EPROM’s

[twisted60]

Are all the eprom’s compatible in the TCM’s ? I see different years I assume different programming for shift points as trucks got heavier ? I’m just trying to learn more about the different Humvee’s.
Thanks


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[Mogman]

Basically yes but for the later PCS TCMs which do not use a PROM.

Some are EPROMS and some are PROMS, the difference is the EPROMS can be erased using UV and re-programmed and a PROM is a one time use device, no difference to the end user.

I have some of the hex files and can erase and program them, I would like to build a library of the different files, then if I got really bored I could dig into the hex files and decipher the differences and even come up with custom shift points/DTCs etc.

The "major" differences are the NA and turbo chips and likely has more to do with the gearing than the weight, they may have also added or dropped what DTC codes would and would not light the trans light and possibly what actual perimeters set DTC codes and fixed any bugs as time went by.

 

[twisted60]

Thank you that helps me understand them better, I was confused by the dates on the chips. So a 1999 turbo chip is good for 2006 turbo but not for a 2006 non turbo and the newer TCM’s don’t have chips.
Again thanks


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[Coug]

NEWS | July 7, 2021
HMMWV: TCM Has Replaced EPROM


Photo by Sgt. Kristina Truluck

Mechanics, make a note that the erasable programmable read only memory (EPROM) has been replaced by the one-piece transmission control module (TCM), which is needed to operate your unit’s HMMWVs.

If you have a HMMWV that’s NMC because it needs a 2-piece EPROM and you try to order a replacement for it, your requisition is going to be rejected.

You also don’t want to order a transmission because it won’t come with an EPROM.

Send any questions you have about ordering correct parts to the HMMWV maintenance team mailbox at:

HMMWV: TCM Has Replaced EPROM

Mechanics, make a note that the erasable programmable read only memory (EPROM) has been replaced by the one-piece transmission control module (TCM), which is needed to operate your unit’s HMMWVs. ...

www.psmagazine.army.mil

 

[Coug]

Re: Which E-PROM

• Quote

Post by 86humv » Thu Aug 05, 2021 4:51 am

Here's the line up :
TCM-2100AA, AB, AC are turbo trucks.
TCM-2100BA, BB are M1097A2 NA trucks.

Which E-PROM - G503 Military Vehicle Message Forums

 

[Mogman]

Thank you that helps me understand them better, I was confused by the dates on the chips. So a 1999 turbo chip is good for 2006 turbo but not for a 2006 non turbo and the newer TCM’s don’t have chips.
Again thanks


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I have heard some swap them, I can't remember which way, IIRC they put a turbo chip in a NA truck and it shifts "better" in their opinion, but again I do suffer from CRS.
The later TCMs are crazy expensive compared to simply getting a refurb older style.

 

[twisted60]

Yes the new TCM’s are pricy $650 up. I’m going to try getting an old civi TCM with an eprom to just try ($250 +/-) if it works I’ll keep for a spare, if not … well I learned something
Thanks


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[86humv]

The trans computer in most trucks is a GM unit with a replaceable blue chip.
The TCm-2100 series is not a GM product, and has no replaceable chip....later trucks have these.
They both will plug into the box under the seat.

 

[twisted60]

Thanks, I’ve found 2 compatible GM TCM’s used and ordered the blue chips so I’ll find out, hate to pay $650 up for a spare. I’m really just trying to learn more and investing $200 is worth it to me.
Thanks everyone.
Rick


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[Mogman]

Thanks, I’ve found 2 compatible GM TCM’s used and ordered the blue chips so I’ll find out, hate to pay $650 up for a spare. I’m really just trying to learn more and investing $200 is worth it to me.
Thanks everyone.
Rick


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You can get a refurb for about the same price