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Discussion Starter · #1 ·
I have a 07.5 LMM. 1223 Miles

Yesterday I started, backed out, and when I put the truck in drive the truck slipped out of gear (shifter didn’t move) and I got a Transmission warning on the DIC. It said something to the effect of, shift the N to reset. I did this and then shifted back to D. The truck moved about 40 feet and slipped again. This time I got an ABS, Brake and Check Engine lights. I restarted the truck and backed it back into the driveway. I parked then placed the gear selector into M and it showed 4 as the gear selected. I had the DIC set to Trans Temp and it showed 45 degrees.

I placed a call to the OnStar for a remote diagnostic check. The tech replied that the Transmission was not communicating with the ECM and the truck therefore disabled the ABS generating the ABS and Brake lights. The tech said not to drive (duh) and connected me with the roadside assistance. The tow to the dealer was uneventful until the Service manager stated that they would not look at the truck until Monday. I raised the question of transportation.... The Manager gave me a new 08 to drive until I get mine fixed.

Guess I could have posted this in the Transmission section but I think this is an overall truck issue not exclusive transmission issue.

Ok guys what'cha think?

Chris
 

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What do I think? I think you did the right thing by not pushing it, and having it towed to the dealer.

The startup issue could have been something to do with low voltage. Did the truck start any differently?
 

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Need For Speed
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I have an 08 2500 and since I bought my truck in August 07 I have had my dash say shift to neutral to reset twice. Both times I was stuck in snow and was rocking the truck back and forth. I think it is just a safety thing. I just shift to neutral and its fine. But it kind of scares me that you have something more serious because I just put the Banks six gun on my truck and I bet those trannys arn't cheap. Hopefully nothing ever happens. You probibily got one in three hundred thousand that have problems.
 

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Discussion Starter · #4 ·
I have been around the GMT all my life. My mother and uncle both work for GM at plant 6 in Pontiac, building the GM and Chevy tucks.

Towed it gets great millage...... :(

It was the first start of the day, air temp was in the 40s and the glow heater was on for 4 sec or less, cranked up just fine. I waited untill I had a drop in oil pressure and temps climbing on the tranny before I started moving. Overall I am not to upset over a malfunction, but the DIC warning of "Shift Inhibited Select N to Rest" and the truck slipping out of gear bothers me. Could it be a faulty sensor detecting no output shaft speed? Either way, I will hold the manufacture to fix it.

Otherwise I love GM trucks.

Anyone else seen similar problems?

Chris
 

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is here and there.
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have had no issues thus far. about to turn 3k miles.
 

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No Issues with mine so far, can't complain 2000 miles!

2007 Silverado 2500 HD LT Ext Cab SB/Black Ext/Ebony Int/ LMM Diesel
 

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Discussion Starter · #10 ·
I'll fix the sig.... It is a 07.5


I picked it up today, the output shaft speed sensor on the transmission failed (open circut). So when the truck started to move and no signal was found the transmission would slip out of gear and the DIC would desplay the "Shift Inhibited" code.

Dealer had it fixed good to go.

Thanks all

Chris
 
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