Pulling a heavy load isn’t as simple as it might appear. If you have an automatic transmission, it needs to operate differently to protect itself and give you better control of the vehicle.
While modern cars and trucks often feature extremely advanced parts and programming, their default setting is usually either fuel economy or a favorable balance between gas mileage and power.
While towing, you need to focus on power. Not doing so would be unsafe and could directly damage your transmission.
Without the tow/haul button, the vehicle could jump into high gears too quickly, leaving it struggling to put power down. This puts unnecessary strain on the gearing system and will make stopping harder. Your car could also accelerate (potentially uncontrollably) while driving downhill.
Manual transmissions do not need a tow/haul button.
Why?
You’re already in complete control of the car’s gears yourself. If your automatic vehicle has a manual sequential selection option, you could also use this instead.
Let’s get started with the guide.
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What Does A Tow/Haul Button Do?
The tow/haul button’s function is unique to each manufacturer. However, broadly, it forces the transmission to stay in a lower gear than usual. As such, the revs will be higher than normal.
Pushing the button – which can usually be done at any moment while driving or stationary – tells the transmission to behave differently. It’s all done electronically and primarily aims to give you better vehicle control and protect the drivetrain.
Tangent: a tow/haul button is essentially the opposite of a snow or ice mode button, which lowers the revs and puts the car in the highest gear possible to increase grip.
What Does The Tow/Haul Button Do? – Increase Safety
Here’s how the tow/haul button makes driving much safer when carrying or towing a heavy load.
What Is Engine Braking?
To explain why the tow/haul button is essential, let’s consider a case study: driving down a steep-ish hill.
No problem, right? Well…
Most automatic transmissions are set to jump into the highest available gear for your speed. This maximizes fuel economy and means you won’t have to spend as much on gas. You’ll have noticed it when you drive downhill – the transmission changes up once, twice, or more times, reducing the revs but meaning you start accelerating.
You’ll probably have been taught to apply the brakes to help control the vehicle’s speed. Maybe someone even advised you to let the car speed up as much as possible – it’s free momentum, so why wouldn’t you?
Well, while you may save a cent on gas, it’s a much more dangerous way to drive. The risk doesn’t match the reward.
Instead of letting the car jump into the highest possible gear, you should force it to stay in a lower one. Think third or fourth – somewhere around there, depending on the car, transmission, and decline rate.
Of course, this isn’t possible in all vehicles – but most automatics should allow you to lock the car into gear in some way or other.
This is the concept of engine braking. When you press the tow/haul button, you increase the revs, thereby permanently increasing the engine braking. Technically, this is always the safest way to drive, whether or not you’re towing.
Keep downshifting until you find the gear that holds the car at approximately the same speed – without using the brake pedal – as you travel downhill.
Engine Braking – What Would Happen If I Didn’t Use The Tow/Haul Button?
So, what would happen if you didn’t use the tow/haul button while heading downhill?
The vehicle essentially weighs much more – depending on the extra load, perhaps double its normal curb weight. Without delving too deeply into mathematical mechanics, this effectively means you need twice the stopping power.
If we’re ignoring engine braking, for the time being, the stopping power is the brakes. You’ll need to press them twice as hard just to maintain a safe speed. However, push them too hard for too long, and they’ll heat up, reducing the friction and leading to brake fade – a hazardous situation.
Now you’re heading downhill, quickly picking up speed, with no way to slow down or stop.
Don’t worry, though; engine braking is on hand to save you through the tow/haul button (or by manual gear selection). It’ll quickly drop the gears, increasing the revs and bringing engine braking into play. At worst, it’ll dramatically slow your downhill acceleration. At best, it may even slow you down.
That’s just one of the reasons why the tow/haul button is so important to use.
What Does The Tow/Haul Button Do? – Protect Your Transmission
So, how does the tow/haul button protect your transmission?
Think back to driving through a hilly area, but this time uphill. When you’re heading up an incline, gravity functions as an extra “load” – it means your vehicle has to pull its weight up the hill.
Do you notice how your transmission has to shift down two or three gears as the revs drop? That’s because you need more power to get up the hill – lower gears. If the car didn’t downshift, it would put the higher gears through enormous strain before the engine would eventually stall.
The same thing happens when accelerating with a significant extra load. If you aren’t in a low enough gear, it puts extra strain on the transmission.
By being in a lower gear to begin with – something the tow/haul button ensures – you’ll have more instant control and protect the transmission.
When Do I Need To Activate The Tow/Haul Button?
Check your owner’s manual. It’ll tell you exactly which weights you should activate tow/haul.
There’s usually no need to use tow/haul if you’re carrying minimal loads. For example, a cabin full of passengers or a washing machine in your truck bed wouldn’t constitute a tow/haul. However, a large horse trailer or a vehicle filled to the brim with builders’ rubble would.
Simply press the button to trigger it. You shouldn’t need to be stopped – it’ll activate (and deactivate) at any time.
When Should I Turn The Tow/Haul Button Off?
Of course, you don’t need to have tow/haul activated as soon as you’ve dropped your load off and returned to everyday conditions.
It also might not be necessary to have it on while highway driving. Once you’ve reached fast enough speeds, most transmissions will work fine in their highest gear regardless. You’ll save some fuel by switching the tow/haul button off.
However, it’s best to leave it alone if you’re liable to forget to turn it back on as soon as you reach hills, traffic, or come off the highway.
In general, turning tow/haul on and leaving it until you unload or unhook the trailer is a good idea. While you’ll use more fuel, it’s safer and protects your transmission against unnecessary mechanical strain.
Is The Tow/Haul Button Expensive To Fix?
If your tow/haul button stops working, you’ll notice that nothing changes when you press it. More obviously, the dashboard indicator won’t come on.
Since the tow/haul button is all electronic, it might need to be completely reprogrammed – if you’re unlucky. However, many owners report that the wires themselves commonly physically break. The gear-shifting mechanism pinches and snaps them.
Thankfully, there’s only one set of wires leading to and from the tow/haul button. A technician will remove the panels under the dashboard and steering column to access them before stripping the two snapped-off ends and splicing them back together. Materials will be minimal, and you should expect to pay up to an hour’s labor.
Alternatively, you might like to replace the entire gear shift lever. Expect the parts to be around $100 to $120 with a couple of hours’ labor, most likely coming to between $200 and $350 in total.
If you’re unlucky enough to need some reprogramming, the cost can be much more. There could be other issues at play, too. Expect to be paying somewhere in the high hundreds for a specialist to reprogram your ECU.
Concluding Thoughts
The tow/haul button is essential for transporting heavy loads. Check your owner’s manual for the exact weights when you’ll need to switch it on.
The tow/haul button forces your car or truck’s automatic transmission to select lower gears. This increases the revs and, therefore, power output.
Using the button correctly will put less stress on your automatic transmission and drive much more safely due to significantly more engine braking.
It might be a small button, but tow/haul has a vital role. Yes, your fuel economy won’t be so good as if you turn it off.
However, compare it to the cost of damaging your transmission and the rebuild or replacement that would stem from that, and you’ll quickly conclude that a few extra dollars per hundred miles isn’t too much of an ask.
