Hello, folks. Been an RV'er for a little over two years, and had an experience about seven months ago that prompted me to join this forum just to get your thoughts on it. I grew up towing EVERYTHING on farms and spent a career in the military driving heavy equipment, so when it came time for a new family adventure I salivated at the thought of cruising around the country towing a small house! I needed something that would pull the TT well, but also have room for two teenagers and a set of 2 year-old twins. After much research I outfitted the crew with a 2012 Suburban with full towing package, a Tekonsha P2 brake controller, and a 32' Coachmen Freedom Express. Two years down the road and I love, love, love all three. I am pretty good at operating this size rig, but like any bonehead that has developed a level of skill I got a little over-confident on a long trip, and we set out with full water tanks a little heavier than normal. We were going to boondock at a Wal-Mart the first night, and I wanted a shower the next morning. (Stupid. Now I know.) About 20 miles down the road, I had to move left in the lane to avoid a recap in the road and it started a sway that despite all my concentration kept amplifying and within a few seconds it became obvious that I was in trouble. The sway got worse and worse until it was more like a whiplash effect and I was already starting to decide which side of the interstate I wanted to go off. Suddenly there was a loud groaning noise and the trailer snatched the Suburban back straight. The noise went away and I was driving serenely along my merry way again. After the shakes went away and I finished my thanksgiving prayers, I evaluated all the sensations I felt and it was pretty obvious that the trailer brakes had activated to stop the sway. After some limited research however, I have not been able to figure out if this was a safety feature of the brake controller or the Suburban. Can anyone shed a little light for me?

:) Hi, you might never figure out what happened, but be very glad that it did.

The sway control came out in 2013 on the trucks.....your 2012 Burb may have it, or some version of it. That being said I did not think the trailer brakes would be part of the equation without the factory brake controller. When it activates it will scare the hell out of you. I once hit ice on an off ramp going down grade while coming to a stop. No fun when you glance in the right mirror and see the side of the trailer at about a 30 degree angle. The system kicked in and straightened the rig right out.STABILTRAK VIDEOI do not believe the P2 has a sway detection feature? I know it can apply more voltage when it senses hard deceleration but nowhere on Tekonshas site do they mention it can detect sway and apply the trailer brakes all by itself.

I do not know enough about your setup to know why the brakes applied. I had my sway education decades ago when I loaded 4 heavy items I'd bought into the back of my Airstream trailer. At about 45 mph it started to try and take me to the scene of the accident. Fortunately I knew enough to apply the trailer brakes while still accelerating. The increased tongue weight stopped the sway and then with the brakes still on I pulled over and moved 2 of the items to the front solving the problem.Since then I have pulled hundreds of loads making sure I position so I have plenty of tongue weight, BUT I still give the trailer a wiggle at 45 mph with my hand on the brake control to see if it's going to get worse. Only once have I stAnother load was a building longer than the trailer and to get enough tongue weight I had to put two 55 gallon drums of water in the front of the building. I do not think you can have too much tongue weight.

Do you have the popular groan and jerk, stick and slip, steel on steel sway control hitch?

Sway Control - Who Saved the Day? | Good Sam Community

BurbMan
Explorer II
Feb 26, 2018
LOL Ben you said what I was thinking, these complicated features work great until they don't, the complexity of vehicles is rapidly outstripping the ability of dealer techs to repair them.

My personal preference is to have the TT brakes lead the TV brakes, mainly to manage the Hensley "bump". I would agree that controllers that use a hydraulic pressure sensor to vary brake voltage are not as good as accelerometer-based units, regardless of cost.

Two scenarios: First, if I downshift the transmission to provide engine braking on a downhill grade, I only need to press the pedal lightly to wake up the P2, then it will sense I am slowing down and apply the TT brakes. I don't want to have to apply the TV brakes with enough pressure top activate the TT brakes, that's the whole reason for downshifting the transmission.

Second, if I stomp on the TV brakes on ice, I will build great line pressure but the ABS will modulate pressure to the wheels to avoid a skid. In this scenario, the TT wheels will be locked up based on the pedal pressure I am exerting.

