My durango downshifts when driving at highway speed

Can you be more specific does it happen only on the highway what is the speed is it when accelerating does it happen on other roads, does it start right up after stalling as it seems unlikely that it would just be the highway in order to even try and figure it out more information is required

You are experiencing first stages of trans failure, and the 4l60 has a few

First off there may be nothing wrong. At highway speed, the trans will shift down to 1st, but you won't feel it. If should feel like neutral. Does it shift normally when your "wide open throttle" from standstill? If it shifts properly in this situation, then your fine, don't worry. How about wide open throttle at say 25mph? how about 35 and 45? anything over that and its gonna feel like neutral. IF your convinced that your passing gear is not working right, it could mean that its out of adjustment, and needs a little more push, more throw, or kinda like adjusting the rod out a little bit further. Adjust your "passing gear linkage" or kickdown as you imply. Second guess would be low on transmisison fluid, filter, and last, the transmissoin control selonoid. Again I suggest its doing just fine, if it shifts down at any speed.

I had exactly the same problem. It would randomly downshift without warning even at highway speeds. Very Scary!!

After the independent garage couldn't figure it out I took it to the Chrysler dealer. First time through, they did a few things that I knew wouldn't fix it. Two days later I took it back after another scary downshift on the Interstate. They kept it two days.

Believe it or not, the problem turned out to be the ignition switch!!

That was over two years ago, and the problem has NOT re-occured, so they nailed it - and I'm grateful.

shift sensor in trans bad take the tarns apart . well drop pan n fluid the drop out the valve body then u can see the shift sensor

try cleaning or replacing the EGR valve? hope this helps

PCM going bad. real common

check the shift cable, it may have broke or is way out of adjustment. the cable for downshifting. if the cable is ok, then check throttle position sensor at throttle plate on side of throttle body. this has a major effect on transmission shifting.

I have a 2000, there is a speed sensor located in top of the rear axel and I believe another on the tranny housing. Try the rear axel first.

try changing your fuel filter