If you’re pulling a heavy camper on dry roads, you can generally turn on tow/haul when you leave and keep it on for the trip. There’s no need to switch it on for every hill and off again when the road flattens out.
When would you leave tow/haul off?
Check the tow/haul instructions for your truck’s model year and engine. Slippery roads and light loads are two situations to look for, but the recommendations depend on the truck.
On slippery roads, follow your truck’s specific warning. The 2026 Ram 1500 owner’s manual, for example, says not to use tow/haul in icy or slippery conditions. The increased engine braking can cause the rear wheels to lose traction and the truck to slide.
With a light trailer, tow/haul may not be recommended. Chevrolet’s 2022 Silverado HD owner’s manual advises against using it when lightly loaded or not towing. It won’t cause damage, but it may reduce fuel economy and make the engine and transmission less pleasant to drive.
A small pop-up behind a heavy-duty pickup may not call for the same setting as a large fifth wheel. Follow your truck’s load recommendations rather than assuming every trailer calls for tow/haul.
What changes when you press the button?
For gas and diesel trucks with automatic transmissions, tow/haul changes when the transmission shifts.
Say you’re pulling your camper along a rolling highway. The truck shifts up, reaches the next rise, and shifts back down. Then it does it again. That back-and-forth shifting is often called gear hunting.
Tow/haul holds the lower gears longer to reduce that cycling. The 2025 Ford F-150 owner’s manual describes moving upshifts to higher engine speeds, along with downshifting to help slow the truck on descents.
So if the engine revs higher than usual before shifting, that can be the setting doing its job.
Reducing repeated shifts also helps manage transmission heat. Ram lists a lower risk of overheating from excessive shifting as one of the reasons to use tow/haul.
What about flat highways and traffic?
A heavy camper still puts a load on the truck on level ground. Reaching a flat highway doesn’t, by itself, mean you need to turn tow/haul off.
Chevrolet also lists stop-and-go traffic and busy parking lots as places where tow/haul helps with a heavy trailer or load.
How it helps going downhill
On a descent, tow/haul can downshift so the engine and transmission help slow the rig. You may hear the engine rev up even with your foot off the gas.
Ford’s RV and Trailer Towing Guide recommends tow/haul with its TorqShift transmission to help control downhill speed. It also advises downshifting to help with braking on steep grades.
For a long or steep descent, you may still need to select a lower gear yourself with your truck’s gear-selection controls. Tow/haul helps slow you down, but it won’t always hold the speed you started at.
If your diesel has an exhaust brake, check how it works with tow/haul. Some trucks have a separate exhaust-brake button, while others activate exhaust braking when tow/haul is selected.
Check the setting after a fuel stop
Before you pull out, turn on tow/haul with your truck’s button or drive-mode control and look for the indicator on the dash.
After shutting off the engine, don’t assume the setting is still on. Ram’s instructions say you have to select tow/haul again at each startup. Chevrolet’s 2019 Silverado owner’s manual describes keeping it on if the truck is restarted within four hours.
Some older GM models, including the 2000 Silverado, reset tow/haul at every startup. Following a fuel or lunch stop, glance at the dash before pulling back onto the road.
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