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Old 03-19-2016, 10:44 PM   #1
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Driving down mountains

What is the proper way to drive a Chevy 2300 Sunseeker/Forester with six speed auto down steep grades?


Use manual and limit gears used or use drive and the cruise control? But as soon as you touch the brakes the speed control is shut off?

Thanks in advance for your help.
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Old 03-19-2016, 11:08 PM   #2
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When driving heavy vehicles up and down hills, you want to go down in the same gear you would go up.
And do your slowing down at the top before starting down a steep hill to reduce gaining too much speed.
If braking, let the brakes cool by braking down about 10 mph and release, when speed increases by 10 mph,
repeating braking down 10 mph. Don't use cruise control.
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Old 03-19-2016, 11:35 PM   #3
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My question is directly related to down hill with Chevy six speed.
Your answer is just a generic answer, and is not directly related to using the Chevy six speed offerings and information on using drive or the manual setting.
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Old 03-20-2016, 12:32 AM   #4
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Driving down mountains

the the advice given was solid. so add the word Chevy in each sentence. use the "m" setting to choose the gear you need. or if in tow haul mode "d" will provide some engine braking, but given it can't tell exactly which hill you are driving down, it is better in manual shift. give the owners manual a read.
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Old 03-20-2016, 08:06 AM   #5
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tow / haul mode = engine braking !
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Old 03-20-2016, 11:32 AM   #6
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Quote:
Originally Posted by poorbuthappy View Post
the the advice given was solid. so add the word Chevy in each sentence. use the "m" setting to choose the gear you need. or if in tow haul mode "d" will provide some engine braking, but given it can't tell exactly which hill you are driving down, it is better in manual shift. give the owners manual a read.
I have not used the M setting yet in my travels but my understanding is that it will not go higher than the highest gear you set it to. That should help with a mountain decent.

I do use the tow/haul option quite often on the steep hills in my area and it definetly helps.
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Old 03-20-2016, 03:22 PM   #7
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Originally Posted by Delco Bobby View Post
I have not used the M setting yet in my travels but my understanding is that it will not go higher than the highest gear you set it to. That should help with a mountain decent.

I do use the tow/haul option quite often on the steep hills in my area and it definetly helps.
Thank you Delco bobby for your input. I have read the Chevy manual and just wanted to touch base on the newer six speed trans and the options given for downhill driving.
This is what I feel the owner’s manual is saying and just wanted to verify that I am understanding it correctly:


For more or less straight down hills were speeds can be controlled by the “Normal Mode Grade Braking”. Which would mean using regular drive selection with cruise control set to speed wished. And with the Tow/haul selection made to add to the effect if needed. I believe the normal mode grade braking is dependent on the cruise being set to the speed desired.


For steeper grades were slowing down for road conditions is mandatory it would be best to use “Manual Mode” to select the highest gear that can be used on the fly and without the cruise control. And this would not give you the automatic grade braking as above. Tow/haul could be used to increase the effect if needed.


I thought it was a simple question and I realize the importance of reading the manual. But I cannot say I never made a mistake in reading some instructions and thought better to check out the details on the Chevy six speed before testing on a steep downgrade. That is why I emphasized Chevy six speed and clearly stating using regular drive verses manual mode. Wanted trans information as this trans offers different options.
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Old 03-20-2016, 05:50 PM   #8
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Quote:
Originally Posted by 17Racer View Post
Thank you Delco bobby for your input. I have read the Chevy manual and just wanted to touch base on the newer six speed trans and the options given for downhill driving.
This is what I feel the owner’s manual is saying and just wanted to verify that I am understanding it correctly:


For more or less straight down hills were speeds can be controlled by the “Normal Mode Grade Braking”. Which would mean using regular drive selection with cruise control set to speed wished. And with the Tow/haul selection made to add to the effect if needed. I believe the normal mode grade braking is dependent on the cruise being set to the speed desired.


For steeper grades were slowing down for road conditions is mandatory it would be best to use “Manual Mode” to select the highest gear that can be used on the fly and without the cruise control. And this would not give you the automatic grade braking as above. Tow/haul could be used to increase the effect if needed.


