Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-20-2020, 09:56 PM   #1
1 Rivet Member
 
Kirkland , Washington
Join Date: May 2020
Posts: 12
Question Brake controller for 2014 MB ML350

I am a complete noob of towing a trailer, so please bear with me . In a separate post I made earlier today, I learnt even with factory installed tow package for my car, I still need a brake controller. So I did some research and end up even more confused. Hope someone can help me understand how things work together.

From what I read, a proportional brake controller is the way to go. But what puzzles me is that they are activated by deceleration detection, thus they have to be installed in certain angle. But why use deceleration? When I step on the TV brake, isn't the TV brake system supposed to send proportional signal to the brake controller? If TV's brake system doesn't do this, why would they have a 'hatch' with plug right above the brake in cabin to hook up to the controller? Is that just to run the wire all to the 7-wire plug under the rear bumper of my car? Am I missing something?

My original understanding of how the tow package works was this
1. TV driver step on the brake, this slow down the TV, at the same time a proportional electronic signal is send through the wire to the 7-wire connector under the rear bumper.
2. Trailer has the 7-wire plug/cable plugged into that connector, so the brake signal reaches electric brake system on the trailer, and the brake system uses on board battery power to drive the brake to engage thus slow down the trailer.

But from what I read, it seems like this is how it works:
1. TV driver step on the brake, the TV decelerates and this is detected by the trailer brake controller and it sends the signal to the wire.
2. The signal is "amp'd" with TV's battery power to a higher voltage current to the 7-wire connector.
3. This higher voltage current goes to the trailer's brake system and directly drives the brake to engage, and slow down the trailer.

I can understand that the TV needs to be designed to power brake on different kind of trailers (many non-RV trailer does not have on-board battery to drive the brake, like a cattle trailer), but the deceleration based activation makes it like there is no integration with TV at all.

I am really confused right now, I'd really appreciate it if anyone can educate me on this. Thanks much!
__________________

hovr is offline   Reply With Quote
Old 05-21-2020, 06:11 AM   #2
Rivet Master
 
2018 25' International
Slidell , Louisiana
Join Date: Sep 2017
Posts: 827
hovr, again welcome to the forum. These are actually great questions. I bet most people have no clue what going on with their trailer brakes.

Without a brake controller the tow vehicle has no logic built into its braking system to generate a signal proportional to stopping force. There is no instrument to sense the force applied to the brake petal or hydraulic pressure, or any other proxy for stopping force. So with a seven wire factory harness you are brake controller ready, but the brake wire has nothing appropriate to connect to. As far as I know, no modern vehicles have the wire energized with no controller. Back in the day the early controllers were simply a variable resistor/voltage controller that sent a constant voltage signal that the driver could adjust. No mater how much braking force was applied on the tow vehicle, the trailer would always get the same braking force.

Modern controllers have an accelerometer in the controller to sense braking force as you learned. Turns out the better profile for electric brakes is to make it proportional to deceleration. It provides a variable braking force that is reasonably matched to vehicle behavior. It is also inexpensive and easy to install, since you don't have to tap into the suspension computer or add a new sensor. Some factory controllers are a bit more sophisticated and use more of the available data from the vehicle computers including the engine and transmission and traction/handling but many don't.

Why bother running the control wire all the way back to the driver? This is so the controller can be "tuned" by the driver to have the right "gain" or amplification and so it can be manually activated for emergencies and for testing. Some modern controllers are attached at the trailer hitch and use a wireless signal for the driver. I'm not sure how I feel about that when a wire is easily available. I guess wires can fail too.....

You are correct the aftermarket controllers have no direct integration to the tow vehicle, but consider that the ultimate measure of brake function in a vehicle is two dimensional acceleration anyway. Any other signal the vehicle could provide to the controller is secondary given the current simple design of trailer brakes.

