My car is displaying warnings when I tow my caravan

My car is displaying warnings when I tow my caravan

NOTE: If you have a Swift caravan that is fitted with LED road lights, depending on your tow vehicles compatibility, warnings can be displayed in your vehicle and some lights may not function correctly.

Why does this happen?

Vehicle manufacturers have a requirement to monitor the directional indicators and a warning will be displayed to inform the driver if the directional indicators fail.

The reason the warnings are displayed when the caravan has LED road lights is, traditionally the road lights would be a 21W lamp drawing 1.75A and now the LED’s might only be 2W or 3W drawing around 0.25A. This means that when the vehicle is monitoring and looking for a load of 1.75A it doesn’t detect the 0.25A load from the LED and the warning would be displayed.

Not all towing vehicles would display an issue though because the vehicle manufacturers do not have to monitor to a set of parameters or standards, meaning some vehicle manufacturers monitoring parameters might have a range that went down to 0.25A so the vehicle would be happy that the light is there and operating so no warnings would be displayed. Other manufacturers parameters might have a range that only went down to 1A so the 0.25A load from the LED wouldn’t be detected and the warnings would be displayed.

The Solution

We have developed a range of LED road light electronic control units (VLM units) that make the LED road lights fitted on a Swift caravan compatible with most towing vehicles and can easily be integrated into the existing wiring installed in your caravan.

These units work by adding resistors into the road light circuits that then increases the load to a level that is within range of the towing vehicles monitoring parameters. They then monitor the LED road lights at their lower running current and if the LED’s fail the VLM takes the resistor out of circuit, the towing vehicle would then display a warning and still meet the requirement to monitor the directional lights.

VLM4 Unit - now no longer manufactured 

We originally produced a number of VLM4 units, which differed by vehicle manufacturer, with a choice of 7 units.  These units have now been replaced by one newer VLM6 unit, and the VLM4 units are no longer manufactured.
For reference, this is what a VLM4 looked like.
 

VLM6 Unit

The unit is directly compatible with 2019 model year caravans and 2018 model years caravans fitted with the larger format C44+ fuse box, which was introduced in October 2017.  The unit can also be fitted to 2016 and 2017 model year caravans (which originally would have used the now obsolete VLM4) with a little extra installation effort by following the guidance in the VLM6 specific information linked further below.
  

Advantages of the VLM6

The VLM6 is designed to be one size fits all, so unlike the older VLM4 with 7 different versions the VLM6 only has one version, and although we can’t guarantee it will work with every towing vehicle it should work with most.

The benefit of this is if you have more than one towing vehicle both will be compatible and if you sell and replace your towing vehicle with something new that should be compatible as well.
Please click the link to our web site if you would like to purchase: Sargent Web Shop - VLM6 (LED road light electronic control unit - Caravan)
Further information on the VLM6 can be found here VLM6 (LED road light electronic control unit - Caravan)