I thought it was a simple question and I realize the importance of reading the manual. But I cannot say I never made a mistake in reading some instructions and thought better to check out the details on the Chevy six speed before testing on a steep downgrade. That is why I emphasized Chevy six speed and clearly stating using regular drive verses manual mode. Wanted trans information as this trans offers different options.
I just read the manual on this again. It could be made clearer.

I have the 6 speed trans on my 2013 2250 Sunseeker on a 2012 Chevy 4500 Express Van chassis.

It seems to me that the "range selection mode" offers the option to limit the highest gear used. From the manual, "The Range Selection Mode helps control the
vehicle's transmission and vehicle speed while driving down hill or towing a trailer by letting you select a desired range of gears." (Excuse the formatting)

The manual does recommend using the tow/haul mode for downhill driving. I believe this is also referred to as "grade braking." If I understand this correctly, grade braking is not available if the range selection mode is activated.

I believe that the "manual mode" discussed is referring to the 4 speed transmission.

Personally, I would deactivate cruise control on steep downhill sections. I don't think we have an interactive cruise control as some of my recent cars have had. Your vehicle is newer and that may have been added.

I also don't like cruise control on some uphill legs because when the trans downshifts my speed may increase as much as 5mph before I cancel it. this happened on a recent trip on Interstates. I had to cancel the cruise control or ram the vehicle in front of me. My cruise control was set for 65 but I hit 70 before cancelling.

Anyway, I hope this reply makes sense.

Bobby
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Old 03-20-2016, 10:13 PM   #9
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Bobby,
Thanks again for your input. I agree with just about everything you stated. Especially about the manual not being the clearest.


I have used the grade braking feature but only on slight downgrades. It does require you to be in Drive and with the cruise on. But if you need to touch the brakes the cruise shuts off which seems to deactivate grade braking and also allows the trans to up shift. That combination of results is just what you don’t want and is very disliked by me.


I am going to use the range selection mode more often now to get use to the different uses it offers. You do give up the auto grade braking option but it does offer more manual control. Before I get some really steep twisty roads I want to be more aware and comfortable with it.


And it does seem that tow/haul might program the trans for better results.


The cruise control is not the greatest in many ways. It does seem to jump just as you say and can’t be shut off quick enough on up hills. And also when going slower than 10 mph under your set speed and touching resume. Trans jumps down 2 gears in attempt to get back up to speed when all I wanted was just too smoothly increase the speed. I wish it had some type of adjustment for the rate of speed increase. But for most interstate driving it is a plus. Again thanks for understanding my question and replying. Just needed a wall to bounce it off of.
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Old 03-21-2016, 11:19 AM   #10
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Quote:
Originally Posted by 17Racer View Post
Bobby,
Thanks again for your input. I agree with just about everything you stated. Especially about the manual not being the clearest.


I have used the grade braking feature but only on slight downgrades. It does require you to be in Drive and with the cruise on. But if you need to touch the brakes the cruise shuts off which seems to deactivate grade braking and also allows the trans to up shift. That combination of results is just what you don’t want and is very disliked by me.


I am going to use the range selection mode more often now to get use to the different uses it offers. You do give up the auto grade braking option but it does offer more manual control. Before I get some really steep twisty roads I want to be more aware and comfortable with it.


And it does seem that tow/haul might program the trans for better results.


The cruise control is not the greatest in many ways. It does seem to jump just as you say and can’t be shut off quick enough on up hills. And also when going slower than 10 mph under your set speed and touching resume. Trans jumps down 2 gears in attempt to get back up to speed when all I wanted was just too smoothly increase the speed. I wish it had some type of adjustment for the rate of speed increase. But for most interstate driving it is a plus. Again thanks for understanding my question and replying. Just needed a wall to bounce it off of.
First I want to say that I am glad that you brought this subject up on this forum. I had read that section of the manual many times and did not fully digest it. So you gave me a reason to review it again and now I believe I understand what Chevy intended to convey.

