Manual handheld controller for trailer lights?
 

For our 2011 mercedes ml350 the hitch and wiring harness installed is upwards of $3500, and all we need to do is tow the boat a few miles twice a year, so it really isn't worth it. Found an aftermarket hitch for cheap, but the wiring harness... Is there some sort of handheld controller you can buy where you can manually turn on the turn signals? Or anything similar

I don't know about commercially available solutions but for turn signals and running lights it would be pretty easy to make a little box with switches that plugs into the 12 volt accessory outlet to control and power it all. Make a long extension to plug it into the trailer and keep the box by the driver. The only complex part would be the brakes. You obviously can't rely on a manually activated brake light switch. You'd either need to add a secondary switch to the brake pedal or some sort of inertia switch that detects deceleration and activates the lights. You probably could tap the existing brake pedal switch without issue and use a 2 pin sae plug to connect/disconnect your box when not in use. Have the pedal switch activate a relay that powers the brake lights.

This guy reported success with a $60 Reese converter box on a 2012 ML350:
http://mbworld.org/forums/new-m-clas...ch-wiring.html

Why don't you just buy a pigtail harness and splice it into the rear light harness?

Would that work? Just splicing a pigtail and connecting to light harness? If so then what is the point of a wiring harness setup?

I'm not sure what kind of boat you have, but on my2003 SAN, the brakes lock up in reverse if the reverse light is not on when backing up/

I don't think splicing in the pigtails works on the newer circuits... Most new cars and trucks have separate circuits and fuses for trailer lights.. If you add the load of the trailer lights to your vehicle light circuit, it'll probably blow a fuse and the light monitoring systems sense bulb resistance..

Ron just apply 12 volts to the blue wire to release the brake solenoid..

I'm thinking making a homemade box with a few switches and just a seperate 12v battery maybe from an ATV or something similar will be the best bet. Or just having someone follow close behing the boat so no cops see....

Rent a truck twice per year. You could make a box if you really wanted to.

I agree with someone above. This kind of thing would work for you...http://www.reeseprod.com/products/el...GqzpQVXzg!SbA=

Definitely go for a module like this with 5 pin wiring rather than the 4 pin module recommended on the Mercedes forum that I referenced above. Most boat trailers will have surge brakes with a reversing solenoid. You'll need that 5th pin. Wiring should be the same as on that Mercedes forum post linked above but you'll have one more wire to connect wherever you can tap a reverse light circuit.

I think it's the way to go. You'll spend more time making a stand alone box than installing one of those adapter modules. They supposedly draw less than 5 ma from the lighting circuits so any fancy pants bulb monitoring systems shouldn't even know it's there.

Flame shield on...

A few miles a couple times per year? Seriously just power the trailer tail lights from the boat or a small battery pack and don't quick stops or make any erratic turns.

I'm cool with this but do so at your own risk obviously. Get a female (vehicle side) 5 pin connector:
https://www.amazon.com/dp/B005XWNCHS/

A 2 pin flasher:
http://www.amazon.com/dp/B000GKAZCW/

A couple of crimp on female quick connects, 2 alligator clips, a fuse holder with maybe a 5 amp fuse, and a pair of wires of sufficient gauge and length to go from your boat's battery to the trailer light connector.

Extend the white wire to an alligator clip that can connect to the negative on your boat battery. Twist the yellow and green wires together and extend a single wire from those to within 1 ft of the battery. Connect the flasher inline there followed by your fuse holder then the alligator clip for connection to the + side of the battery.

Plug this in and it should start flashing the hazards on your trailer. Shouldn't take but 15 mins or so to make.

Is it illegal to drive with only the hazards on? Don't you need to properly signal turns and stops?

It's probably not legal but for a few miles twice a year I doubt you'd have an issue. I see people towing regularly with absolutely no trailer lights and just the vehicle's hazard lights on. You'd be better than that. You'd probably not be legal with a manually activated brake light switch anyway.

I think hand signals are still acceptable in most states in lieu of illuminated turn signals.

I am pretty sure what you are proposing is illegal, so who gives a crap.

How about this, screw inspection, register the trailer and don't plug the lights in. That way if you do get pulled over you don't have some jack-sht wired piece of crap to explain "uhhh I was too cheap to get a wiring harness" - too cheap, the law doesn't care, you are driving around in a vehicle and boat worth $150k in the officers eyes.

You just say "Vehicle doesn't have harness, trailer isn't inspected", take your licks and walk away. Have a shadow vehicle and you'll be fine for a few miles.

Does anyone know where I could get an aftermarket hitch? Found a few for our 2011 merc 4matic but they only have a 3500# capacity. The car is rated for 7200# and the boat and trailer will be close to 6000# (malibuu 247) so I definitely need a hitch rated greater.

Have you tried Curt hitches

Aftermarket it looks like there are 5000lb hitches for the 2012 but only 3500 for the 2011.

The factory installed equipment gives you a higher rating but at big cost.

Either way it sounds like the best might be:

Looks like ill be renting another uhaul this year