Weird downshifting

zakkb787

<that’s not me...
Sep 29, 2014
2,340
52
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Granite Falls NC
Please forgive me if there's another thread like this. I searched a bit but never found anything. Anyway if I'm going downhill and hit the brakes around 40-50mph sometimes my trans will downshift and hold back I. Third. And it takes more than the usual speed or throttle to get it out of third. Now if I slip it into neutral and back to drive it goes back to normal. Rpm goes down near idle and just rolls. I don't remember it being like this before it was limped before I built the tranny. But it's getting on my nerves. Is this normal? I didn't do a relearn when I did the trans because honestly I didn't know. Should I pay to have that done now or will it make a difference. I have very specific shift points now too. Don't remember that either... sorry if that's a lot of info and questions
 

Wikid

Machinist and Know things
Oct 21, 2016
88
0
6
Texas
Are you in tow haul mode? when not in tow haul mode mine will just coast unless i put it into a gear. if i am in tow haul mode it will down shift and hold a gear to engine brake.
 

apwcu

Member
Mar 10, 2016
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6
Mine will downshift to 4th sometimes if I'm hard in the brakes when not in tow haul mode.

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IOWA LLY

Yes, its really me
Feb 23, 2007
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Is there any way to get this tuned out Mike?



I'm not Mike. Well gee I guess that's obvious huh? Lol.

But the answer is no. There is absolutely nothing available in Efi live that I have found to alter grade braking shift strategy. Just learn to love it!


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2004LB7

Well-known member
Dec 15, 2010
6,967
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Norcal
I'm not Mike. Well gee I guess that's obvious huh? Lol.

But the answer is no. There is absolutely nothing available in Efi live that I have found to alter grade braking shift strategy. Just learn to love it!


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Raising the MPH down shift at 0% throttle will make it grade brake. Late shift/higher MPH will lessen it. I have my TH mode pretty aggressive and converter locked though out.

On my normal mode, at 0% it is set lower with converter unlocked to allow as much coasting as possible
 

IOWA LLY

Yes, its really me
Feb 23, 2007
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Raising the MPH down shift at 0% throttle will make it grade brake. Late shift/higher MPH will lessen it. I have my TH mode pretty aggressive and converter locked though out.



On my normal mode, at 0% it is set lower with converter unlocked to allow as much coasting as possible



You cannot change the grade braking downshift points. If you think you can your wrong.


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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
You can put a 2001 tcm tune in and get rid of it damn near though. Best option



Yes but you loose over drive lock out. If the op doesn't use it, no biggy.

Personally I'd change up how you are applying the brakes. The truck has a pretty damn good system of judging when to use grade braking. If you are applying the brakes hard and for a certain amount of time (longer than normal), it will kick the grade braking in. There is much more to it than what I stated that is taken into account but try slowing more before the hill to use less brake or change up your length of time on the brake. How many times you apply the brake in a given time period affects it as well

I can almost make my truck grade brake when I want or not grade brake when pulling a trailer down a hill based on brake input.
 

zakkb787

<that’s not me...
Sep 29, 2014
2,340
52
48
Granite Falls NC
Yes but you loose over drive lock out. If the op doesn't use it, no biggy.

Personally I'd change up how you are applying the brakes. The truck has a pretty damn good system of judging when to use grade braking. If you are applying the brakes hard and for a certain amount of time (longer than normal), it will kick the grade braking in. There is much more to it than what I stated that is taken into account but try slowing more before the hill to use less brake or change up your length of time on the brake. How many times you apply the brake in a given time period affects it as well

I can almost make my truck grade brake when I want or not grade brake when pulling a trailer down a hill based on brake input.

Usually mine doesn't grade brake when I get on the brakes heavy. It only does it on slight declines and I'll barely tap the brake pedal to give a little bit of rolling resistance and it'll kick in
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,670
5,817
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Phoenix Az
Usually mine doesn't grade brake when I get on the brakes heavy. It only does it on slight declines and I'll barely tap the brake pedal to give a little bit of rolling resistance and it'll kick in



I'm not saying heavy breaking is the only way it activates. Many different variables can kick it on. I just suggest trying something different than what you are doing now to stop it from happening. You are the easiest variable to change
 

IOWA LLY

Yes, its really me
Feb 23, 2007
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0
Probably am but seems to work on mine. Maybe it just seems like it changes it



You can change when it downshifts at 0% throttle in normal conditions yes. Just can't change the grade braking functions. As James has stated different conditions will trigger the grade braking, and depending on its mood it can be quite aggressive!


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zakkb787

<that’s not me...
Sep 29, 2014
2,340
52
48
Granite Falls NC
You can change when it downshifts at 0% throttle in normal conditions yes. Just can't change the grade braking functions. As James has stated different conditions will trigger the grade braking, and depending on its mood it can be quite aggressive!


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I guess my truck is moody then