4x4 Low Descending Down Hill Issues

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Jesse K Potter

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2019 Ram 1500 Classic Big Horn 4x4 5.7L 8speed 3.21 gearing
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I regularly go down a mile long steep hill that requires 4x4 low and in 1st gear to descend to avoid burning up the brakes. The trucks gearing and compression should slow it down enough, but I find myself tapping the brakes more than my previous truck, a 2006 Tacoma. The truck feels like it holds, and then releases and speeds up, which then requires me to hit the brakes. Wondering if this is the MDS kicking in when descending down the hill because I am not applying any throttle. The trucks engine braking feels sufficient for a moment, but then it is like it gives way and starts coasting.

I am looking into shutting off the MDS to see if it makes a difference when going down a really steep mile long hill in 4x4 Low in 1st gear, no throttle applied.

Do any of you have a similar experience?

I am considering buying an Edge Pulsar to fix this you think by turning off the MDS.

Any thoughts would be appreciated.
 

Travelin Ram

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Can’t help with anything Ram specific as I’ve been stuck in flatlands since acquiring this truck. But I did have the same experience you describe with my previous truck (Chevy) in the same conditions. That truck had cylinder deactivation as well. I’ve been driving off road my whole life and never experienced anything like that until having a truck with cylinder deactivation so you may be on to something.

I’m curious to see what other responses you get.
 

crash68

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Are you using the ERS buttons to keep the transmission in first gear? I thought I remember reading that using the ERS buttons disables the MDS.
 

Jimmy07

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^Yeah, if you’re limiting the gear to 1st, MDS it’s kicking in anyway. If you do stuff like that a lot, you could get the lower switch bank that has the hill descent control button, and enable the feature with AlfaOBD.
 

crash68

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^Yeah, if you’re limiting the gear to 1st, MDS it’s kicking in anyway. If you do stuff like that a lot, you could get the lower switch bank that has the hill descent control button, and enable the feature with AlfaOBD.
Does the Hill Resent Control work on the 1500s or is that for the 2500s? I thought that was a Power Wagon specific option.
 

crazykid1994

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If you lock it into cruise control it should hold rpm and gear to keep you from accelerating to a point. Not sure how well since I’m in Florida and the most I’ve done is north Florida hills. I know it’ll kick down a gear or 2 and the rpms go up and you feel it engine braking. That’s in my 2017 ram 1500 with the 8 speed
 

crash68

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Put the trans in M1 where it should be.
There is no M1 on the 8spd gear selector, just: P, R, N, D To limit the trans to first you use the ERS Gear +/- buttons
 

indept

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If you lock it into cruise control it should hold rpm and gear to keep you from accelerating to a point. Not sure how well since I’m in Florida and the most I’ve done is north Florida hills. I know it’ll kick down a gear or 2 and the rpms go up and you feel it engine braking. That’s in my 2017 ram 1500 with the 8 speed
Cruise control won't engage until about 25 mph.
I know that when coasting at low speed the engine shuts all 8 injectors off to save fuel.
 

crazykid1994

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Didn’t realize you were going that slow. Apologies. With the 8 speed if you select the gear down to first or second it won’t engage mds. The pulsar doesn’t truly disable mds either. I’m not sure what gears the trans locks the tc either because you’ll push through the tc downhill if it doesn’t lock and lose engine braking power as well
 

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There is no M1 on the 8spd gear selector, just: P, R, N, D To limit the trans to first you use the ERS Gear +/- buttons
So you guys can't hold a gear in the RAM with the 8 speed ?
I have a 14 Dodge Durango with the 8 speed trans, but that one has paddle shifters and i can hold any gear i want with those. I would have thought there was something similar in the RAM but without the paddles. With the 6 speed in the RAM i have to press the - button on the column shifter to select the gear i want to hold, M1,M2 etc..
Never mind, i see per you post there is also -+, so what's the problem then ?, can he just select - then go to M1 and hold it there ?
 

manogmin

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I know this is a sucky work around, but supposedly tow/haul disabled mds as well. Have you tried putting it in tow mode and limiting it to 1st gear?


Sent from my iPhone using Tapatalk
 

crash68

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So you guys can't hold a gear in the RAM with the 8 speed ?
I have a 14 Dodge Durango with the 8 speed trans, but that one has paddle shifters and i can hold any gear i want with those. I would have thought there was something similar in the RAM but without the paddles. With the 6 speed in the RAM i have to press the - button on the column shifter to select the gear i want to hold, M1,M2 etc..
Never mind, i see per you post there is also -+, so what's the problem then ?, can he just select - then go to M1 and hold it there ?
With the Ram 8spd transmission you can only limit what it will shift up to, the ERS buttons don't force up shifts. There is no manual mode for the transmission.
There are tuners out there that can make it possible to force up/down shifts
 

Jimmy07

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Does the Hill Resent Control work on the 1500s or is that for the 2500s? I thought that was a Power Wagon specific option.
Ah, yeah. I completely missed his VERY FIRST sentence, and didn’t even think about that. I doubt it would.
 
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Jesse K Potter

Jesse K Potter

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I lock it in 1st gear every time via the Gear Selector on the steering wheel. What I described occurs while in 4x4 Low while being locked in 1st gear.

My truck doesn't have the Hill Descent Control.

Jimmy07: I read the somewhere the computer would have to be changed to get Hill Descent Control installed on a Ram that didn't come with it stock. Are you referring to something else? Or do you know if it is possible without changing the computer?

Travelin Ram: Yeah, same here. Other newer rental trucks I've driven on this same road that has MDS did the same thing, like Chevys like you said. Considering buying the Edge Pulsar to disable the MDS.
 
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Jesse K Potter

Jesse K Potter

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I know this is a sucky work around, but supposedly tow/haul disabled mds as well. Have you tried putting it in tow mode and limiting it to 1st gear?


Sent from my iPhone using Tapatalk


Will try that. Figure it wouldn't work while in 4x4 Low. Anyone know if Tow Haul works in 4x4 Low?
 

Travelin Ram

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Hill descent control systems just automate the use of the ABS / stability control pump to brake the vehicle downhill. That won’t save your brakes on a long descent which is what the OP is trying to do by using compression braking.
 

chri5k

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The only logical solution is a 2500 with the CTD. :D Full exhaust brake will keep her going slow on the descent.
 
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Jesse K Potter

Jesse K Potter

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The only logical solution is a 2500 with the CTD. :D Full exhaust brake will keep her going slow on the descent.

ugh, yeah. That would be perfect of course. Found a really good deal on this 1500 with 7,000 miles as a former Enterprise truck for about $15k less than MSRP, and much cheaper than a new Tundra (which has good downhill engine braking).
We drive 126 miles round trip, so wasn’t looking for gas bill to go up.
 
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