module. I have a lq4 with a 4l80e . I need to change my os from 12593058 to 12579405 since it has a 4l80 segment swap available and the original os does not. My question is how do I change to the 12579405 os so I can make sure the accelerator pedal works ok before I upgrade to a cos. I need an idea of where to start.

[joecar]

The OS has to be compatible with the PCM...

the 2007 PCM would be a 1MB, whereas the 2003 would be a 512KB or 768KB... i.e. the OS's that cxan run on each are not compatible.

Before I go any further, I have to look up some OS id's (hard to do on my mobile).

[supershift67]

The OS has to be compatible with the PCM...

the 2007 PCM would be a 1MB, whereas the 2003 would be a 512KB or 768KB... i.e. the OS's that cxan run on each are not compatible.

Before I go any further, I have to look up some OS id's (hard to do on my mobile).

I am planning on running the 2003 pcm instead of the 2007. I also have 2003 dbw pedal and tac module. I have a 2003 pcm that has os 12593058 and I would like to install os 12579405 on the 2003 pcm so I can eventually use a cos 031500xx.I need to be able to run a cos and 4l80e with it. I would not be running the 2007 pcm at all anymore just the 2003. thanks

[supershift67]

Unless you know what kind of vehicle I should get a different pcm out of that would be better that what I have??

[DURAtotheMAX]

The OS has to be compatible with the PCM...

the 2007 PCM would be a 1MB, whereas the 2003 would be a 512KB or 768KB... i.e. the OS's that cxan run on each are not compatible.

Before I go any further, I have to look up some OS id's (hard to do on my mobile).

2003 was 1mb flash....all 2003-2007 LS1 PCM's are 1mb flash.

99-02 was 512k

[joecar]

You're probably correct...

What year were the 768K PCM's...?

[DURAtotheMAX]

You're probably correct... What year were the 768K PCM's...?

for LS1? Never......

[supershift67]

I figured it out. I didnt realize I could just take another tune file and just flash it in my controller even though it has a different vin number. Now I just need to figure out how to find the cos tune files.

[joecar]

The empty LS1B COS files are in your C:\Users\<you>\Documents\EFILive\V7.5\Bins\Custom OS folder.