Hope this helps.
__________________

__________________
Brian
BayouBiker is offline   Reply With Quote
Old 05-21-2020, 09:02 AM   #3
Rivet Master
 
Mollysdad's Avatar
 
2017 26' Flying Cloud
Tampa , Florida
Join Date: Feb 2017
Posts: 4,428
Blog Entries: 1
Tekonsha P-3 controller can be mounted at any angle. The accelerometers 'know' which way is up. I got a surprise once when I moved mine while braking. Whoa!
I'm not sure if the MB has LED taillights which may need a more complex unit than the plug and play.
Tekonsha now makes a wireless version for this application.
Mollysdad is offline   Reply With Quote
Old 05-21-2020, 09:14 AM   #4
Rivet Master
 
waninae39's Avatar

 
2017 22' Sport
NCR , Ontario
Join Date: Feb 2017
Posts: 1,902
We use the Tekonsha P-3 controller in our Audi Q5
it works very well once setup.

best to go to a high quality dealer and have them set it up while you are in the TV
they will show you what they did and why

Ours it setup so that the AS breaks just start to lock under heavy breaking and then we dial it back one step.
That way we get maximum braking force in the AS and all 6 wheels break equally
waninae39 is offline   Reply With Quote
Old 05-21-2020, 09:18 AM   #5
Rivet Master
 
gator.bigfoot's Avatar
 
2007 30' Classic
KW , Ontario
Join Date: May 2012
Posts: 552
There should be a factory connector under the dash. You should be able to plug your P3 directly into it. That is the way mine is hooked up on my 08. I had MB install the first one and I installed the P3 myself when I bought the AS.
gator.bigfoot is offline   Reply With Quote
Old 05-21-2020, 09:46 AM   #6
1 Rivet Member
 
Kirkland , Washington
Join Date: May 2020
Posts: 12
Yes, I have located the cable, which has a very odd plug, from some MB online forum people order it from MB for $24 :O. I found for $150 I can get the CURT spectrum which is similar to the P3, but the main unit can be tucked away from the button/knob.

Thank you for sharing your experience!
hovr is offline   Reply With Quote
Old 05-21-2020, 09:52 AM   #7
1 Rivet Member
 
Kirkland , Washington
Join Date: May 2020
Posts: 12
Thank you again Brian!

I thought the proportional signal can be derived from brake pedal travel distance? I believe many(if not most) cars made in last 10 years has this kind of circuit.

Quote:
Originally Posted by BayouBiker View Post
There is no instrument to sense the force applied to the brake petal or hydraulic pressure, or any other proxy for stopping force.
hovr is offline   Reply With Quote
Old 05-21-2020, 10:09 AM   #8
Rivet Master
 
2018 25' International
Slidell , Louisiana
Join Date: Sep 2017
Posts: 827
You may be correct, I'm not aware of that style.

I have an integrated controller on my 2013 Ram 2500. It uses speed, acceleration, engine/exhaust brake horsepower, transmission gear and torque, traction and some additional user settings including a gain to generate its output. I can't speak about the effectiveness of aftermarket systems so I'll let others address that.
__________________
Brian
BayouBiker is offline   Reply With Quote
Old 05-22-2020, 11:12 AM   #9
1 Rivet Member
 
2010 25' FB Flying Cloud
Waterford , New York
Join Date: Jan 2016
Posts: 8
I also have a 2014 ML350 Bluetec. I purchase my Tekonsha P-3 controller from etrailer with the correct male / female plug / lead pre wired from them for my MB. Went to my local MB dealer and they dropped the brake controller lead from under the dash for me and secured it to the side wall just below the dash. Drilled a couple of tiny pilot holes and mounted the Tekonsha P-3 controller to the underside of the dash. What a difference! Hope this helps
HoverLover is offline   Reply With Quote
Old 05-22-2020, 12:05 PM   #10
Rivet Master
 
Mollysdad's Avatar
 
2017 26' Flying Cloud
Tampa , Florida
Join Date: Feb 2017
Posts: 4,428
Blog Entries: 1
Quote:
Originally Posted by HoverLover View Post
I also have a 2014 ML350 Bluetec. I purchase my Tekonsha P-3 controller from etrailer with the correct male / female plug / lead pre wired from them for my MB.
The Tekonsha website has a vehicle finder so it can tell you what you need. The hardest part of installation was finding the pigtail, and there's YouTube videos for most.

I just went to the site and it says you need a 3066-P cable to plug and play.

Mollysdad is offline   Reply With Quote
Old 05-22-2020, 12:59 PM   #11
1 Rivet Member
 
Kirkland , Washington
Join Date: May 2020
Posts: 12
Thank you so much! this is exactly what I need.

Does it need to be mounted at a place you can see and operate it while driving? or you just need to calibrate it - set it and forget it?

If I need to see and operate it while driving, then one place I can think of is right under the parking brake pull/push button on left side, but that's a place I'd hesitate to drill and screw - no idea what's behind it. If it's set it and forget it I can mount it further down on to the soft plastic piece that can be easily take off by unscrew a few screws.

