M1161 Transmission info?

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Rasmusrentals

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Murrieta, CA
When I engage my Transmission into any forward gear it goes to a higher gear, It doesn't start out in first and it doesn't upshift. If I am in high range it boggs so bad I can not really take off, If I put it into 4 low I can drive it but it doesn't shift up or down. Reverse works good, but in forward it seems like it is going into some sort of fail safe mode.
It is not the original trans, I can see that it was changed to according to the witness marks on the bellhousing adapter as well as the front drive shaft was not tightened at both ends and the belly pan was missing half of the bolts.
Does anyone have any info on them recalling and changing the transmissions? or any technical manual with troubleshooting ? The transmission does have a part number tag hanging from it. The Growler only has 67 hours on it and the Quality inspection tag from 2012 was still hanging from the windshield latch, so I don't believe they used it.
There is also some sort of breather mounted on the firewall, passengerside, that has a breather hose going to the trans and the transfer case. It is leaking quit a bit of fluid after I drive it. It appears to have a solenoid on it. Any info on that would be much appreciated.
 

NDT

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You are correct that the General Motors 4L70E transmission is in limp mode due to the brain (TCU) being unpowered, missing, burned up, harness unplugged, ???? Start digging into it.
 

W427

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Seattle, WA area
When I engage my Transmission into any forward gear it goes to a higher gear, It doesn't start out in first and it doesn't upshift...
Yes, the transmission fuse is an easy first check, as are loose or bad connections, and others. There is a generic troubleshooting guide from the company that makes the ITV transmission controller in a post here: 4L70E Hope that helps!
 

Rasmusrentals

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I believe it is the TCU that is at fault, I cannot find a fuse for the transmission, only one for the transmission fan, is there another fuse that I don’t see for it? I have power at some of the pins on the harness that goes to the TCU. I think I am going to buy a stand alone TCU as the cheapest replacement one is $1000.
I would like to try my TCU on another Growler to see if it is bad.
 

NDT

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I disagree. Knowing the USMC and your report of how your trans was only partially installed, sounds like the maintenance shop cannibalized the new transmission out of your truck and put the dead one back.
 

W427

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I suppose you could try it in one of mine at the end of the month. ;) I agree, there are other TCUs you could use, keeping in-mind you'll have to program and tune it. Generally no biggie, but I'm not yet sure of any/all special functions such as rear-steer lockout.
 

Rasmusrentals

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Murrieta, CA
I will drop the pan next to see if there are any signs of debris.
Also my speedo does not work, I changed the trans output speed sensor, the old sensor was leaking fluid. The new sensor did not fix the speedo problem, that is another reason I believe the TCU is dead.I have opened up the dash and the panel between the seats and chased all of the wiring down, it all looks to be in good condition.
 

Rasmusrentals

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From what I see with all of the diagnostics I have done the rear armrest will work with a stand alone unit. In the shift housing there is a micro switch that senses reverse and first gear shift positions and I am assuming that is for the rear steer as it only works in those gears.
 

Rasmusrentals

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Murrieta, CA
From what I see with all of the diagnostics I have done the rear armrest will work with a stand alone unit. In the shift housing there is a micro switch that senses reverse and first gear shift positions and I am assuming that is for the rear steer as it only works in those gears.
I love spell check It changed rear steer to rear armrest lol
 

W427

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Seattle, WA area
In that manual I posted, there's a pin-out you can check for the DTC output wire. You can read the trouble codes on that output that might help with diagnostics. 🤷‍♂️
 

Rasmusrentals

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Murrieta, CA
I called Powertrain Control Solutions (the company who made the TCU for the Growler) to ask about testing and or repair to the Transmission Control Module. The Tech guy I talked to said "that was made for the military, just throw it away, we don't care about anything made for the military. The PC board we put in those are disposable."
"We made a bunch of them and we won't help you with it".
I was pretty pissed off with his attitude toward stuff they make for our Servicemen. I gave him a ration back, asking him if they care if this vehicle fails in battle and 4 Marines die.
Anyway, I researched a few standalone TCU's and I settled on one made by a company local to me in So Cal.
I ordered a "Go-Shift Electronic Transmission Control" part #546-20010 from Jegs.com The list price was $517. with free shipping. They also had a $50 instant rebate. I ordered it on Friday afternoon and was able to pay $45 for next day Saturday FedEx.
I didn't have time today to do the full install, so I just connected it to the trans and 12V and it works. I now have 1st gear. I will finish up the install tomorrow and post a YouTube video on it Sunday afternoon.
 

W427

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46
14
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Location
Seattle, WA area
I called Powertrain Control Solutions ...
Anyway, I researched a few standalone TCU's and I settled on one made by a company local to me in So Cal. ...
Nice. Let us know how it goes. I presume it's programmable? [EDIT - I see now it's FitTech. They know what they're doing, and generally have a good value price point] I'm more than curious what settings you find to duplicate or improve operation. Anyway, I'm looking into a pre-programmed ready-to-run ITV replacement control board to refit our controllers using the original case and connectors, with a lower price. The intel we each gather should get the rest of us a good solution. Rock on!
 

Pacman5

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Can anyone recommend an adapter for the code reader on the TCM? I’ve been looking for the 6 pin adapter but can’t find the right one.
 

candstrans

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brodhead, wi
I believe it is the TCU that is at fault, I cannot find a fuse for the transmission, only one for the transmission fan, is there another fuse that I don’t see for it? I have power at some of the pins on the harness that goes to the TCU. I think I am going to buy a stand alone TCU as the cheapest replacement one is $1000.
I would like to try my TCU on another Growler to see if it is bad.
number 15 fuse for the trans
 

Rasmusrentals

New member
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14
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Location
Murrieta, CA
Here is the video I posted on YouTube yesterday on installing the FiTech Transmission Controller.
The Fi-Tech engineer was not accurate in telling me that it would work for the 4L70E, it in fact cannot work for it as it has a different type of control valve unit. I returned the Fi-Tech and purchased an EZ-TCU controller. That one is working. Here is a link to my new video about the transmission controllers.

 
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