Are you positive that the grade braking only works with the cruise on? When I use the tow/haul mode and not in cruise control it seems to be working.

I should also get used to the manual mode before I find myself coming down a steep Pennsylvania mountain.
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Old 03-21-2016, 04:45 PM   #11
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I use manual mode on hills- up or down (2251- similar rig-6 spd). I try to keep the RPM in the 2500-3500 range. (even though peak torque is at 4200- I don't like to "scream" it)
I use tow/haul mode only when towing my utility trailer (25-2800 lbs) or my Tacoma- 4k lbs and manual setting on hills.
I don't like the computer telling me what to do.
I like to "feel" what is going on-motor/trans/throttle/brake.
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Old 03-22-2016, 02:46 PM   #12
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Yes I am positive about “grade braking” working only with the cruise control on. The information under cruise control in the manual states this. It needs the “what speed” information to react to. And with this knowledge I tend to think that any new downhill roads that you do not know for sure it will handle would be a mistake to be relied on. I would use “m” and select the gearing as needed. The mere fact that if you apply the brake would shut off grade braking and up shift convinces me that I would not be happy with the results.

But using the tow/haul will certainly change shifting points and help on its own.

The “m” position allows you to select highest gear used and can reduce gearing on the fly. Just as Total Loss has stated. Plus giving his feelings about use and rpm’s. I really appreciate the information from both of you.
I am on my first big trip from NJ, and now am out in New Mexico. Will be experiencing some larger mountains soon with the new to me trans and wanted to touch base with some knowledge input about the Chevy six speed and appreciate your replies.
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Old 03-22-2016, 04:59 PM   #13
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I read the manual and it stated that in manual mode- the grade braking will not work.
But it is working if you are manually using the gear selector to aid in your descent braking by using the engine braking manually. You are doing it- not the computer.

I have that descent braking downshift in my company car also.
Gets annoying when it downshifts to a point of the engine screaming just by tapping the brake- IMO.
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Old 03-22-2016, 11:41 PM   #14
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the grade braking works with the cruise control off as well.
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Old 03-23-2016, 10:03 PM   #15
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Just use the gear that keeps you at the speed you want without over reving the engine. Typically I keep mine in 3 or 4th With a good brake controller the trailer brakes will keep enough drag to keep you safe. I try to keep my RPM between 2500 and 3500 if I can.
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Old 03-24-2016, 07:47 AM   #16
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Gets annoying when it downshifts to a point of the engine screaming just by tapping the brake- IMO.[/QUOTE]
Done it many times towing a fifthwheel - WHAT A THRILL !
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Old 03-26-2016, 04:28 PM   #17
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Grade assist

My tv is 2014 highcountry 1/2 ton with the tow package and tow FR evo 200rd. Still a newbie from S Cal. Only been out a couple times so far, but gone up and down a good grade by home. I haven't used the M mode and not sure I understand how it works. Can you just shift from D to M going 55 miles an hour? I due use tow haul when I am pulling my trailer. The grade assist does come on when going down and never use the Cruze control. Heading to S Dakoda June 4 for 3-4 weeks, so I imagine I'll learn a lot then. Do get lots of great information from this site.
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Old 03-26-2016, 04:58 PM   #18
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Quote:
Originally Posted by poorbuthappy View Post
the grade braking works with the cruise control off as well.
That's correct; at least it is for my 2015 Silverado 1500. Now if this is true for a MOTORHOME? Not sure. But on the trucks it engages without cruise.

However, there are different grade braking modes and that might be the misunderstood part;

One is "Normal Grade Braking," and there is "Tow Haul Mode Grade Braking," and then there is "Cruise Grade Braking System."

I believe that is why some say it only works in Cruise, and some, like me, says it works without cruise.

All page numbers are from a 2015 Silverado owner's manual PDF file.
From my manual..
Page 9-36/9-37
Normal Mode Grade Braking

If equipped with a gasoline engine
and an automatic transmission,
Normal Mode Grade Braking is
enabled when the vehicle is started,
but is not enabled in Range
Selection Mode.

