Fuse for trailer lights - 2012 Mercedes-Benz M-Class ML350 BlueTEC 4dr SUV 3.0L V6 Turbodiesel AWD 7-speed Automatic

The location of the fuse for the running lights on a trailer may vary depending on the make and model of your vehicle. However, here are some general steps to help you locate the fuse:

1. Check your vehicle's owner's manual to determine the location of the fuse box. The manual should also provide a diagram of the fuse box and a list of fuses and their functions.
2. Once you have located the fuse box, open it and look for the fuse labeled "Trailer" or "Trailer Lights." Some vehicles may have a separate fuse box specifically for trailer wiring.
3. If you cannot find a fuse labeled for the trailer lights, check the fuses labeled "Parking Lights" or "Tail Lights." These fuses may also control the trailer's running lights.
4. If you are unable to find the correct fuse, you may need to consult a mechanic or the dealership for assistance.

Remember to always replace a blown fuse with one of the same amperage rating. If the new fuse blows immediately after installation, there may be a wiring issue with the trailer or vehicle that needs to be addressed.

trailer lights are fused in the main fuse box of the car
tail lights on a trailer are the same fuse for tail lights of the car , the same for brake lights and indicators

there is no special fuse for a trailer as the trailer lights are just an extension of the car lights , so if the lights do not work on the trailer but do on the car the problem is in the connections
if the car lights do not work then check the tail light and brake light fuses in the car after you fix the shirt in the trailer connections

The trailer lights on your van should be fused independently of the vehicle lights if you have the factory wiring. There is a fuse junction block under the hood [should be in the left corner somewhere] and in that you should find the fuses for the trailer lights and other functions. This is from memory but check fuses #5 and #6, [10 amps fuses] and see if they are blown. I could be wrong on the numbers so you might have to check them all. Usually its the trailer that causes these fuses to blow so if you find a blown fuse replace it and make sure it doesn't blow again by testing all the lights with the trailer unhooked. If that's ok then hook up the trailer and check again. If it blows with the trailer hooked up then you probably have a short circuit in the trailer wiring somewhere. Good luck, hope this helps!

Not sure which fuse you checked.
The Engine Compartment Fuse Panel ( Battery Junction Box / BJB ) is where the fuse is for the trailer tow adapter parking lamps.
Fuse # 5 is the fuse for the parking lamps, and the reversing lamps.

Next is the trailer tow adapter park lamp relay. This is what BJB Fuse #5 feeds, and the coil is operated by the truck's parking lamps. This is also in the BJB, Relay 201, it is the 1/2 size relay.

Not sure what you took a resistance reading from on the trailer tow adapter.

If you want, you can pull the trailer tow park lamp relay, and jumper the normally open contacts, which should provide power at the trailer tow adapters, regardless of the truck's lights.


This is the wiring diagram for the trailer tow park lamps

most trailers don't have fuses, but rely on the car fuses, and if the car lights go on, that can't be it.
You need a test light.
Check if the current is getting to the trailer connection, then check at the trailer bulbs.
But the ground connection is the most likely if none work.
The trailer itself is the ground for the lights, but you need a brown wire from the trailer frame to car frame/ground.

its in the engine compartment in the fuse box on the drivers side next to battery

Also try http://www.etrailer.com/faq-wiring.aspx. They have a great website with lots of info.

yes there is , under the hood in a fuse block on left side of engine compartment , will be a 10 amp trailer parking lamps fuse ( TRL PARK ),,, also on right side of dash will be a right trailer turn/stop fuse and a left trailer turn/stop fuse, just for your information . i don't know if it will be plainly identified , if not maybe your owners manual can help identify it . were rootin for ya .

J5

You will need to get a 12 volt test light and check the trailer connector for a voltage signal to the trailer, it may also have seperate fuses under the hood for the trailer lights if the system is factory installed, federal law requires the 2 systems be isolated, if there are blown fuses find the short in the trailer before replacing fuse(s), with no exceptions the short is always in the trailer. Hint, check the fuses 1st.