Trailer Brake issues

[Three Gs]

Hello all,
I am the owner of a 16 ft Scamp. I recently purchased a 2018 Subaru Outback which I had the hitch ( with standard 4 prong electrical) installed at time of purchase. The dealership doesn't install Trailer brakes, so I took it to a local trailer dealer in my area. Used my Prodigy P2 from my previous Subaru and had them install the wiring and new plug next to the hitch.


The car check engine light came on after returning from a 500 mile trip. I took it to the dealership and they replaced the Co2 censor. Check engine light came on again after this. Finally after 3rd trip to dealership, they diagnosed that the trailer brake had been incorrectly hooked up by the Trailer dealer. Trailer dealer meanwhile asked why the check engine light didn't come on immediately after installation and just now after more than 30 days ( which is beyond his warranty period). Dealership charged me 3 hours labor when wiring problem uncovered. Trailer dealer won't return calls!

Dealership corrected wiring problem. 40 miles on the road and check engine light came back on.

Return car to dealership... replaced the ECM (computer)this time. Check engine light back on , rear wiper not working.
Back to dealer this time to replace Co2 and a multitude of other censors that I don't understand. Also determined the trailer company had installed brake wire into rear wiper fuse. This time when I picked up car ( after being in the shop for 7 days), they now have disconnected the trailer brake. So I now have no trailer brake and no idea how to proceed.

We are watching to see if we can isolate the source of the problem... car internal, trailer brake ( Prodigy) or wiring. Wondering if anyone has heard of problems with the new Subarus and trailer brakes... or has any ideas what might be going on.

[Jon in AZ]

We heard some chatter that new Outbacks are incompatible with traditional wired brake controllers. Scamp is selling and installing a new type of unit called the Autowbrake. It uses a trailer-mounted inertial controller with a remote to apply brakes independently.

[Glenn Baglo]

Originally Posted by Jon in AZ

We heard some chatter that new Subarus are incompatible with traditional wired brake controllers.

That's brilliant now that they have a vehicle with some tow capacity.

[Thinh]

...I had almost similar issues with my Toyota Matrix. Only difference is I wired it myself and finally fixed it myself, too. Make it short, I installed the brake controller right under-neath and closed to the steering column of Toyota. Towing and camping for several years and it worked beautiful, no issues whatsoever. Until one day, my wife drive my Toyota and since then it was her everyday car . Due to my wife's legs are longer than ...mine. So she hit the brake controller with her knees frequently without towing anything. One day, ABS, engine lights came on to the point she could not control the car no more, she pulled over the road and took the cab home. Done my work, with the help of a friend, I came, unplug brake controller of Toyota and drove it home ( with engine light, ABS light ON). After 1 hour of dismantling wirings of brake controller, inspecting, checking and clear codes...The Toyota has been working fine since. Luckily I got other 2 towing vehicles on stand-by mode so decided to give her little Toyota retiring from...towing. The car is still driven by her everyday now. My story. Share...

[Jon in AZ]

Originally Posted by Glenn Baglo

That's brilliant now that they have a vehicle with some tow capacity.

The chatter applied specifically to the Outback. I haven't heard anything about towing set-up on the Ascent. I edited my earlier post to clarify that.

[Gompka]

Originally Posted by Jon in AZ

The chatter applied specifically to the Outback. I haven't heard anything about towing set-up on the Ascent. I edited my earlier post to clarify that.

Jon technically the brake cobtroller, at least in the case of the Prodigy proportional units, is a stand alone device. it connects directly to the battery and passes the current directly to the trailer. the only reason the brake controller taps into the cars brake switch is so that the brake lights are activated when you manually switch on the brake controller with its lever. So technically in 90% of situations it won't really hurt to leave that wire off, especially if it is causing problems. At that point the brake controller is its own entity. Going deeper in on the subject of the brake switch, I know some new cars require you to install a diode because the car does not like the +12v brake switch signal backfed into the brake switch circuit. I believe the new toyoya highlander vehicles have this issue.

