I have an '09 Pathy I have owned since new which has been great. I have towed all sorts of trailers with it, and just started towing a large camper that is right at its limit. On the interstate, at 65 mph, it often hunts for a gear on a very minor incline. A headwind really freaks it out. It can shift back and forth several times a minute.

But I'm not really sure what gear I'm in while it is doing this. I turn off overdrive with the stick button, so it says it is in "4". When it shifts down as I described, it goes up about 500 RPM. If I manually move the stick into "3", it goes up about 1000 RPM, so that's a lower gear than what it is shifting into automatically.

Is it not really shifting gears, but just locking and unlocking the torque converter? I don't like stressing that mechanism out, whatever it is.

Is there anything I can do to prevent this? When I control the gas manually, not with cruise control, it helps. Cruise is a bit too aggressive.

Thanks for any information or suggestions.

Chances are it's just locking and unlocking, but your fundamental issue is that the trailer is just too heavy for the truck to pull comfortably. It's expressing its discomfort by constantly shifting to maintain the powerband against the extreme load.

The truck is perfectly comfortable pulling the trailer. At highway speeds I have it far less than 1/2 throttle, usually closer to 1/3. I calculate the average power output to be about 90hp. That's certainly not straining the engine. It just has weird gear ratio spacing, and an over-bias to constantly wanting to shift up.

The RPM jump from 4th to 3rd gear is almost double. That ratio should be closer, IMO. It appears to be unlocking the TC as a poor man's extra gear, like 3rd-and-a-half. I think the transmission is much more stressed out turning the TC on and off, wearing that clutch or mechanism, as well as running it with the TC unlocked, creating extra heat.

I was hoping there might be a way to reprogram the transmission shift points and TC lockout parameters.

It may all be a moot point because last night, towing the camper on the interstate, I hit a deer, and it looks like the truck is totaled. Damn! I liked this truck.

Terribly unfortunate, but it appears that everyone got out of this o.k.?

All the best and future safe travels.

Thanks for asking. Yes, everyone is OK. It was a obviously a bummer to total my truck, and a bit scary, but the main lesson was how lucky/blessed we were, because it could have been really bad. Airbags deployed on the interstate in traffic at 65mph, and I'm flying blind trying to pull over while the trailer is trying to pass us. When the airbag smoke cleared and we saw were were stopped, we happened to be off on a wide shoulder.