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Allison 6 speed issues.

T

Timothy_james07

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2007 classic gmc sierra duramax. Truck has reverse as normal. As soon as it’s shifted into drive it goes into shift range inhibited. I’ve tried a different tcm. Replaced the internal harness due to leaking into the plug. Gone through the entire harness. The truck will move forward if the harness is unplugged at the transmission. So far what I’ve noticed is that the turbine sensor won’t go to zero when put in drive. It stays at engine rpm so it won’t allow it to complete the shift. It’s not throwing any codes. Hoping someone that knows these transmission can offer some insight. Starting to think whatever in the valve body that applies pressure to the c1/c2 clutch packs is to blame. Thanks in advance.
 
Thank You Timothy for coming to thetruckstop.us
I know not one thing about transmission problems but its possible there might be someone in here that does.
There is one member of the forum that has been going through a lot of health problems and He is mighty sharp on transmission problems so maybe by using the @ sign I can call Him up and see if he is doing good enough to respond.
@THEFERMANATOR
YOU doing okay ?
 
I just got the same thing yesterday on my 2006 Duramax. A little over 200k on the meter. I drove truck to do some tree work. used the truck all day. I shifted into 4L and gently pulled a tree down. Put truck in reverse and backed up to where I started. Finished up my job, loaded up the truck and started to drive away. Drove about 2 to 3 miles an hour, put truck in N, pushed button from 4L into 4H, Tcase then showed N. I put truck into D and nothing, Allison does nothing when you shift from P to R to N to D. Whole truck stays in N. I get shift range inhibited on DIC.
1ST Time I ever had to get truck towed home...
What gives here? Where should I start?
 
Yes. I tried everything I could. I was cutting wood, so I had no tools. Had to get flat bedded home. The Transfer case seems stuck in neutral, and the Allison when going from Park to Reverse to Neutral to Drive does not respond. Seems like the Allison is stuck in neutral too. The DIC displays SHIFT RANGE INHIBITED...
 
RI Chevy Silveradoman said:
Yes. I tried everything I could. I was cutting wood, so I had no tools. Had to get flat bedded home. The Transfer case seems stuck in neutral, and the Allison when going from Park to Reverse to Neutral to Drive does not respond. Seems like the Allison is stuck in neutral too. The DIC displays SHIFT RANGE INHIBITED...
Click to expand...

Let us know what the outcome is, just in case my 2006 Chevy 2500HD ever does the same thing.
 
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