RPM jumping up and down in overdrive

[topdeadcenter]

I have a 2001 Dodge 1500 (5.2L) with 44,000 miles. Once i reach around 45 mph and am in overdrive the RPM wil jump up 200 and then go back down and repeatedly does this, it does it more when i go over bumps in the road. I turned the overdrive off and ran it up to around 50 to 55 it dosen't do it. Any thoughts on this is much apprecitated

[LTJGWorth]

Sounds to me like it's switching between 3rd gear and overdrive. My truck will switch into overdrive at about 45 MPH, but it's not exactly a good speed to be running in OD, unless you are going at a constant 45 (no slowing down or going over hills). That would probably explain why when you turn your OD off, the RPMs don't jump, because it's not switching between OD and 3rd gear. Of course, there is probably something wrong with it, because it shouldn't be bouncing that much. I'd have it checked out. Try running your truck in OD at between 55 and 65 and report back on what happens.

[fredjacksonsan]

It may also be coming in and out of lockup. In 4th, it's normally locked up but if needs a little more power, will come out of lockup under light or steady acceleration prior to shifting to 3rd. You might want to keep it in 3rd until passing the 50mph mark; interested to hear about the road test suggested previously.

[scoutinkeith]

sounds like your TPS is going bad. my truck did the same thing, wile driving on flat ground, the RPM would just jump and then come back down. at first I thought it was the trans slipping, but it turned out to be the TPS. TPS = Throttle Position Sensor, it's located on the driver side of the throttle body. it sends a signal to the computer that tells it how much throttle you are giving. when the TPS starts to wear out, the signal voltage will fluctuate, and that fluctuation in voltage makes the computer think that you are either giving more gas or letting off(depending on weather the signal voltage spikes or drops off) and when the computer thinks you are either getting on or letting off the gass, it unlocks the torque convertor.
here is a link to some information on how to test the TPS to see if it is bad.
http://dodgeram.org/tech/transmissio...TPS_adjust.htm

[LTJGWorth]

TPS is a big possibility. But normally, if it's the TPS the truck won't idle. It will just quit. My TPS went out in my truck and I had to keep one foot on the gas and the other on the brake to drive it.

[krameryo]

this happend to me didnt think much of it at the time just thought the transmission was pulsating between gears for over the next year it just got worse then started in other gears then lost all forward gears long trip home in reverse drive it till it junks then replace it