Rookie Diesel Owner

[JaycoAngel]

Posting this for my hubby:
I recently bought a 2014 GMC Duramax Diesel. Previously pulled
With a big block Chevy. Not sure what gear to use when pulling:
Drive or Manual and I am not sure about the tow button (I am assuming
I use the tow button (I am assuming whenever I am towing).

Would appreciate any advice.

[2112]

Never mind. I didn't realize this is an old thread

[SweetLou]

When I tow, its in tow/haul, even when not towing I do this. I use the exhaust brake when towing and when heavy, its full on. I use the manual mode when heading up the grades and I know from previous trucks I owned which had the exhaust temps monitored to try and keep it in the right gear and slow it down heading up grades to keep exhaust gas temps around 1100. She will purr all the way up. If you see engine temps rising to fast, down shift and slow it down or you will over heat, and by all means turn off the AC

[RAS43]

freddmc wrote:
"would read the owners manual if we had one. Dealer has ordered one for us as it came without."

Comments like this really disturb me. I would have said to the dealer"look, I just paid you MANY thousands of dollars for a truck that SHOULD have come with a $10 manual and you want me to wait while you order one.Get one out of another truck on your lot and order a new one for it OR, keep the truck"

The OP's friend didn't buy a new truck so the lack of an owners manual can happen. The dealer is responding correctly, IMO.

[ksss]

When I tow heavy I use manual going up mountain passes. The pickup runs cooler when I shift myself, only an issue when running heavy on steep passes. Your '14 does not have an exhaust brake I don't believe. I have an 06 LBZ 3500 that I had programed to grade brake when in tow/haul mode. It uses the variable vane turbo just like the newer pickups do for the exhaust brake. If you would want to, you can have your '14 programed to do the same thing. It is not as aggressive as the new pickups but it is pretty good.

[freddmc]

"would read the owners manual if we had one. Dealer has ordered one for us as it came without."

Comments like this really disturb me. I would have said to the dealer"look, I just paid you MANY thousands of dollars for a truck that SHOULD have come with a $10 manual and you want me to wait while you order one.Get one out of another truck on your lot and order a new one for it OR, keep the truck"

[Thom02099]

I have the classic 2007 GMC Sierra SLE 3500 dually. Most of the time I just put it in Drive and let the Duramax/Allison do what they do best. However, in the mountains of Colorado, and on a recent trip in October at various elevations up to 11000 feet, I selected Manual mode and chose my gears, for going up and going down passes. If I went up a pass in 3rd, I also went down in 3rd (Wolf Creek Pass). Always in Tow/Haul mode.

[ppine]

Learn to drive by watching your tachometer. For pulling it is important to have the right amount of turns on your engine. Don't lug a diesel and expect it to perform at its best in overdrive going up hill unless you are going fast.

[ppine]

You have the right rig to tow with. Welcome to the club.

Coming out of the gate towing 14,000 pounds might be a little optimistic.

[JaycoAngel]

Thank you!

[HTElectrical]

Adrenaline Truck Performance wrote:
With tow/haul mode engaged, this tells the TCM (transmission control module) that the shift patterns need to be changed. Generally it will raise all of your part throttle shifting by 300-400 rpms. This will help keep the engine up higher in its power band when a shift is completed and improve acceleration when towing a heavy load.

With tow/haul mode engaged the torque converter will lock much sooner. Normally, the TC (torque converter) will lock in either 4th or 5th gear at around 50mph. With tow/haul engaged, the TC will lock in 2nd gear at about 25mph.

What’s the benefit? Once locked up, all of the engine power will be passed through the transmission instead of being lost by the TC when it is only using fluid coupling to transfer power. You will notice more responsive acceleration and it will help to keep the transmission fluid cooler.

Finally, with the tow haul mode engaged, downshifting will be much more aggressive during hard braking. With a heavy trailer, it is always nice to have as much stopping power as possible.

[bob213]

I don't believe the 2005 has an exhaust brake. Putting the transmission into tow/haul helps with downgrades but I believe it's the transmission doing the work. An exhaust brake can be programmed in with an external programmer like EFI.

[azdryheat]

These replies are correct. I always use tow/haul mode when my heavy trailer is hooked up. When I'm in the mountains I like to put the tranny in manual so I can keep it in (usually) 4th gear when climbing. The exhaust brake works ok.

[Old-Biscuit]

Get your own copy of manual and info.......HERE/CLICKY

[bailer6334]

The simple answer is always use the exhaust brake regardless if towing or not. Use Tow haul whenever towing.