Trailer Running Lights Do Not Work When Connected to 2014 Mercedes ML 350 BlueTec
Question:
Hi, I have a Prodigy RF brake system installed on my Mercedes 350 ML Bluetec. I used the adapter 20142 with Lamp out sensor bypass to pair the brakes. All parts purchased from ETrailer. The pairing of the brakes worked perfectly. However, I cannot get the tail/running lights to work. They flash intermittently but will not light up when the lights are activated. The brake lights and turn signal lights work fine. I have checked the pins and they seem to be aligned properly. Any suggestions on what I can to do get the running lights to work?
asked by: Ross P
Expert Reply:
It sounds like there is either a ground problem on the trailer or adapter # 20142 is not offering enough resistance to power the lights properly.
Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light.
Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.
The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.
If the grounds are all fine then the likely cause is not enough resistance from the lights. You would only need to install one load resistor on the running light circuit (or two if the running light circuit is split at the trailer connector) to solve this problem. For a pair use # DI34ZR.
Products Referenced in This Question
Load Resistor Kit for LED Turn Signals - 50 Watts - 6 Ohm - Qty 2
- Accessories and Parts
- Trailer Lights
- Load-Resistor Kit
- Diamond
more information >
Product Page this Question was Asked From
Trailer Connector Adapter w/ Lamp-Out Sensor Bypass - 7-Way RV to 7-Way RV - Vehicle End
- Trailer Wiring
- Wiring Adapters
- Single-Function Adapter
- 7 Round - Blade
- Plug Only
- 7 Round - Blade
- Tow Ready
more information >
Continue Researching
- Article: Determining Trailer Tongue Weight
- Q&A: Tool for Adjusting Drum Brakes on Drop Axle
- Q&A: Curt Triflex Brake Controller Displays 05 and Trailer Brakes Not Working with Brake Pedal
- Article: Testing Trailer Brake Magnets for Proper Function
- Article: Trailer Wiring Diagrams
- Article: How to Choose the Right Trailer Hitch Class
- Article: What is the Best Trailer or RV Storage Cover
- Q&A: Heavy Duty Trailer Hitch Receivers For 1989 Chevrolet C/K Crew Cab Pickup
- Q&A: 10K Torsion Axle Compatibility With Disc Brakes
- Q&A: Installing Tekonsha Prodigy P3 In A 2022 Toyota Highlander XLE Without Factory Tow Package
- Q&A: Complete Flat Tow Parts For 2024 Chevy Silverado 1500 4x4
- Q&A: Amount of Play on Dexter 12K Torflex Axle Under Max Load
- Article: Trailer Tire Sizing
- Article: 5 Things to Know About Weight Distribution Hitches