Ok I will first start off with when it started to occur.. the transmission and everything was working fine until i took a small road trip. (150 miles). Isn't far at all.. During that road trip while i was on the highway i was going around 45mph and all of a sudden my truck downshifts and then upshifts right after and did a little stumble. ever since then it has been doing it at any speeds. if I'm going say 35mph as soon as i press the pedal just enough to hold a steady speed it will downshift then upshift directly after and jerk the truck a little bit after it shifts. I have no idea what it is. I don't know a lot about transmissions. Maybe someone that had the same problem will help me. Please help lol. I have searched around for weeks and haven't found anything similar to my problem.

 

Have you checked for codes? It sounds like something electrical (that controls the tranny) maybe the TPS? It could be giving false readouts to the transmission, causing it to get confused. May not be the solution, but who knows!

 

I have checked for codes with my matco obd2 scan tool. And no codes come up. thats why im so stumped lol.

 

any of these help?
FYI 4L60E common problems / failures | GM Truck Headquarters

 

I just read that entire page and none of those problems are like mine.. Thats why i say im stumped. Because it seems like noone else has had this problem.

 

Is there a way you could (safely) take a video of what its doing, and then post it here?

Also, are you sure its a downshift, and not just the torque converter unlocking? Have you tried to drive it while manually shifting through the gears? Does the transmission shift smoothly through all 4 gears?

Does your truck have any symptom of a failing fuel pump (whining, hard starts, low power, etc)?

Sorry to bombard you with questions, but theres a lot that could be wrong here!

 

Yes i could post a video of what it does and then post it. And im not exactly sure what it is. maybe you can figure out more from the video. Ill try to record it later and then post it. and i havent tried driving it through all 4 gears manually but ill try it.

 

My first suspect is the tps, I would either ohm test it or drive with a scan tool hooked up and watch the input data

 

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Watch the video I just posted and you will see what it does.. Its rreally crappy quality but you can still see what it does lol.. What happens is when im driving at a steady speed the rpms jump up and down. Anyone plz?