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Discussion Starter #1
Hi All,

I have a 2005 gmc crew cab LLY with the 5 speed. I have been noticing that when under moderate acceleration, it shifts funny between 3-4 gear. It begins the shift and during mid-shift it is like it goes into neutral. The revs pick up to about 3k at moderate acceleration, then it shifts into 4th and goes into 5th fine. All other gear shifts are normal. I also noticed it pulling a camper last weekend. The problem seems intermittent, and sometimes it shifts fine. Hard acceleration seems to dampen the effect. I DO have a bum nsbu switch that I have been meaning to replace, Could this be part of the problem? The truck has never gone into limp mode.

I began noticing the shifting problem right after i took it to a gmc dealer to get the trans fluid changed. I will never go there again. They only put in 6 qts of oil at the change, and changed the external filter only. I have read that the typical, non-flush change requires around 10 qts. The oil levels appear to be fine with no burn smell or discoloration, but I wanted to point this out in case anyone had an idea as to what may have changed at the dealer. They put in Dex 6, not sure what was in it before the change.

Thanks in advance!
 

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Discussion Starter #2
Another thing to note, I've heard the trans whining ever since the stealer had it, which suggests low trans fluid, but I've cold and warm checked it several times, both of which look good on the stick..
 

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Discussion Starter #4
c'mon guys, some ideas please. Starting to think just a low fluid level, even though a hot trans fluid level test does read in the hot zone, it is low on the hot zone. Could this be it? I'm doing the hoots on sunday.
 

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I thought I read the 5-speed used Dex 3? If it isn't low, then that's (probably) not the problem, but wrong fluid could be.
 

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I run Transynd in my trans.
 

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Discussion Starter #7
Thanks for the replys. I checked the levels, and like I said it was within the hot zone, but low within the hot zone. I just changed the fluid, didn't do a hoot flush since nobody was available to help, but I changed it ran it awhile, and changed it again. I figure I have about 1.5-2 qts left of the bad dex 6, good enough for me. I used valvoline dex 3, and filled it until it was mid-hot range during a hot test. The truck seems to shift fine now. Time will tell. I also changed my nsbu and cleaned the plug with electrical cleaner and used a lot of di electric grease. I'm hoping all that helps the nsbu last longer.
 
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