Tip for Solving Connection Issue Using Furrion Observation System with 2017 Mercedes GLE 400  

I have a Camplite travel trailer with LED lights. I am using the Tekonsha Prodigy RF Brake Controller and the Furrion Vision S 4.3” rear view observation system. The Furrion camera is wired to the trailer running lights. This setup was originally used with a 2012 Toyota Sequoia as a tow vehicle, and everything worked great. I use the Furrion camera system as a full time rear view mirror and really depend on it. I recently switched tow vehicles to a 2017 Mercedes GLE 400, which has the factory towing package. What I have found is that the Prodigy brake controller works perfectly, but the Furrion Vision S monitor continually goes on and off every few seconds. I thought it was an interference problem from the in car wifi, but that has been turned off. Furrion tech support recommended the Tow Ready Trailer Connector Adapter with Lamp Out Bypass from Etrailer, which I tried but had no success. The lighting and +12v connections voltage from the vehicle without the adapter were very erratic, but with the adapter they were all about 13.8 volts. Unfortunately, this did not fix the problem of the Furrion monitor screen going off and on. I tested the voltage on the running light circuit with and without the adapter, and with and without the Prodigy Brake controller in the circuit, and the voltage measured consistently around 13.6 to 13.9 volts. The voltage did fluctuate a little, but never more than a few tenths of a volt. The problem with the monitor screen cutting out continued. Next I decided to try to test wire the trailer running lights directly to the trailer on board battery. This fixed the problem, and the Furrion monitor screen does not cut out. The only thing I can conclude is that even though the voltage from the vehicle running light connection appears to hold steady, it is not, and this is what causes the monitor to behave erratically. The current to the running light circuit measured around 1.3 amps when connected directly to the trailer battery, while the charging current to the trailer battery from the tow vehicle measured about 1.8 amps, so I think I would be OK with this kind of permanent connection, and won’t discharge my trailer battery on a long trip. Mercedes says the +12v line should not be used to charge the trailer battery, but the circuit is good for 180 watts, or around 13 amps at 13.8 volts. To get the camera to work, I can wire the running lights directly to the battery via a switch or plug disconnect while towing, but I get a fault in the car telling me I have a light on the trailer out. I could wire the signal from the tow vehicle to a relay on the trailer, and have the running lights connect to the trailer battery though this relay. This would hopefully remove the fault in the car. I also think I might be able to use an LC filter circuit like they use in car audio, or a Buck Boost converter like they use in golf carts, which could smooth the voltage enough for the camera to function reliably. My preference would be a small device I could wire directly in the running light circuit. What do you recommend?

asked by: Kevin K