ok so my 08 gmc 2500 has a confused 6 speed in it. while driving down the highway at 65 it will keep downshifting until rpms hit about 4,000 then will just hang there until i give it more gas and will then shift. it will do this randomly. almost seems like it is in tow haul but its not. in tow haul forget it, transmission has no idea what its doing. shifts up and down so fast you can hardly take off.

 

Do you have a service light?

Last time the air filter was changed? Ever cleaned the MAF sensor?

 

thats the weird thing, no codes, just changed the air filter 2500 miles ago when i changed the oil and fuel filter and cleaned the mass air flow sensor. has done thing for over a year now.

 

Was the maf meter unplugged when you cleaned it?

How long has it been shifting this way?

 

There is a reflash and relearn for shift busyness for the 6l90.

 

awesome thank you


and its been shifting like this for a long time, well over a year.