bikerack to motorhome towbar - electrics problem

when yo say bike rack electrics I am assuming you have repeater board/lights that you hang on the back of the bikes when they are on the rack??

Are you sure all the pins on the plug and socket are clean and corrosion free. Try giving them a spray with switch cleaner or WD40 before connecting them.

peedee

If none of the lights are working then the problem is most likely the earth connection in the plug. Take the plug apart and check that each individual cable is actually making a good contact in the pin. Unscrew each cable and take the cable out. Sometimes it can look like a good connection but the screw may be bearing on the plastic insultaion only and you may find the wire inside is coroded and not actually connected to the pin. If necessary then strip back the insulation and make a new connection. When reassembling make sure the cable grip is tightly holding the outer insulation and that the individual cables are slack, so a pull on the cable does not pull one of the cables out of the pin in the plug.

If the whole rig isn't lighting up, it would suggest that a master fuse somewhere has failed.