To disable or enable Normal Mode
Grade Braking within the current
ignition key cycle, press and hold
the Tow/Haul button for
five seconds.

For other forms of grade braking,
see Tow/Haul Mode on page 9-39
and Cruise Control on page 9-57.


Page 9-40
Tow/Haul Mode Grade Braking

Tow/Haul Mode Grade Braking is
only enabled while the Tow/Haul
Mode is selected and the vehicle is
not in the Range Selection Mode.

For other forms of grade braking,
see Automatic Transmission on
page 9-34 and Cruise Control on
page 9-57.

Page 9-59
CRUISE CONTROL
While going downhill:

. Vehicles with a 6-speed
automatic transmission and a
gasoline engine have Cruise
Grade Braking to help maintain
driver selected speed.

Cruise Grade Braking is enabled
when the vehicle is started and
cruise control is active. It is not
enabled in Range Selection
Mode. It assists in maintaining
driver selected speed when
driving on downhill grades by
using the engine and
transmission to slow the vehicle.

For other forms of Grade Braking,
see Automatic Transmission on
page 9-34 ,Tow/Haul Mode on
page 9-39, and Hill Descent Control
(HDC) on page 9-56.

NOTE: DO NOT TRY THE HILL DESCENT CONTROL. Don't believe it will engage, but it is designed for off-road travel and used under 31 mph. I'm guessing if you push the button at 80 mph, the computer will ignore it...I hope.
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Old 03-27-2016, 01:43 PM   #19
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Quote:
Originally Posted by f5moab View Post
That's correct; at least it is for my 2015 Silverado 1500. Now if this is true for a MOTORHOME? Not sure. But on the trucks it engages without cruise.

However, there are different grade braking modes and that might be the misunderstood part;

One is "Normal Grade Braking," and there is "Tow Haul Mode Grade Braking," and then there is "Cruise Grade Braking System."

I believe that is why some say it only works in Cruise, and some, like me, says it works without cruise.

All page numbers are from a 2015 Silverado owner's manual PDF file.
From my manual..
Page 9-36/9-37
Normal Mode Grade Braking

If equipped with a gasoline engine
and an automatic transmission,
Normal Mode Grade Braking is
enabled when the vehicle is started,
but is not enabled in Range
Selection Mode.

To disable or enable Normal Mode
Grade Braking within the current
ignition key cycle, press and hold
the Tow/Haul button for
five seconds.

For other forms of grade braking,
see Tow/Haul Mode on page 9-39
and Cruise Control on page 9-57.


Page 9-40
Tow/Haul Mode Grade Braking

Tow/Haul Mode Grade Braking is
only enabled while the Tow/Haul
Mode is selected and the vehicle is
not in the Range Selection Mode.

For other forms of grade braking,
see Automatic Transmission on
page 9-34 and Cruise Control on
page 9-57.

Page 9-59
CRUISE CONTROL
While going downhill:

. Vehicles with a 6-speed
automatic transmission and a
gasoline engine have Cruise
Grade Braking to help maintain
driver selected speed.

Cruise Grade Braking is enabled
when the vehicle is started and
cruise control is active. It is not
enabled in Range Selection
Mode. It assists in maintaining
driver selected speed when
driving on downhill grades by
using the engine and
transmission to slow the vehicle.

For other forms of Grade Braking,
see Automatic Transmission on
page 9-34 ,Tow/Haul Mode on
page 9-39, and Hill Descent Control
(HDC) on page 9-56.

NOTE: DO NOT TRY THE HILL DESCENT CONTROL. Don't believe it will engage, but it is designed for off-road travel and used under 31 mph. I'm guessing if you push the button at 80 mph, the computer will ignore it...I hope.

FWIW, the info in your Silverado manual is a bit different than the info in my 2012 Chevy Express Van manual. I don't know if the difference is due to upgrades over the years or in the vehicle type.
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Old 03-31-2016, 06:38 PM   #20
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Yes, there were changes between my 13 and 15. But again this last week I prove, at least to myself, there is grade braking WITHOUT cruise control on or in tow mode. Same place every time, coming down from Soldier's summit on Hwy 6.
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