Mercedes-Benz Forum banner

1 - 18 of 18 Posts

·
Registered
2001 E320; 2002 ML500
Joined
·
1,982 Posts
Discussion Starter #1
Folks,
I'm purchasing a travel trailer with electric brakes which requires a brake controller and a 7 pin round connector.
My vehicle has a 4 pin connector that I installed adding a Modulite type electronic device.
When I had my '99 ML430, it came from the dealer with a hitch and a 7 pin connector. My questions are:
1) Was the 7 pin connector in my ML430 ready for towing a camper with electric brakes without the addition of a brake controller?
2) If yes, I never saw a brake controller installed in that vehicle; could the AAM have provided that function?
3) The connector at the left rear compartment in my ML500 has several other pins that were not used when installing the MODULITE adapter. Could those be directly wired to the 7 pin connector or must I wire them to a brake controller?
4) Pardon my ignorance here since I've never had a camper before, where do the camper's electric brakes get power from? The trailer's battery or directly from the vehicle? I would think from the vehicle since a dead trailer battery would imply no brakes...

I need to make sure I do this right as the camper can weigh as much as 4,500 lbs and I don't want all that weight to be stopped by the vehicle's brakes.

Thanks!
 

·
Registered
1999 ML320
Joined
·
352 Posts
Brake questions

1. You need a brake controller in order to use your trailer's brakes.

I don't know if your existing wiring will facilitate the 7 pin connector.

I strongly recommend looking at a weight distribution hitch and system for your SUV and trailer. The ML has a relatively short wheel base and there might also be issues with the tongue weight of the trailer. The weight distribution system takes weight off the hitch and distributes it making your SUV much more stable. It also makes your vehicle squat less in the rear.

My 2 cents.

(I used to tow a lot with my ML until I purchased a pickup to do the tough work)
 

·
Registered
2001 E320; 2002 ML500
Joined
·
1,982 Posts
Discussion Starter #3
Thanks bayenda.
Do you recommend any particular make/model weight distribution system? Would that require a completely different hitch or an adapter that connects to the existing one?
 

·
Registered
1990 190E 2.6,.... 1998 ML320, 2005 ML500SE
Joined
·
3,103 Posts
Folks,
I'm purchasing a travel trailer with electric brakes which requires a brake controller and a 7 pin round connector.
My vehicle has a 4 pin connector that I installed adding a Modulite type electronic device.
When I had my '99 ML430, it came from the dealer with a hitch and a 7 pin connector. My questions are:
1) Was the 7 pin connector in my ML430 ready for towing a camper with electric brakes without the addition of a brake controller?
2) If yes, I never saw a brake controller installed in that vehicle; could the AAM have provided that function?
3) The connector at the left rear compartment in my ML500 has several other pins that were not used when installing the MODULITE adapter. Could those be directly wired to the 7 pin connector or must I wire them to a brake controller?
4) Pardon my ignorance here since I've never had a camper before, where do the camper's electric brakes get power from? The trailer's battery or directly from the vehicle? I would think from the vehicle since a dead trailer battery would imply no brakes...

I need to make sure I do this right as the camper can weigh as much as 4,500 lbs and I don't want all that weight to be stopped by the vehicle's brakes.

Thanks!
1) NO.
2) ML trailer hitch did not come with a brake controller.
3) NO. there was no pre-wiring for a brake controller.
4) All the brake controllers that I have seen use vehicle battery power.

The multi pin round connector that came with the ML's trailer hitch kit did have provisions for the extra pin for the brake controller wiring but you must wire it yourself.

You may want to visit a trailer specialist like U-Haul for advice on installing brake controllers.
Mike
 

·
Registered
2001 E320; 2002 ML500
Joined
·
1,982 Posts
Discussion Starter #5
Got it Mike.
Thanks.
I'm thinking of wiring a +12V long 10 AWG wire from the passenger's footwell fuse box directly to the rear of the truck and then wiring the brake controller using that +12V wire to supply power to it.
 

·
Registered
1999 ML320
Joined
·
352 Posts
Weight distribution

This is a link to a pretty explanation of weight distribution systems
Common Weight Distribution and Sway Control Questions | etrailer.com

I have the Reese version. The weight distribution system incorporates 3 key pieces.
1. A special Shank with a standard ball (which fits into a standard 2" hitch)
2. 2 bars which go between the new shank and the trailer.
3. Attachment to your trailer. For me, I could not use the standard attachment and had to screw the attachments directly to the trailer.

The key part about buying a weight distribution system is the tongue weight of the trailer and the trailer weight. Only after you have that information can you make an informed decision. You can also get sway control attachments to the weight distribution system but my trailer didn't need it.

This system is very easy to install and the more practice you get, the faster each hookup is. It took me no more than 3-4 minutes to hook mine up each time.