[Jon in AZ]

Originally Posted by Gompka

Jon technically the brake cobtroller, at least in the case of the Prodigy proportional units, is a stand alone device. it connects directly to the battery and passes the current directly to the trailer. the only reason the brake controller taps into the cars brake switch is so that the brake lights are activated when you manually switch on the brake controller with its lever. So technically in 90% of situations it won't really hurt to leave that wire off, especially if it is causing problems. At that point the brake controller is its own entity. Going deeper in on the subject of the brake switch, I know some new cars require you to install a diode because the car does not like the +12v brake switch signal backfed into the brake switch circuit. I believe the new toyoya highlander vehicles have this issue.

More than I know, David. There was a lengthy discussion some months ago, but I was unable to locate it.

Seems to me any vehicle with a tow rating high enough that the manufacturer specifies trailer brakes ought to make provision for a built-in controller or a connection port for an aftermarket unit.

In my Barbie world... [emoji57]

I do have concerns about towing a 16'er with an Outback even with brakes. They typically weigh 2400-2600 pounds loaded with 250-300 pounds tongue weight. The Outback has a tongue weight limit of 200 pounds. That's without cargo or back seat passengers.

[David Tilston]

Originally Posted by Gompka

Jon technically the brake cobtroller, at least in the case of the Prodigy proportional units, is a stand alone device. it connects directly to the battery and passes the current directly to the trailer. the only reason the brake controller taps into the cars brake switch is so that the brake lights are activated when you manually switch on the brake controller with its lever. So technically in 90% of situations it won't really hurt to leave that wire off, especially if it is causing problems. At that point the brake controller is its own entity. Going deeper in on the subject of the brake switch, I know some new cars require you to install a diode because the car does not like the +12v brake switch signal backfed into the brake switch circuit. I believe the new toyoya highlander vehicles have this issue.

Are you saying that the brake pedal connection is optional? That is news to me. It is my understanding that, while they sense acceleration, all the Prodigy controllers are activated by the brake switch. Otherwise they are nonactive. Am I wrong on this?

[John in Santa Cruz]

on a bunch of newer vehicles, you need to add a diode to the wire that goes to the brake pedal switch circuit to prevent weirdness like you describe.

[John in Santa Cruz]

Originally Posted by David Tilston

Are you saying that the brake pedal connection is optional? That is news to me. It is my understanding that, while they sense acceleration, all the Prodigy controllers are activated by the brake switch. Otherwise they are nonactive. Am I wrong on this?

you are correct. but, its the inverse function gompka described thats probably triggering the fault.

[Jon in AZ]

If memory serves, the Highlander issue occurred only when the trailer brakes were applied independently of the vehicle brakes, as when testing or adjusting the brakes. The controller sends a signal to the brake pedal circuit in order to illuminate the brake lights. That signal caused a check engine fault. The one-way diode prevents that signal.

The signal the other direction serves to activate the controller when the pedal is depressed. Deceleration only determines the amount of trailer braking applied. In the Highlander situation, normal operation of the brake controller in conjunction with vehicle brakes did not trigger a fault.

At least that's how I'm understanding it, and I'm not an electrician.

I have yet to hear from a 2018 Outback owner who has successfully installed a wired controller. I can't tell for sure if the issue is the same as the Highlander or not, because apparently other mistakes were made in this case.

Curious to hear more.

[Gompka]

Originally Posted by Gompka

Jon technically the brake cobtroller, at least in the case of the Prodigy proportional units, is a stand alone device. it connects directly to the battery and passes the current directly to the trailer. At that point the brake controller is its own entity. Going deeper in on the subject of the brake switch, I know some new cars require you to install a diode because the car does not like the +12v brake switch signal backfed into the brake switch circuit. I believe the new Toyota highlander vehicles have this issue.

