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downhill assist stupid ? of the day

9K views 16 replies 10 participants last post by  pleiad7 
#1 ·
Does my 2006 forester xt limited have a down hill descent assist on it? If so, how do i use it?
 
#6 ·
What is downhill assist?

You have gear positions below D (3rd is particularly useful) that you can use for engine-braking, if that's what you're referring to. It's also outlined in your owners manual.
 
#10 ·
yes, the brake. Downhill assist is for steep grades. You can just activate it and the car moves as slowly as possible using engine braking and continuous abs as far as I know. I guess I'll just put it in first and modulate the brake pedal. I doubt I'll be pushing it this weekend anyway, but I was just curious.
 
#12 ·
No the Forester doesn't have it.

The idea behind the downhill assist control is it has the ability with the ABS pump and wheel speed sensors to individually actuate the brakes at each corner. By being able to actuate them individually it allows the system to alternate which brake is being applied so no one brake is overheated during the decent of a hill. Many people will ride the brakes all the way down.

This video is a good one for being able to hear the ABS pump going to town.


As others have said proper gear selection and engine braking virtually eliminate the need for DAC allowing you to lightly use the brakes as needed.

My humble opinion would be that it is a needless feature, that is not needed providing the driver has been educated on how to handle the situation. However new vehicles already have the required components(ABS system) to make it work it just requires some programing and the ability to turn it on, so why not.
 
#13 ·
My wife's 2004 Highlander has it. At speeds above 50, if you touch the brake pedal for a few seconds, the transmission shifts from 5th to 4th and provides an additional engine braking effect. Otherwise it feels like it's free wheeling when going downhill.

Never having owned an automatic Subaru, I can't speak to this feature on the 4EAT or the 5EAT on the Legacy/Outback.
 
#15 ·
Our Sienna does the same thing and I would not equate it to the kind of downhill assist that some off-road machines have. Its for a different purpose, to add a bit of engine braking on longer hills at highway speeds. The off-road kind, as noted, actually applies the brakes to help control, at low speeds, descents on very steep slopes.

As far as I know, my Forester does not have it, nor is it mentioned in the owners manual. I have gone down long hills and applied the brake and do not get the downshift the Sienna gives. I just make good use of the manual shift mode of the AT to engage a bit more engine braking. I have never in my years of off-road driving ever been in a situation where downhill assist was needed. Nice to have yes but not needed. Driving technique is more important.

Edit: just saw Silke's post and I do not get that downhill control mode noted at the end. Maybe something to follow up on or maybe the current gen 4EAT does not have this?
 
#14 ·
Did some digging and found this info in the Summer 2003 edition of Endwrench... it applies to the Phase II 4EAT on the older (SF generation) Foresters, but I'm assuming the newer 4EATs will have a similar provision.

1999 4EAT Transmission Operation

There are seven different shift schedules/
maps in the TCM logic control of
the 1999 Second Generation 4EAT. They
are Normal, Power, Slope, Hold 2nd,
Cruise, Hot ATF, Cold ATF. The shift
schedule/map will determine how and
when the transmission shifts. For example,
in the slope mode, when driving up
a hill under certain engine load conditions,
the TCM will shift the transmission
back down to 3rd gear.
In most cases, the transmission will
stay in 3rd gear until the vehicle reaches
the top of the hill, then it will upshift.
This is done to keep the transmission
from upshifting/downshifting in and out
of 4th gear needlessly. On the uphill
control, the slope angle is estimated
from the throttle opening angle and
vehicle speed change. When the TCU
detects that the vehicle is moving
uphill, upshifting is restrained by selecting
a special shift map, which prevent
needless upshifting/downshifting.
When driving downhill, under coasting
conditions, if the driver touches the
brake pedal, the TCM will downshift the
transmission into 3rd gear to provide
engine braking. This downhill control is
canceled when the TCU detects the
vehicle acceleration by the driver’s
depressing of the accelerator pedal and
input from the Throttle Position Sensor.

Both of these conditions are part of
the slope control logic and are a characteristic
of the vehicle TCM logic.
 
#16 ·
Im not sure if it does or not ,.. Now i have to go try it out next time I take the car out. I do know it holds 3rd up hills from a stop sign when it could easily shift into 4th, And it doesn't actually shift into 4th then OD (lock up) till your on flat ground..
 
#17 ·
Slope control is also outlined in this tech document: http://www.endwrench.com/pdf/feb2004pdf/4EATPhase2.pdf

Slope Control
This control regulates shifting up from 3rd to 4th
gear when traveling uphill and forcefully downshifts
from the 4th to 3rd gear when traveling downhill.
The TCM determines the driving force of the traveling
vehicle from input of the speed sensor signals,
throttle signal, turbine sensor signal, etc., and forcefully
maintains 3rd gear.
 
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