Hmm TPS sounds like it could be involved, but is that same TPS the ECM looks at for fuel management? I would think I would have more obvious problems if that were the case with the engine running poorly?

Thanks for all the helpful replies so far!

 

not really, yes the ecm uses the tps as well, but the pcm uses the speed sensors, tach, engine temp etc. to select the proper gear and tc lock up. they are one big inter twined ball of spaggetti. the tps has been a long time problem in the daks, even in gen 1. to get the code, turn the ingnition on then off twice, the 3rd time leave it to the on pos. the code will show up in the odometer with a p then the code. example= p0303

 

Code is "p doNE" then flips back to the mileage.

 

i reread this from the begining, when was the last time you did a tune up? it is ringing a bell with me on a prob i had several years ago. my truck would feel like it was "slipping" into the next gear and down shifting way to easy. my tech changed my plugs and solved the problem. i had 45k miles on the plugs, i beleive dodge recommends 25k on the 01 and up 4.7.

 

I changed the plugs not more than 2 years ago. Maybe 30k miles ago. However, at that time I did not know that these engines seem kind of picky with plugs, so I'm not sure if what I used is good or not. I never noticed a difference.

Did you notice issues at most speeds, or gear, or rpm though before you did your tune up? Like I said my problem is strictly in the 40-60mph area. Above that and the clutch is engaging and disengaging fine, just like it always has. Throttle response is also fine.

 

i mainly noticed it at the range your talking about, when the truck needs horse power not torque. 70mph was never a prob cause the rpm's where high enough, at 40-50mph is where mine is deciding to lock the tc or not. mine really was noticeable when i was houling even a little weight, 500lbs.

 

To get a code that is in the tranny you will need to go to the dealer or to someone with a starscan or similar. My thinking it is only in one gear so it's unlikely that it will be speed sensors. You will save a lot of time and money by reading the code.

 

Sorry, my mistake. Just realised that you said in the 1st post that it has been like that since new. Is it getting worse?

 

The problem I am describing just started happening. I'll swing by a dealer and see if there is a code.

 

Just an update on my problem. About a month ago cruising down the highway the truck actually downshifted to like second and gave the engine light (first time). Running the code said TPS problem. Replaced the TPS and everything is back to normal, including the lock up clutch going in an out above 40mph. $36 and problem solved!!! Very happy my tranny appears to be ok. Hope to get another 150k!