Somehow what I was thinking and what I wrote were not the same thing about the brake wire, it is indeed required. What I meant to say is that:
The stop light switch wire only lets the controller know you have pressed the brakes. After that the rest of the math is done internally by the controller and its accelerator. So unless you use the controller manually in which case it sends a +12 to the stop light switch to turn on your brake lights, the brake controller does not modify or add to any signals to the car.

So in conclusion if the brake controller is wired properly (to the battery), and not used in manual mode, there is no reason it can cause any check engine lights or other car problems because it is its own thing, its like plugging a usb charger into the cigarette outlet, it just takes power from battery and passes it to your phone for example.

Disconnecting the controller and getting the vehicle running correctly first, and then afterwards making sure the brake controller is connected properly should alleviate the issues you are having. Don't let the dealership tell you the brake controller broke something, tell them you want written proof if they accuse the brake controller. Even if the brake controller was wired incorrectly to the wiper circuit, the most damage that would happen is the wiper fuse would blow and the brake controller would stop working.

[Darral T.]

So no one- including both dealers- have researched (AND Prodigy) to see if a "diode" would stop the "feedback" into the wiring system??

I think this would be some VERY sound advice for new TOW vehicle purchasers- DO NOT buy a vehicle to tow with unless it comes with its own TOW "PACKAGE"!

I'd be afraid of "voiding" the warranty and you may want to refer to the Owner's manual for just that info!

For what it's worth, I installed the Tekonsha Prodigy on my 99 Nissan myself and have not had ONE min problem with it OR the trailer in over 8 yrs.

[Gompka]

Originally Posted by Darral T.

So no one- including both dealers- have researched (AND Prodigy) to see if a "diode" would stop the "feedback" into the wiring system??

I think this would be some VERY sound advice for new TOW vehicle purchasers- DO NOT buy a vehicle to tow with unless it comes with its own TOW "PACKAGE"!

I'd be afraid of "voiding" the warranty and you may want to refer to the Owner's manual for just that info!

For what it's worth, I installed the Tekonsha Prodigy on my 99 Nissan myself and have not had ONE min problem with it OR the trailer in over 8 yrs.

I wouldn't be afraid of voiding warranty, the dealer has to prove that something you did caused a failure and even then they can limit warranty on only that specific part. So they can't say your engine blew because you wired the brake controller incorrectly, but they can charge you for a new stop light switch.

[Darwin Maring]

looks to me like your dealer screwed you really good by replacing possibly good items.

[Gerry Kiernan]

The simplest solution might be to install "surge brakes". They have a hydraulic cylinder mounted to the tongue of the trailer, and the tongue can float back and forth a little bit. When you brake the trailer pushes on the tongue, which pushes on the hydraulic cylinder, and actuates the trailer brakes. Many boat trailers are equipped with these as electrical brakes and water don't mix all that well.

[Gerry Kiernan]

Most foreign built vehicles have separate bulbs for the brake lights, and the signal lights. American built vehicles use one bulb for both purposes. Assuming the trailer to be American built, this likely where the problem arises.

[Jon in AZ]

Originally Posted by Gerry Kiernan

The simplest solution might be to install "surge brakes"...

The Autowbrake system is an electric version of surge brakes. It resides entirely on the trailer (except for the remote) and activates on deceleration alone without requiring input from the vehicle brake system. Advantages are (1) it uses the existing electric trailer brakes, and (2) it provides a means to activate the trailer brakes independently to stop sway.

[stevebaz]

use the prodigy rf brake controller.

Tekonsha - Trailer Brake Control - Proportional

[John in Santa Cruz]

Originally Posted by Gerry Kiernan

Most foreign built vehicles have separate bulbs for the brake lights, and the signal lights. American built vehicles use one bulb for both purposes. Assuming the trailer to be American built, this likely where the problem arises.

anyone competent wiring a trailer connector, even a 4-pin, to a vehicle like that would use a trailer light controller module such as...

https://www.amazon.com/Hopkins-48925.../dp/B0002Q81XK