You will feel much safer driving with one. If you lived closer, I would let you borrow mine.
 

·
Registered
2001 E320; 2002 ML500
Joined
·
1,982 Posts
Discussion Starter #7
Thanks bavenda. I definitively want a weight distribution system AND anti-sway since I want the highest possible level of safety. My concern was with having to replace my existing hitch but from what I gather that is not the case.
 

·
Registered
2001 ML430 Sport bought in very nice shape despite 156K miles in August 2010
Joined
·
540 Posts
You definitely need the weight distribution/anti-sway for this application. 4500# is quite a large load for the ML, and its short wheelbase is marginal for this application. You need everything set up carefully to minimise risk of the tail wagging the dog.

Take a look at the Tekonsha Prodigy brake controller.
Its one of the best, and widely used by us guys who tow race car rigs. None of htese controllers are internally fused, so if you are picking up power from the cabin fusebox you MUST install an in-line fuse. Best bet is to use an in-line circuit breaker. These are self-resetting devices which recover after an overload.
 

·
Registered
2001 E320; 2002 ML500
Joined
·
1,982 Posts
Discussion Starter #11
Thanks APKhaos,
The empty weight of the trailer is 3850 lbs but the GVW is 4500 lbs (water, etc). Hope this doesn't put too much strain on the V8 ML.
The Prodigy unit you mention is exactly the one I was looking at earlier. Will use an in-line circuit breaker as well.
 

·
Registered
1999 ML320
Joined
·
453 Posts
Sergio,
I bought my OEM Oris hitch and installed it with the original wiring. I believe my harness came with black electric brake controller box as part of the harness. you can contact Oris company direct Philip Wiltshire [[email protected]] for more informations.
All of them for W163 were made in Germany, for US labeled 500 lbs. tongue weight and 5000 lbs. capacity, for Europe 650 lbs. and 6500 lbs. capacity.
I believe that you don't have to pull any wires to the back of your ML because there is fused wire there for your aftermarket controller. I have the buletin with schematic for controller connection at home in my Mercedes folder, with all wire connections by their color. I think I found it on Aldata.
I can scan it and post it on monday, you can send me PM so I don't forget.
I seen few oem hitches with harnesses on e-bay but non of them had the black box on them that originally came with mine. Sorry if I'm wrong but I have the installation instructions and I will check it out for you.
I haul home Dodge Intrepids 4572 lbs. plus 1300 lbs. dual axle aluminum rental trailer, from as far as Detroid and Indianapolis and never had any problem so far and my Ml has the smaller standard brake set, not the big Brembo double piston equipment on 430 and 500 trucks.
Bernard
 

·
Registered
2001 ML430 Sport bought in very nice shape despite 156K miles in August 2010
Joined
·
540 Posts
I believe my harness came with black electric brake controller box as part of the harness.
Maybe that black box was the light driver for the trailer lights? Most trailer harnesses include an isolator/driver to completely separate the power to the trailer lights from the truck light circuits. It senses the truck light circuit, and drives the appropriate trailer light from 12V truck power. Its highly unlikely that a box that ia part of the harness was a brake controller.
 

·
Registered
2001 E320; 2002 ML500
Joined
·
1,982 Posts
Discussion Starter #15
Thanks for all the replies. Bernard, do you have a tranny cooler? Is one required or recommended for such heavy loads?
Please post the diagrams. I will send you a PM to remind you.
Thanks again.
 

·
Registered
2015 ML 63
Joined
·
95 Posts
Thanks for all the replies. Bernard, do you have a tranny cooler? Is one required or recommended for such heavy loads?
I learned these ML's are GREATLY under-rated in the US. After an online poster informed me of the fact I checked with my Local Mercedes Dealer who verified that the actual rating is 7200 lbs as are all of the newer models. Two summers back I purchased a 25' 6300 lb boat on a 1000 lb trailer. Had my 02, ML55 serviced with all fluids changed, including the Brake Fluid, took a 600 mile trip up to Destin Fl and towed the rig back cruising 65mph all the way in mostly 85-90 degree weather. No Problem. I later learned the Surge Brakes on the trailer were in bad shape due to the fluid being loaded with water. I give a lot of the credit of not having any stopping issues to the brake fluid change before the trip as I immediately noticed a huge improvement upon leaving the dealership.
 

Attachments

·
Registered
1999 ML320
Joined
·
453 Posts
Here is the model 163 brake controller installation buletin.
Maybe I am wrong and the black box is just a power insulator for trailer but I didn't see it on other harnesses. In my installation guide they call it #21 Turn signal indicator and brake module.
Bernard
 

Attachments

·
Registered
2001 E320; 2002 ML500
Joined
·
1,982 Posts
Discussion Starter #18
Thanks Bernard. That is very helpful info.
 
1 - 18 of 18 Posts
Top