LMM Transmission Issues

JDT4430

JDT4430

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Jul 29, 2014
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The other day while sitting with my truck idileing it popped up the Service Stabila Trac. Few minutes later took off to find out that the trans was locked in 3rd or 4th gear. Pulled over shut it down and restarted and it did not help. Got to my dads shut it off for a few minutes then started it back up and drove a 1/4 mile down the road and it did fine until i turned around then it messed up again. When i got home I pulled the codes and they were P0706, P0708, P0729, P0894, cleared them and the truck did good for a couple days then on my way home from work it popped the codes again this time it was P0708 and P0700. Cleared them and it didnt make it 100 yrds and messed up again so i stopped shut it down cleared the codes again and if i remember right it made it home after that. Then the next time the codes were P0708 and P0701, the next time was P0706, P0708, P0894 and P0701 after that was the same.
The codes popped up several times under different driving conditions and sometimes while sitting in gear with my foot on the brake. If any one has any ideas what it could be please let me know.

P0700 Transmission Control System Malfunction

P0701 Transmission Control System Range/Performance

P0706 Transmission Range Sensor Circuit Range/Performance

P0708 Transmission Range Sensor Circuit High Input

P0729 Gear 6 Incorrect Ratio

P0894 Trans Component Slipping

Also a couple of times it gave me the shift inhibited message and would not go into gear.
 
IOWA LLY

IOWA LLY

Yes, its really me
Feb 23, 2007
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TCM would be my first guess.


Sent from my iPhone using Tapatalk Pro
 
JDT4430

JDT4430

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Jul 29, 2014
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Thanks for the fast responce. Will the TCM from my LBZ work in my LMM. If so is there anything special i meed to do after swapping them or is it as easy as swapping them out. Is the TCM the module that is on the fan shroud?
 
Ne-max

Ne-max

I like turtles
Nov 15, 2011
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Lincoln, Ne
JDT4430 said:
Thanks for the fast responce. Will the TCM from my LBZ work in my LMM. If so is there anything special i meed to do after swapping them or is it as easy as swapping them out. Is the TCM the module that is on the fan shroud?
Click to expand...

Lbz is different. Yes it's on the drivers side fan shroud. New one from gm will need programmed
 
JDT4430

JDT4430

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Jul 29, 2014
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Ok thanks. Will one from another LMM be a simple swap or does it have to be programmed to my truck.
 
$

$chultz38

Member
Jan 22, 2009
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Take it off and look at the back of it it will say a40 or a50 then find the one you need. Do you have a efilive v2?
 
JDT4430

JDT4430

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Jul 29, 2014
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Yes i have efi live V2. I have a friend that has an 08 so i will just go pull his and mine and check the numbers. Hopefully they will match and i can either fix the issue or at least elimante one possiablity.

Woild also like to add that so far for the duration of this problem which has been about a week and a half as long as I leave the truck over night with no codes it does not act up at all on my drive to work which is about 45 min drive. But i usually acts up close to the end of my drive home.
 
$

$chultz38

Member
Jan 22, 2009
230
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Just saw that your truck is '09. Not sure yor buddy's TC will help you.
FYI- you can use a LML TCM and flash in your TCM files.
 
Harbin_22

Harbin_22

Active member
Dec 4, 2010
3,858
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38
Southern Indiana
Any LMM TCM can be swapped. My 2010 is using an 07.5. No reprogramming needed. I did do a relearn since I had a built trans and this one came out of a stock truck.
 
JDT4430

JDT4430

Member
Jul 29, 2014
75
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Harbin_22 said:
Any LMM TCM can be swapped. My 2010 is using an 07.5. No reprogramming needed. I did do a relearn since I had a built trans and this one came out of a stock truck.
Click to expand...

Thanks for the info. I think I will give it a try. Talked to my dealer today and the new TCM is $705 plus another $200 for them to flash it and then they said they would drive the truck and set it up. Not real sure what that means amd kind of sounds like bullshit but wjat do you guys think? So really want to try another TCM before paying for something like that. Today it was banging in and out of gear and felt like it was going to just snap something then when i slowed down to turn into a drive way i think ot decided it wanted to go to park and locked the rear tires and brought me to a complete stop then went back into gear so i really need to get this figured out before i really mess something up.

Again I really appreciate all the help and I am glad to be a part of a forum like this.
 
Ne-max

Ne-max

I like turtles
Nov 15, 2011
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Lincoln, Ne
New ones are 275 on Amazon. You might be able to pull current file off your tcm and flash it into new ones.
 
$

$chultz38

Member
Jan 22, 2009
230
5
18
Harbin_22 said:
Any LMM TCM can be swapped. My 2010 is using an 07.5. No reprogramming needed. I did do a relearn since I had a built trans and this one came out of a stock truck.
Click to expand...

Both must have been A50s then?
I think 50s go into 40s but not the other way maybe?
 
Last edited:
rfletes79

rfletes79

Active member
Mar 5, 2010
636
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Galt, Ca 95632
New tcm’s Need a full flash to get the calibration on them. You cannot do that with a flashscan.

I’ve purchased new ones online then drove the truck to the dealer and had them do the install and flash. Was the best deal I could find at the time.
 
Ne-max

Ne-max

I like turtles
Nov 15, 2011
3,361
64
48
Lincoln, Ne
rfletes79 said:
New tcm’s Need a full flash to get the calibration on them. You cannot do that with a flashscan.

I’ve purchased new ones online then drove the truck to the dealer and had them do the install and flash. Was the best deal I could find at the time.
Click to expand...

Not true.
 
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