Help: Duramax wont shift?!

junkchevy

New member
Sep 1, 2015
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I have an 03 6.6 duramax. The other day I was driving and when I shifted from reverse to drive my truck hopped into drive pretty bad. I babied and drove the truck about 3 miles away, but it won’t shift out of 2nd gear and hits 4 grand while going 45mph. I shut the truck off for a few minutes and tried leaving again and it jumped really bad from park to drive. I babied it home and let it sit for 2 days and drove it. It drove perfectly fine. The next day it drove fine, but when coasting and downshifting you can hear a grinding/winding like noise. Today on my way to work it wouldn’t shift or go over 45mph without hitting the rev limiter again. All the temperatures are normal, you can’t smell anything burning and the tranny fluid is full. I think it does it when I try to get into the pedal, it will slip from 1st to 2nd and then wont shift from there, but if it’s babied and eased into shifting very slowly it hasn’t happened yet. What could this be?
 

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
Check the main round plug that goes in the Trans. With that unplugged it stays in 3rd I think.

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junkchevy

New member
Sep 1, 2015
3
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0
I changed the filter and fluid like 3 weeks ago, when it started this. We checked all wires and everythings hooked up as well. im stumped
 

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
Make sure that plug isn't full of fluid.

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sschevyfreak

New member
Sep 11, 2015
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Been having a similar problem.stuck in 4th gear , stopped, tried to go still stuck in forth pulled over turned off and on nothing turned off again crawled around underneath, reset my trans on my tuner then turned on shifted a little hard but been running fine since threw code for pressure control valve stuck on.i been hearing that the valves try to go at the same time and bend making it occur more and more


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