Hopefully an OEM controller would be integrated enough to override its basic line pressure input based on ABS and transmission inputs. It would also seem to me that the OEMs that market some form of "trailer sway control" or "stability" must be using some type of accelerometer to sense lateral movement, along with input from the steering angle sensor, that would be indicative of sway and apply the TT brakes.

Interesting side conversation while we wait for the OP to check his trailer to see if he has some type of electronic sway control installed on it. I'll need to do more research on these controllers when I am ready to buy a truck, it's not a given that one would be better than P2.

4bamayoungs wrote:
BurbMan wrote:
Question: did you buy your trailer new or used? The reason I ask is that if used, the previous owner may have had an electronic sway control installed. These are motion-sensing gyro devices that will activate the trailer brakes when a sway condition is detected.

Link to Dexter Sway control

Link to Hayes Electronic Sway Control

If you felt like the trailer braes activated, they very well may have. The groaning you heard would have been weight distributing hitch straightening out suddenly in response to the trailer brakes coming on.

If you bought the rig used, the previous owner may have had one of these installed and that info wasn't passed along as part of the resale to you.

Interesting. I bought it used from a dealer. The trailer is at a storage lot, but I’ll make a trip out there and look around.
Lynnmor
Explorer
Feb 26, 2018
BenK wrote:
And all of those old MC PSI based controllers are no longer on the market...

Like accelerometer based much better over MC PSI sensed

All of the braking system designed in an earlier career used fluid PSI sensors and most all of those sensors leaked over time. First they became flaky...then intermittent...then failure where fluid would leak all over the place. Granted, it was circa 1970's-1980's and maybe the sensor package is better...but they still work the same way

I already explained that the pressure sensed controllers didn't sell because they weren't cheap. People and dealers want cheap and easy.

The old hydraulic units had no sensor, the brake fluid operated a hydraulic cylinder that was connected to a rheostat. I still have one on my 39 year old van, and it hasn't leaked yet.

The pressure sensing controllers from brakesmart and MaxBrake used a transducer, that had no moving parts, to measure the brake fluid pressure. That sensed pressure determines how much current is applied to the electric brakes, which is how the system closely brakes according to the drivers foot pressure.

I still have a Brakesmart just in case it will ever be needed. I actually liked it better than the OEM units because it didn't reduce braking at very slow speeds.

The OEM units factory installed today, use a transducer screwed right into the hydraulic system and they work very well.
BenK
Explorer
Feb 26, 2018
And all of those old MC PSI based controllers are no longer on the market...

Like accelerometer based much better over MC PSI sensed

All of the braking system designed in an earlier career used fluid PSI sensors and most all of those sensors leaked over time. First they became flaky...then intermittent...then failure where fluid would leak all over the place. Granted, it was circa 1970's-1980's and maybe the sensor package is better...but they still work the same way

Normally agree with Don 100%, but on this...differ because I don't like "highly integrated" anything...even an all in one printer/copier/fax/scanner. Based on another old, associated, career in controls/automation/process control/robotics in the industrial sector

If anyone of those functions of the 'highly integrated' system(s) fails or become flacky...it will take down *ALL* of the other functions

Trying to diag...even with the built in self diagnostics...has most techs just swipe out modules until it functions again (some what)...to leave the root cause still there

Think most who have had problems with their P2/P3 did not have their system dialed in right...enough...or there were other underlying issues that needed fixing before dialing their P2/P3...IMHO their complaints of bucking, jerking, etc are mis-adjusted something or other.

The 'seamless' of the IBC's has the build up of PSI become the lead braking of the trailer before the pedal travels far enough to develop enough MC PSI to get the TV into the game. I like that I can stop the whole setup with just a touch of the brake pedal and no more.

Why am always manually adjusting trailer brakes during the trip and cool for me, as I'd rather that then the TV doing most of the braking

Personal choice and buy what you like.
Lynnmor
Explorer
Feb 26, 2018
BurbMan wrote:
Lynnmor wrote:
The day of accelerometer controlled brake controls needs to come to an end. Brakes should be controlled by the driver, not brake light switches, and the ability of the tow vehicle to decelerate... or not. Talking about milliseconds of "lead" time, is meaningless. Truck manufacturers have installed brake controllers that are far superior than the aftermarket guesswork controllers.

