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Discussion Starter #1 (Edited)
when my transmission shifts it like it hits Nuetrual for a split second. . .Fluid is full and clean nice red color to it. . .

at wide open throttle it'll shift at 3,750Rpm smooth and solid no issues, but anything in between it Revs up starts to shift jumps 300 rpm then hits next gear.

almost like it slipped ?

I'll do be adding a larger cooler to it soon i will also be doing a fluid n filter change as this time, then another filter change shortly after the cooler swap as its used. . .

Mike
 

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Scan for codes. You may have a bad VSS. It will not set the check engine light. Mine didn't
 

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Discussion Starter #3
VSS ? . . .

I have noticed it dose on the shift from D 3rd gear into OD 4th gear. . .

Mike
 

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Discussion Starter #4
So whats this VSS your talking about ?

Mike
 

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Sounds like a torque converter issue, like its locking and unlocking harshly between shifts.
 

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Discussion Starter #6
I noticed it mostly when i manually shift from d 3rd in OD 4th after climbing a hill. . .
torque converter lock up that sounds like it !

likes its locked in 3rd but then unlocks as it shift in to 4th then locks right back up. . .

ill be getting on the interstate so i'll flipp it back into OD 4th gear then it dose it once it gets to the 3 to 4 shift. . . the trans don't shift when i move the lever it shifts a while after ward. . .


Mike
 

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Vehichle speed sensor. It's on the transfer case. Scan for codes and it will tell you if it's bad. I just replaced mine.
 

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Trans will "usually" throw a code if there is a problem. I would start by scanning it.
 

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Discussion Starter #9 (Edited)
How do i go about scanning it ?

Mike
 

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If the rear output sensor(VSS) or its connection went bad, you would never get out of 1st gear. Good sensor shows around 1350 ohms both directions.I just had a late/hard shift issue because of a so-so connection. Probably not your issue at all if you are feeling it hesitate between gears. How long since a filter check/replace?
 

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Discussion Starter #11 (Edited)
filter replace was last done 15K ish ago according to the paper work. . .

Fluid is full and nice n bright colored. . .

Its not really a hesitation when shifting from D in to OD the tach jumps up 300Rpm as it shifts. . .Giving the visual appearence that it slipped into OD instead of shifting, but i have noticed it only dose it when i manual shift it from 3rd D into 4th OD.
When going up the on ramp to the interstate ( i don't use OD in town i get better mileage) But when it is left in OD/4th gear then it will hit all 4 gears just fine. . .

Tho i don't really hear the engine speed change so maybe another case of twitchy GM gauge ?

Mike
 

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well, if you plan on keeping and working on the truck I think the best investment you can make is GMTDScan.
Mods hopefully this link os OK. I don't think anyone one here sells anything like it.
www.enghmotors.com
I have it. it works awesome. It will tell you what every sensor in the tranny is doing. You will need a laptop .
 

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Discussion Starter #13
Nice tool, now i'll need a laptop those are what $1,000 or so. . .
would a trans shop scan it for me ? for less LOL

Mike
 

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Discussion Starter #14
With new larger cool installed pan dropped fresh fluid added still did it...

Trans shop gave it a scan found no codes ...

I went a on test ride showed him what its dose he said I'm causing the fluctuation by manual shifting from 3rd D to 4th OD ...

Mike
 

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My 3500hd kinda did the same thing and sumtimes if i would lift off the thorttle and get back on it i would go into neutrel and then go back into gear. My cusion works at a gm dealer and i dropped the truck off found out i was a 1st and 2nd solenoid. I bought both 1st and 2nd gear solenoid and 2nd and 3rd gear solenoid also total of 30.00. Fixed the tranny. I would try that there really easy to chagne the on the side of the valve body. Just drop the pan and its right there.
 

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Discussion Starter #16
Yea i may have to do that is now in the last few days it's started doing it on its own i have just left in OD 4th, and now it'll sorta slip shift on it's own into 4th gear over drive. . .

mike
 
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