Problems with LED trailer lights on later cars

Known problems with LED trailer lights on later cars.
LED Lights
LED Lights are getting a lot more popular on trailers for the following reasons:-

  • They save energy meaning that you use very slightly less fuel.
  • There is no filament in an LED they last a lot longer than a bulb.
  • They do not stick out as much as a bulb light meaning they do not get broken as easily.
  • They are popular with plant and recovery companies as some will work on 12 and 24V systems meaning that bulbs do not need changing when changing tow vehicle from lorry to van or 4×4.
  • LED lights are far brighter and look much better than most bulb lights

We do find compatibility problems with LED trailer lights and high-end vehicles since 2000 fitted with ‘plug-in’ wiring kits.
Vehicles fitted with aftermarket towbars usually are not fitted with these plug-in systems. Towbar fitters are usually trying to do the job as cheap as possible and use a bypass system instead as this is a lot cheaper. With all bypass relays fitted on cars the lights work as they should but LED lights do not draw enough power for the indicator buzzer to work on most of these relays.
There are 2 problems that plug-in systems can give. Some systems send test pulses to check that the vehicle lights are functional, this is what causes LED lights to flash. Other systems are not activated until a load is detected. The problem here is LED’s are so sensitive they don’t have sufficient load to trigger the sensors on the plug-in system. Therefore they are not detected, and as a result no lights work.
The vehicles that we have seen the problems on are as follows.
Mercedes. Most models from 2000 both problems dependant on the kit fitted.
BMW. Flashing LED lights on most models but some can be cured by introducing a load, others need bypassing.
Discovery 3. Flashing on indicators only.
Range Rover and Range Rover Sport. Flashing indicators only.
Iveco Trucks. All lights flashing.
We have had various other reports but we have only experienced the list above for ourselves.
Towing and Trailers Ltd will plug an LED Lightboard into your car at their premises to test your vehicle free of charge before you buy LED lights.

If you are looking to buy trailer lights, choose from a large selection at Trailer Lights