[alberta minimax]

I discovered while towing my boat into a remote mountainous inlet that the power is drastically reduced in low range.
This to the point that I could barely pull up hills.
No wheel spin, traction control or anything else, simply no power.
Power is fine in high range just reduced in low.
I have a pre-EPA GDE tune in my truck.
Cant remember if this was a problem before the tune.
Anyone else notice this either stock or tuned?
Transmission temp was hot, but should have been below de-fuelling point.
Perhaps trans temp de-fuelling happens at lower temp in low range?
Thoughts?

 

[Kunklerr11]

What altitude? Engines de rate at given altitudes.

 

[alberta minimax]

Only a few hundred feet ASL, if that.
Maybe trans temp derailed, but only 100 C.
Shouldn't derate until 115 C.
Will talk to dealer service guy and trans guy.
Just removed my aux trans cooler due to failed fitting at trans from poor support.
Never noticed low power in low range before, but never pulled under those conditions either.
Wouldn’t even spin tires on loose gravel in low range.