no,no,no,no,noooooo. Dont ever link sided lights. They are sided incase one develops a fault,so at least one is working. Is it blowing the front side light as well ?? Do you have trailer electrics wired up?? It sounds like you have a short somewhere. What you need is lots of patience,and to start stripping the loom out and following the wires back. Its a long drawn out affair...... Things to look for before hand,is the dash lights going out,glove box,has someone fitted a stereo and cut the wires. Just a couple of things to check before delving in to some loom stripping..