to make sure we are stating it correctly the manual calls it 'engine braking'...
so, yes, you win, it's not an 'exhaust brake'...
but it's ford's version of it
I haven't been on the 'hills' you have,
but two scenarios where it downshifts on it's own..
when cruise is set and the speed starts to go more than 3 or 4 mph higher, it downshifts to slow down (even when NOT in tow/haul)
also, without cruise, if tow/haul is on and I hit the brakes, it starts downshifting...
from the manual you can download on
owner.ford.com:
INTEGRATED ENGINE BRAKING
This feature increases engine braking at higher engine speeds to provide better grade descent control with less brake and transmission wear and
tear. This feature is integrated with the tow/haul mode feature.
When tow/haul mode is switched on, the integrated engine braking feature will also be active. For more information on tow/haul, see Automatic transmission operation in the Owner Manual.
D (Overdrive) with Tow/Haul Off
D (Overdrive) with tow/haul off is the normal driving position for the
best fuel economy. The overdrive function allows automatic upshifts and
downshifts through gears one through five.
D (Overdrive) with Tow/Haul On
The tow/haul feature improves transmission operation when towing a
trailer or a heavy load. All transmission gear ranges are available when
using tow/haul.
Warning: Do not use the tow/haul feature when driving in icy
or slippery conditions as the increased
engine braking can cause
the rear wheels to slide and the vehicle to swing around with the
possible loss of vehicle control.
TOW HAUL:
Tow/haul delays upshifts to reduce frequency of transmission shifting.
Tow/haul also provides engine braking in all forward gears when the
transmission is in the D (Overdrive) position; this engine braking will
slow the vehicle and assist the driver in controlling the vehicle when
descending a grade. Depending on driving conditions and load conditions,
the transmission may downshift, slow the vehicle and control the vehicle
speed when descending a hill, without the pedals being pressed.
The amount of downshift braking provided will vary based upon the
amount the pedal is depressed.
Tow/haul may be automatically activated (without pressing the tow/haul
button). This provides engine braking to assist the vehicles braking
system when going downhill and repetitive braking is sensed. Once the
tow/haul mode has been automatically activated it will not automatically
deactivate (didn't know that - I learned something today !)