Thanks again!
hovr is offline   Reply With Quote
Old 05-22-2020, 01:06 PM   #12
1 Rivet Member
 
Kirkland , Washington
Join Date: May 2020
Posts: 12
Thanks, @HoverLover. I have located the wire right next to the diagnostic plug, right next to the red hood release pull. Did you drill pilot holes on the 'leatherish' textured plastic or the crappier plastic further down under the dash? I am a little hesitate to drill on the textured surface as I don't know what's behind them - would be bad if I drill into some wires.
hovr is offline   Reply With Quote
Old 05-22-2020, 01:19 PM   #13
Rivet Master
 
2018 25' International
Slidell , Louisiana
Join Date: Sep 2017
Posts: 827
You should have access to the lever/control that allows manual actuation. Applying trailer brakes only controls sway if that were to occur and allows you to test the system each time you hit the road.
__________________
Brian
BayouBiker is offline   Reply With Quote
Old 05-23-2020, 06:06 AM   #14
Rivet Master
 
gator.bigfoot's Avatar
 
2007 30' Classic
KW , Ontario
Join Date: May 2012
Posts: 552
Quote:
Originally Posted by BayouBiker View Post
You should have access to the lever/control that allows manual actuation. Applying trailer brakes only controls sway if that were to occur and allows you to test the system each time you hit the road.
Unfortunately that means you mount the unit where you can reach it. I have mine below the steering wheel. You also want to be able to see what the unit is doing. One annoying thing about MB is that when you drive with the cruise control on, is that going downhill means the car brakes automatically. This is really annoying when hooked up to a trailer. Just kills your fuel economy. So when I see that it is braking I turn off the cruise.

I think the editor of AS magazine had a GL and he had his mounted on the top of the dash. Not sure I'd like that, but to each their own. There may be better ways to mount it without damaging the look or the dash and maybe even removing it when it isn't used.
gator.bigfoot is offline   Reply With Quote
Old 05-23-2020, 11:02 AM   #15
1 Rivet Member
 
Kirkland , Washington
Join Date: May 2020
Posts: 12
Ah, that's a good point, so definitely not at where I cannot see while driving.
hovr is offline   Reply With Quote
Old 05-23-2020, 04:11 PM   #16
"Space A" S/O Registry 11
 
2006 34' Classic S/O
Fort Worth , Texas
Join Date: Feb 2007
Posts: 1,050
DirecLink, by Tuson is the latest technology. It derives the TT brake information from the TV's OBDII socket under the dash. It reads any brake action the TV experiences. Airstream started selling them some time ago. Direct link also sells an anti skid option for the TT, but the Direclink picks up the TV's brake cycling prior to skidding anyway.
guskmg
guskmg is offline   Reply With Quote
Old 05-23-2020, 07:58 PM   #17
3 Rivet Member
 
2019 22' Sport
Carlsbad , California
Join Date: Nov 2018
Posts: 177
Look into the Curt Echo. Simplest solution out there, works great
Prettygood is offline   Reply With Quote
Old Yesterday, 05:58 PM   #18
1 Rivet Member
 
2010 25' FB Flying Cloud
Waterford , New York
Join Date: Jan 2016
Posts: 8
Tekonsha P-3 Mount

This is my mount for the Tekonsha P-3 controller. I used 3M mounting hook tape to back it up, "BUMP" proof for my bride who constantly forgets it's there. No worries about the screws, my MB tech assured me there was nothing behind that location.
Good luck and happy trails.

BTW are you a Helicopter Pilot?
Attached Thumbnails
Click image for larger version

Name:	Mount.jpg
Views:	3
Size:	400.8 KB
ID:	368647  
__________________

HoverLover is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
2014 Mercedes ML350 Diesel cjlever Airstream Classifieds 0 12-20-2018 09:25 AM
2014 ML350 BlueTec w/CanAm Hitch Reinforcement 2012FB Airstream Classifieds 0 06-15-2015 05:22 PM
2014 ML350 - AS FC19 Tow Combo drftboat Towing, Tow Vehicles & Hitches 7 12-14-2014 08:49 AM
2014 ml350 2012FB Towing, Tow Vehicles & Hitches 8 03-10-2014 07:36 PM
New F150 '09 brake controller vs. Prodigy brake controller dukester Brakes & Brake Controllers 17 01-20-2009 10:46 PM


Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.



All times are GMT -6. The time now is 02:27 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.