OK so you know you are describing how accelerometer-controlled brake controls work, right? How do you think OEM controllers work? Same as the prodigy, but that have the advantage of being engineered into factory ABS and other functions.

You may be confusing the older "timed" controls that were common before the accelerometer chip became mainstream.

Obviously you don't tow a big trailer or you wouldn't think that the lead time provided by the P2 is "meaningless".

I would agree that OEM integrated controllers are better, but they have only been available for a few years. The technology in the Prodigy products is far from "guesswork". Your comment is analogous to telling someone who wants to learn how to parallel park to just go buy a car that does it for you....a) you have taught that person nothing, and b) not everybody has unlimited resources to go do that.

The OEM controllers operate by a pressure sensor that responds to the hydraulic pressure in the brake system. The harder you press on the brake pedal, the more current is sent to the trailer brakes. You might want to Google that and learn.

Aftermarket controllers were available more that twenty years ago that worked the same way, but folks just wanted cheap and cheap they got.
BurbMan
Explorer II
Feb 26, 2018
Lynnmor wrote:
The day of accelerometer controlled brake controls needs to come to an end. Brakes should be controlled by the driver, not brake light switches, and the ability of the tow vehicle to decelerate... or not. Talking about milliseconds of "lead" time, is meaningless. Truck manufacturers have installed brake controllers that are far superior than the aftermarket guesswork controllers.

OK so you know you are describing how accelerometer-controlled brake controls work, right? How do you think OEM controllers work? Same as the prodigy, but that have the advantage of being engineered into factory ABS and other functions.

You may be confusing the older "timed" controls that were common before the accelerometer chip became mainstream.

Obviously you don't tow a big trailer or you wouldn't think that the lead time provided by the P2 is "meaningless".

I would agree that OEM integrated controllers are better, but they have only been available for a few years. The technology in the Prodigy products is far from "guesswork". Your comment is analogous to telling someone who wants to learn how to parallel park to just go buy a car that does it for you....a) you have taught that person nothing, and b) not everybody has unlimited resources to go do that.
Lynnmor
Explorer
Feb 25, 2018
The day of accelerometer controlled brake controls needs to come to an end. Brakes should be controlled by the driver, not brake light switches, and the ability of the tow vehicle to decelerate... or not. Talking about milliseconds of "lead" time, is meaningless. Truck manufacturers have installed brake controllers that are far superior than the aftermarket guesswork controllers.
busterbrown73
Explorer
Feb 25, 2018
4bamayoungs wrote:
Hello, folks. Been an RV'er for a little over two years, and had an experience about seven months ago that prompted me to join this forum just to get your thoughts on it. I grew up towing EVERYTHING on farms and spent a career in the military driving heavy equipment, so when it came time for a new family adventure I salivated at the thought of cruising around the country towing a small house! I needed something that would pull the TT well, but also have room for two teenagers and a set of 2 year-old twins. After much research I outfitted the crew with a 2012 Suburban with full towing package, a Tekonsha P2 brake controller, and a 32' Coachmen Freedom Express. Two years down the road and I love, love, love all three. I am pretty good at operating this size rig, but like any bonehead that has developed a level of skill I got a little over-confident on a long trip, and we set out with full water tanks a little heavier than normal. We were going to boondock at a Wal-Mart the first night, and I wanted a shower the next morning. (Stupid. Now I know.) About 20 miles down the road, I had to move left in the lane to avoid a recap in the road and it started a sway that despite all my concentration kept amplifying and within a few seconds it became obvious that I was in trouble. The sway got worse and worse until it was more like a whiplash effect and I was already starting to decide which side of the interstate I wanted to go off. Suddenly there was a loud groaning noise and the trailer snatched the Suburban back straight. The noise went away and I was driving serenely along my merry way again. After the shakes went away and I finished my thanksgiving prayers, I evaluated all the sensations I felt and it was pretty obvious that the trailer brakes had activated to stop the sway. After some limited research however, I have not been able to figure out if this was a safety feature of the brake controller or the Suburban. Can anyone shed a little light for me?

