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I may not be searching the past threads correctly but I haven't found anything regarding this issue.
My 2020 F-350 DRW PSD will automatically downshift while going downhill no matter what. I have the exhaust brake off and in normal diving mode. It's no big deal when the weather is dry, but with slick winter roads and these Ozarks hills, this could quickly become an issue.
Is there anything that I can change in Forscan or anywhere else?
Unless your transmission is downshifting so hard that you think it will lock up the wheels, if that is the case, you have other issues
There is no way for the transmission, not the downshift, imagine you're doing 35, 40 mph in 7th gear....... You take your foot off the pedal. Then you step on the brake, and slow down to 15 mph, You're asking for your truck to stay in 7th gear? Imagine the slam of it going into second or third, the lag, etc
been my experience with heavier trucks and lower gearing that you can feel the transmission downshift as you come to a stop. It is fine and does not cause any issues with ice or anything.
As said if it slams or is hard and abrasive that is different.
Unless your transmission is downshifting so hard that you think it will lock up the wheels, if that is the case, you have other issues
There is no way for the transmission, not the downshift, imagine you're doing 35, 40 mph in 7th gear....... You take your foot off the pedal. Then you step on the brake, and slow down to 15 mph, You're asking for your truck to stay in 7th gear? Imagine the slam of it going into second or third, the lag, etc
I'm maintaining the same speed or even rolling a 5 to 10 mph faster not trying to slow down.
Is the cruise control engaged when this happens? If so that is perfectly normal. Cruise will only allow the vehicle to gain so much speed before it downshifts in order to bring the speed back down to its setting.
If no cruise, sounds like a TCM reset may be helpful.
Find the Yaw sensor in your truck and put a shim under it so your truck thinks you're always going uphill...
In my 2018, it was on the floor under the jump seat/center console
Is the cruise control engaged when this happens? If so that is perfectly normal. Cruise will only allow the vehicle to gain so much speed before it downshifts in order to bring the speed back down to its setting.
If no cruise, sounds like a TCM reset may be helpful.
You are correct that unwanted rear axle braking can cause a loss of control on snow/ice. I have had that experience with my old Cummins with a Banks Brake. The switch on the shifter is supposed to disable the brake when you don't want it, but due to Bank's incompetence, the brake would still trigger if the engine was cold, as part of the warmup programming. After a couple of scary skids, I wired in a master switch so that I could completely disconnect power to the banks brake when I needed to.
My only suggestion is that when you're in sketchy conditions, use manual shift mode and/or bump it into neutral. I'm still learning the ways of this new 10r140, and I haven't been through a winter with it yet. Fingers crossed.
The only odd thing I have noticed is going from third to second the engine accelerates a bit. This only happens when manual shifting and the truck is near level or pointed downhill.