Downhill Towing 12M lb 5th Wheel

[Cougar]

I have a 2008 Chevy 2500HD diesel with factory towing package. Will be traveling East on I-26 from TN-NC state line to Asheville. How should I set my gear shift lever for best downhill speed control. I normally set Tow Mode and shift lever in D. Do I need to use the M setting? I have read the manual and it is as clear as mud. Can anyone help?

[DmaxMaverick]

Tow mode and D. Unless you get bored and want to fiddle with shifting. If Tow mode doesn't control speed to your liking, you can shift to M and shift manually. Grade braking is pretty effective, most of the time. There are too many variables to limit it to a 'one size fits all' answer.

[Cougar]

Thanks, Maverick.

Is this with cruise control off?

[DmaxMaverick]

Grade braking doesn't work with cruise on a 2008. It's fine, otherwise. Once you apply the brakes on a downgrade (which is the first step to engage grade braking), the cruise turns off, anyway. If you are using a power adder (Edge, etc.), using cruise can cause transmission issues/problems with heavier loads and grades. If you are stock, no worries. In most cases, it's better to let the computer do its job. Use the service brakes to maintain the speed you want, and grade braking should catch on quickly and attempt to maintain that speed.

[Roy W]

I know the downhill grade you speak of, east of Ashville on I-26. On my '05, I disengage OD and let towhaul and service brakes control my downhill braking. I always found it much more effective if I slowed down considerably, maybe to 40mph at the crest, and then maintained that down the mountain. Much easier than starting out faster and then trying to decrease my speed.