Hello fellow Hummer lovers,

I'm looking for a little help or guidance on an issue I'm having. I have an 08 H3 and have been having sporadic issues with transmission slipping, rpms going way up or coming out of gear. I took it in and there are no issues with the transmission itself. I did a bunch of research and decided to change out the TCM - Transmission Control Module. 2008 is the first year in which the TCM is it's own module and not incorporated into the main PCM (picture attached). I ordered the part - AC Delco - and replaced the TCM. It was an easy job to replace it as the TCM location is right under the hood near the fire wall. The place I ordered it said this unit was "plug and play", however after I replaced the old with the new my hummer fired right up but I could not move the gear selector out of Park. It is just stuck in park and will not allow me to move it to reverse, neutral, drive, etc... I removed the new TCM that I just installed are put the old one back in - no issues, starts right up and I'm able to shift out of park. So I put the new one back in and I tried a couple things to have the new TCM recognized - disconnected battery for 30 minutes, did a relearn process I found where you turn key on, press accelerator for 10 seconds, turn key off and wait 10 minutes. No dice - still won't shift out of park. Put the old one back in and it shifts out of park no problem.

Anyone have any ideas here? Is there additional programming that needs to be done to recognize the new TCM? Maybe the part that was shipped to me is defective? Is it a must that a dealer program the new TCM or are there instructions out there on how I can do it myself?

I appreciate the help here! Thanks so much!

Dan

 

It is not plug and play.

Disconnecting the battery for a while on a late model GM does nothing, they use flash based memory and store the last 300 ignition cycles, power or no power. What you bought is like a blank thumb drive it has no idea what vehicle you are going to attach it to = must be programmed.

 

Thanks Doc - That's what I'm gathering as well. Called a tech to come out and flash it for me.

 

Vin programming required, did you give the seller your VIN? If not you only have a paperweight. Many available on Ebay offering programmed modules. Look here::::::::>>> PROGRAMMED Transmission Computer TCM ECU T42 24242391 24234503 24252114

 

Thanks Hummerz - Got it and appreciate the reply.

 

Just return the other "not as described" for a full refund. The seller above has an excellent sales history and you will get the tcm with all available updates, for less than it cost for programming local. I retired 6yrs ago, back then module programming was $100-$150 cost to the customer. Update when you install it and make sure you have clean dex vi fluid to the full mark on the indicator.

 

I just dropped off the FedEx package on its way back to seller and they agreed to full refund which was really nice. Ordering another one and gave them the VIN number for preprogramming. Thanks again all!

 

I had reached out to one of our local companies that has a mobile auto flashing service before I returned the product and he quoted me a price of $215 to come to my home and flash the TCM with the VIN and latest software. DAMN! You were right Hummerz - that is an expensive paperweight I had! Haha :-). I got the programmed part for $80 total from the person you recommended. It hasn't arrived yet but hoping it works. Thanks again for the help.

 

they charge as much as getting a Chinese clone GM MDI programmer. you used to be able to get Chinese tech 2's for around that price a few years ago as well

 

+GM charges a flat $40 to access all the software/programming for a single VIN number.