Vehicle Bulb Out Sensor Goes Off When Towing a Trailer with LED Lights
Question:
I have installed this kit on a shorelander jet ski trailer and the brake lights work fine went I use the turn signal they do not work I get a buld out warning on my dash but lights are on and brake lights work any sugestions on what could be wrong it is wired as per instructions I aslo have another trailer i pull and have not had a problem with it It is only this trailer
asked by: Dave P
Expert Reply:
The bulb out sensor indicates that you may have a BMW, Volkswagen, Porsche, AUdi, or other German vehicle. These vehicles have a problem when towing a trailer with LED trailer lights. The problem is what you have described. The LED lights do not draw enough power (in this case it is just the blinkers) and it makes the vehicle think there is a bulb out.
The fix is to use a special adapter, # C35FR, which will eliminate this problem because it adds load resistors that increase the draw on the system. (This will work even if you do not have a German vehicle, it is just that this problem first occurred with those vehicles.)
If your vehicle does not have a 7-Way connector and you cannot use this adapter, you will need to install load resistors on the brake/turn light wires on the trailer. You can use # DI34ZR. I have linked installation instructions for you.
If you have a 7-Way trailer connector but the trailer does not have a 4 or 5-Way flat trailer connector like the adapter requires, then there are 2 options. First, if the trailer has a 7-Way you can wait for the forthcoming 7-Way to 7-Way adapter coming out soon that works the same way as the adapter described above. Or, you can install load resistors on the trailer wiring.

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
7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs
- Trailer Wiring
- Wiring Adapters
- Multi-Function Adapter
- 7 Round - Blade
- Plug Only
- 5 Flat
- 4 Flat
- CURT
more information >
Continue Researching
- Shop: 7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs
- Shop: Trailer Wiring
- Search Results: led load resistor
- Shop: Reese Trailer Connector Adapter w/ LED Circuit Tester and Dust Cover - 7-Pole to 4-Pole or 5-Pole
- Shop: Load Resistor Kit for LED Turn Signals - 50 Watts - 6 Ohm - Qty 2
- Shop: 7-Way Trailer Adapter for Towing Trailers with LED Lights
- Q&A: LED Trailer Lights Flickering When Towed by 2015 Audi Q7
- Video: All About the Load Resistor Kit for LED Turn Signals
- Video: Curt 7-Way to 4-Way/5-Way Trailer Adapter Review
- Video: Review of Curt Wiring - Wiring Adapters - C35FR
- Shop: Curt 4-Way Flat Trailer Connector with Circuit Protected Powered Tail Light Converter
- Shop: EZ Connector Custom Vehicle Wiring Harness w/ Magnetic 7-Way Trailer Connector - Watertight Seal
- Shop: Vehicle Tow Bar Wiring
- Shop: TRED GT Wheel Chocks - Polyurethane - Green - Qty 2
- Search Results: trailer wiring
- Video: Finding the Right Trailer Wiring Harness
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Shop: Trailer Hitch
- Q&A: What is the Difference Between a 4-Way and 7-Way Trailer Connector
- Video: How to Choose a Trailer Brake Controller
- Search Results: trailer hitch
- Article: Trailer Wiring Diagrams
- Shop: Brake Controller
- Q&A: What Is An OEM Prep Package And How Do I Know If I Have It
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Search Results: trailer lights
- Video: An In-Depth Look at the Roadmaster Diode 7-Wire to 6-Wire Flexo-Coil Wiring Kit
- Search Results: brake controller
- Article: How to Measure for Trailer Hitch Drop