Hello,As far as i know there is no way of knowing for certain which side light bulb had failed unless of course each bulb had its own circuit.Im pretty sure c,vans arnt wired up this way,mine definently isnt.(2009)
Hopefully, 9 years on the OP has fixed his problemSvend said:My audible alarm come on if there is a light or indicator failure on the trailer or caravan. To test take a bulb out and the the alarm start. I found out after it didn't come on when I used the indicator on my caravan. I then tried on my daughter's trailer and the audible alarm came on to indicate bulb failure. It also gave a single beeb when the brake was pressed to indicate another bulb failure. The car is a Hyundai i40 Detachable Towbar fitted by main dealer prior to delivery
Dustydog said:Hopefully, 9 years on the OP has fixed his problem