So, after the fiasco last year and early this spring with the trans, here I am again.... but hopefully it is just a sensor, but I will gladly take opinions.

truck has driven great since the trans was finally fixed, but today, no load on it, the truck shifted from 2nd to third, and started revving up like the tow/haul was kicking on and off. I finished the drive and it happened several times. I took it to my shop, trans fluid is full, doesn't smell burnt, and is a good red color. The only thing I didn't like was that when I cleaned the stick, there was some brown coloring that came off with the fluid. I checked it 3 or 4 times, and the last time there wasn't much that came off.

 

Just went out for a drive to check more details. No slipping of converter, holds solid through all speed variations I tried @ WOT. What I did notice towards the end of the drive, is the gear selector ring around the " D" is flashing off and on. When the truck was acting like it was in tow/haul mode, I turned the mode off/on with the switch and nothing changed. It is now though, acting like it is in tow mode with a large load behind me, keeping high rpm's right off the get go all the way to 60mph, which is where I let off. It does this all of the time now. I did drop it in N at a stop sign, and when I put it back in drive and went across the intersection if felt like it lost all drive power 2 times, just momentarily, and then took off.

 

took the truck to the dealer, they told me all my error codes were voltage spike and low voltage codes. my batteries are at least years old, so I replaced them and polished all the connections. Low and behold, the problem is fixed. test drove the heck out of the truck, and everything is in working order now.

 

turns out I was wrong, truck started acting up again today. Has all of the same symptoms. Replaced alternator because battery gauge was all over the place also. Didn't help. No codes showing on dealers machine. I'm thinking ECM. any thought on that?

 

Mine started like this, stopped after I got off interstate and pulled out sluggish, I thought a brake was dragging. Brakes were cool, unloaded the truck and took it a spin seamed fine. A couple of days later did not **** into 3 correctly, seamed to over rev, let off and it shifted. Took it to the shop and they read a low voltage code, replaced the terminal that were 10 years old. A day or two later same thing. Took it back and the pressures in the transmission were very low, something like 25 psi and should be 60, apparently a seal had developed a leak, not happy but it did have over 200K on it. Transmission re-build and now I have 225 or so on it no other shifting issues.