Ihave a 99 ram 1500 360 4x4 auto trans not shifting properly between 1st and2nd on light and medium acceleration it changes up and down untill it gets enough speed up to stay in 2nd rpms to high to go back to 1st, if u accelerate hard it is fine it's not the trans i had anotherone installed and it's still the same i also tried a tp sensor still sameno codes.i'mnot sure if the pcm (computer) controls shifts on this vehicle of not. shifts ok in all other gears new tires all same size.anyway i'm open to any advice.

Thanks

 

Maybe the transmission throttle linkage. Do a search on "tranny shift points".

 

My '99 4x4 just started doing this as well. But it's not all the time and usually only goes to 2nd, 1st, then back to 2nd. Or at least that's what it feels like. I think it's because my truck is misfiring though. My plugs are constantly fouling since I've yet tofix the plenum gasket.

I'm hoping it's not a tranny problem. Maybe your truck is missing a little too. Try putting new plugs in and see if it does it.

 

Also adjust the TV cable. I didn't have an issue exactly like what you are describing but I'd still check it. I would have guessed it was the anchor between the first gear band and band adjuster had fallen out as when mine did this I found it laying in the pan when I pulled it to do a fluid change. This caused similar things to what you are describing but since you had a new transmission put in I don't guess this would be the cause unless the one you had put in was bad.

 

It could also be that your tq converter isn't stalling where it used to because of clutch wear or that your motor is not putting out what it used to. If you run right at the stall rpm, or more to the point a certain tq output, the converter will lock and unlock with a light touch of the pedal.