I had a similar incident on the Florida Turnpike enroute to Fort Wilderness 2 years ago. For me, it was the carcass of a blown truck tire that rolled into my lane. Without warning and at 65 mph, I instinctively swerved left as I was already in the right lane and the shredded tire was moving towards the right shoulder. This avoidance maneuver set me up for a another obstacle in the left lane, a passenger car. I corrected immediately (for obvious reasons) all the while my 35 foot travel trailer followed behind my truck as if it was riding on the same rails. Not a foot on either pedal or a hand on the brake controller. Divine intervention, maybe. Hensley Arrow, most definitely.

Sway is one of the leading factors into why RVers move away from travel trailers. With sway "elimination" hitches, trips are safer and the drive is completely relaxed. One can only really appreciate the value of a Hensley or PP if they've used one before. I say my prayers before each trip for the safety of my family and for the investment in my Hensley. Amazing engineering.
BenK
Explorer
Feb 25, 2018
You can NOT adjust the GM brake pedal light switch. It is not adjustable and is designed that way

Here is how the P2/P3 works, IIRC

Boost is the preset level that the P2/P3 will 'start' at when told to turn on the trailer brakes. Voltage level sent to the trailer harness

Mine does NOT jerk. Normally preset boost at around 2.

Smooth and can feel the trailer lead the TV in braking...until press the TV brake pedal more to get the TV to brake harder...then can feel my TV slow faster than the trailer (depends which trailer am towing)

Rarely ever need to go into more pedal pressure and the trailer and TV brakes to a stop smoothly...as one

An E-Brake will have the trailer NOT be able to brake as well, so the slop in the ball/coupler will have the ball hit the latch, but that is fractions of an inch, so I can not feel that

Once the P2/P3 is turned on, it goes to the preset boost level and then uses the accelerometer as the input as to any further increases in braking voltage sent to the trailer

Similar to using the manual lever. Manual lever goes to full voltage when the lever is all the way over to the stop. Similar but only goes to preset boost when the brake switch is turned on

Why I think that is the most likely scenario on why/how the trailer and setup corrected itself...like tossing a boat anchor out the trailer rear window...that then pulls everything into alignment.

Some times, if have presence of mind, give it a bit of throttle to pull while that boat anchor drags...gets into alignment faster

{edit}...maybe your trailer brakes are not adjusted tight enough if you have jerking while braking. Assume you have drum/shoe and if not adjusted 'tight', the attack angle will be higher...the shoes will grab more aggressively

4bamayoungs wrote:
BenK wrote:
But...if he kept his foot on the pedal all the while this was happening (maybe unconsciously...reflexively)...it could explain the why of this

All why IMHO, think is what happened during the OP's event experience

I would have to say that me moving my foot to the brake and inadvertently applying enough pressure to activate the brake light is plausible. I usually don’t set the brake controller to lead Ike that, though. The trailer brakes grabbing before the TV brakes bothers me. Could it be that I activated the brake lights and the P2 detected the momentum shift of a sway and interpreted it as deceleration?
4bamayoungs
Explorer
Feb 25, 2018
BenK wrote:
But...if he kept his foot on the pedal all the while this was happening (maybe unconsciously...reflexively)...it could explain the why of this

All why IMHO, think is what happened during the OP's event experience

I would have to say that me moving my foot to the brake and inadvertently applying enough pressure to activate the brake light is plausible. I usually don’t set the brake controller to lead Ike that, though. The trailer brakes grabbing before the TV brakes bothers me. Could it be that I activated the brake lights and the P2 detected the momentum shift of a sway and interpreted it as deceleration?
4bamayoungs
Explorer
Feb 25, 2018
BurbMan wrote:
Question: did you buy your trailer new or used? The reason I ask is that if used, the previous owner may have had an electronic sway control installed. These are motion-sensing gyro devices that will activate the trailer brakes when a sway condition is detected.

Link to Dexter Sway control

Link to Hayes Electronic Sway Control

If you felt like the trailer braes activated, they very well may have. The groaning you heard would have been weight distributing hitch straightening out suddenly in response to the trailer brakes coming on.

If you bought the rig used, the previous owner may have had one of these installed and that info wasn't passed along as part of the resale to you.

Interesting. I bought it used from a dealer. The trailer is at a storage lot, but I’ll make a trip out there and look around.

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