when the caravan is connected to the car and i engage reverse gear the sensors go off.the car is a 2007 l+k sould this be happening.and what to do to stop this.

has the ecu been told you have a tow bar?

 

It should be set so the car knows when the towbar electrics are being used the rear sensors are turned off

Does this only work with the dedicated wiring kit?

If you wire it up with a multi bypass relay the ecu does not know.

The electrics on mine is on a bypass relay. Have yet to tow with it to find out.

If you have aftermarket towbar wiring you could use a fog light cut off relay only wire it to the buzzer for sensors instead.