How do these items fit together?

I just got done looking at a list of ecm/pcm info. I have been paying attention closely to 16197427 and 16196395. I have always known them to be with the $0D definition. Now I have come across that they could also be using $0DA, $0E, $31, and $63.

I was always under the impression it was a lock, one definition choice per service id tag. Can there have more than one def.?

 

Yup.

Just as an example, for the 1227730 ECM, IIRC GM used $8D, $8F, $5F, $88, and $3A, depending on the application. And the '86-'89 TPI cars progressed from $32, to $32B, and then to $6E, all on the 1227165 ECM.

 

So, how do you know what you have, or does it not matter? A box will run off of all the masks?

 

a 'mask' is:
what other people would call 'operating binary code',
or not

 

Or not.

Code is code.

The "mask" is how the code is arranged, as to where certain constants, tables, etc. are located.

A "definintion file" is something developed outside of GM, (i.e. the DIY community) that allows you to edit code of a certain mask with an aftermarket or homemade editing program. Examples being the .ecu or .xdf files used with tunerpro, or the .tdf files used with tunercat.

You can often interchange masks between ECMs that are closely related to each other, but it's by no means universal, since the hardware that the code is expecting to access or control may or may not be present on a different ECM. For example, you can easily run OEM '749 code on a '730, or vise versa, but don't expect to simply load stock TPI code into a TBI ECM and have it work.

As for how to tell what you have, look for the 4-letter "broadcast code" sticker on your EPROM or MEMCAL. Also, if you open the bin file with a hex editor, the mask ID is normally found within the first few bytes of code.

 

Thing is, I was going to buy a box from a used parts lot. I have been working with certain stuff and these guys won't know if it is what I am needing or not. Unless I can get my hands on it and take it apart to play around with it, I can't bother with it. Of course they won't let you do any of that until you own it.

 

So what are code are you trying to run, and on what application?

From the way the file folders are organized on the GMECM FTP server, leads me to believe that the 16156930, 16197427, and 16196395 PCMs can run $0D, $0E, and $31.

 

You also have to watch which tranny (if an auto) is in use, since things vary between the 4L6E, and 4L8E.
31 or 0E, are considered heavy Duty appls, while the 0D is light, according to some of Doc's notes.

 

Most places won't let you open and ecm.
So you decide what you want based on ecm or bcc. And then buy the appropriate ecm. If your lucky, you can find an ecm for the engine you want so you don't have to buy a memcal.