A safety feature that could contribute to an accident

[overlander63]

A few days ago, a customer purchased a new travel trailer, and brought their nearly-new acura MDX SUV in for hitch work and brake controller installation. After hithing them up, we took a quick test drive, at which time I explained how to stop trailer sway by using the throttle and manual lever on the brake controller. For those that aren't aware, if the trailer begins to sway, you are supposed to manually apply the trailer brakes and press the accelerator on the tow vehicle. the combination of drag from the brakes and accelertion will stop the sway, at which time you can pull over, stop, check why the trailer swayed, and execute an underwear change, if needed.
Well, guess what? When you apply the trailer brakes, or touch the brake pedal at all, the throttle drops to idle, and there is nothing you can do about it. That can quickly become a Very Bad Thing if you are in the middle of the trailer trying to pass you. The last thing you want is for the tow vehicle to slow down while this is happening.
This appears to be a safety feature instituted after the Toyota runaway incidents, and, while I don't have a list of vehicles equipped with this "feature", it could begin to have more widespread use as more and more manufacturers decide this is a way to prevent lawsuits.
While swaying Airstreams are not common, it does happen, and it would be very wise to check your tow vehicle to see if it has this "feature", so you won't be caught by surprise in an emergency. It's bad enough if a trailer starts swaying, but then to find out at that moment your primary response is useless could well be a disaster.
So, take a moment the next time you are out in your (especially newer) tow vehicle to see if yours is one of these. Simply check behind you to make sure no one is following closely, and lightly apply the brakes while holding the throttle steady. If all goes well, you are good, but if suddenly the engine drops to idle, you will need to make a new contingency plan for the possibility of correcting trailer sway.

[rmkrum]

Was that brake controller an aftermarket one like a Prodigy 2 with just a 4-wire connection, or was it the integrated brake controller connected to the electrical system/computer of the vehicle?

I suspect an aftermarket unit, unless it has a circuit that lights the brake lights when you hit the manual lever, may not exhibit that behavior--at least I hope not, since that is my setup.

I need to check this soon, as I have Toyota tow vehicles of recent vintage, and this could be a real nightmare--even with a PP hitch setup that I get to install this weekend.

Talk about unintended consequences!!!

[jdalrymple]

How does the car know the trailer brakes have been applied, if done so manually at the brake controller?



Regards,

JD

[overlander63]

Originally Posted by rmkrum

Was that brake controller an aftermarket one like a Prodigy 2 with just a 4-wire connection, or was it the integrated brake controller connected to the electrical system/computer of the vehicle?

I suspect an aftermarket unit, unless it has a circuit that lights the brake lights when you hit the manual lever, may not exhibit that behavior--at least I hope not, since that is my setup.

I need to check this soon, as I have Toyota tow vehicles of recent vintage, and this could be a real nightmare--even with a PP hitch setup that I get to install this weekend.

Talk about unintended consequences!!!

It is a Prodigy P2, but the throttle will return to idle if you tap the brake pedal as well. It was wired using the harness supplied by Acura, according to their directions.
I have checked, and there are, as far as a quick search, at least a couple of sporty cars with this feature. It makes it impossible to drive and corner using the traditional heel and toe method of braking and cornering.

[overlander63]

Originally Posted by jdalrymple

How does the car know the trailer brakes have been applied, if done so manually at the brake controller?



Regards,

JD

Many brake controllers will activate the brake lights when the manual lever is applied.

[rmkrum]

OK, since I have a Prodigy 2 set up with the factory harness in our Toyota Tacoma TVs (2008 and 2012) now I know I may have an issue...I will test that out ASAP.

Yet another reason I'm darn glad I spent the big $ for a PP (or HAHA type) sway PREVENTION hitch--thank you very much for helping justify the cost of the PP P3, and probably making my life a lot longer...never mind the probability of needing a skivvies swap-out...

Moderators: Others need to look at this data as well--can you cross-post this to the appropriate hitch and TV forums? This could be a major source of accidents with these modern vehicles....

[overlander63]

Originally Posted by rmkrum

Moderators: Others need to look at this data as well--can you cross-post this to the appropriate hitch and TV forums? This could be a major source of accidents with these modern vehicles....

At the very least, make it a "sticky", so it will be the first thing seen in the subforum.

[DKB_SATX]

Interesting. I was aware of the idle-on-braking "feature" added when people as a group seemed to forget how to use Neutral (and cars-without-keys made it more complicated to switch off the engine), but it never occurred to me that the manual lever on a brake controller would trigger it, since you're not applying the TV brakes. Some highly-sensitive monitoring of voltage in the TV brake light circuit? Or did you look and see that it was lighting the brake lights?

Perhaps recommend that they try a P3. I know that at least in my F150, the P3 manual lever doesn't trigger the TV brake lights OR the trailer brake lights.

[overlander63]

Here's a bit of light reading about others' take on the problem. While not towing related, it does confirm the issue:

Throttle cut off when you brake on 2012 MDX - Acura MDX Forum : Acura MDX SUV Forums

http://www.thesmokingtire.com/2012/p...ottle-cut-off/

http://www.audizine.com/forum/showth...dal-Depression

http://www.autoblog.com/2012/04/12/n...o-official-sa/

[ROBERT CROSS]

Glad I have no plans for replacing our TV....


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Bob

[dkottum]

All the more reason to consider a Hensley/ProPride style hitch so there is no sway to correct. Not expensive in the overall cost of late model tow vehicle and Airstream.

doug

[reinergirl]

Whoa this is not good news! I assume this safety feature would be in the new Tundras? Can anyone confirm?

[cwf]

When trailer connected should override that "feature".... Time for software update...again ?

[ROBERT CROSS]

Originally Posted by cwf

When trailer connected should override that "feature".... Time for software update...again ?

If a market develops maybe the aftermarket will supply the necessary software.

Bob

[srpuywa]

my 10 year old vw diesel jetta wagon goes to idle when the brake pedal is pushed, I think it's part of the ECU programming

[polarlyse]

On the plus side this programming feature just might go towards correcting the drivers that like to use the left foot to ride the brake. You know, the ones that are constantly flashing their brake lights while driving. I just hate being behind one of them.

[DKB_SATX]

Originally Posted by polarlyse

On the plus side this programming feature just might go towards correcting the drivers that like to use the left foot to ride the brake. You know, the ones that are constantly flashing their brake lights while driving. I just hate being behind one of them.

Nah, they'll just be bringing their vehicle into the dealer all the time complaining that it "stalls" or "stumbles" on the highway ALL the time, and will be angry that the tech can't duplicate it.