I keep seeing where T/H will help shift gears so you can slow vehicle down while descending without riding your brakes. I always use T/H, but I have neve figured out how to engage it to work going down hills. Do you tap the break a couple of times ?
I have copied this from a previous post I made back in Jan. On this topic.
At a very high level, Tow/Haul is effectively preventing the transmission from excessive shifting. It basically prevents the transmission from shifting into the top gear of the transmission. Many transmission in todays truck have at least 1 overdrive gear as the top gear or in some cases 2 overdrives as the top two ratios. These OD ratios are less than a 1:1 ratio and are designed to lower engine rpms to improve fuel mileage. So when the tow haul is engaged, your cruise rpm would in fact be higher at a given speed over the next higher gear at the same speed. The same would apply down hill, you rpms would be higher at a given speed. In most cases Engine Brakes/Exhaust Brakes are in fact more effective at higher rpms than they are at lower ones. Remember this is a high level conversation and there are limits to be concerned with. So it is important to understand the operation of both modes and cause and effect of each on its own and the combination of both in operation at the same time. I am sure this topic would be covered in your owners manual.
Generally speaking the tow haul is targeting uphill operation, to prevent transmission overheating, excessive shifting and that surprise rpm surge that comes with an downshift going up hill.
Also generally speaking the down hill operation would be up to you to request a lower gear to help control your down hill speed. However(before others jump on here😂) when a ram is equipped with a Cummins, they have integrated the tow haul and engine brake feature to help control speeds.
Please refer to your specific owners manual for the details related to your vehicle.
