Problem with trailer lights not working

[Oredden]

Hi, we have a trailer at work a large car transport trailer. All the lights suddenly stop working, tested electrics on the van with a lighting board, all working perfectly. When I connect a wire to the white wires in the plug, and the other end to the bare metal on the tow bar on the van, they work. Rang the manufactures of the trailer, they sad there is no ground connection to the trailer chassis because it's not needed with that loom aparently . Any advice would be appreciated! Thanks

 

[telectrix]

sounds like you've lost the ground in the loom,

 

[ruston]

As @telectrix . You have probably lost the earth , or the lamps are not compatible with the canbus system.
The white wire is the earth wire from the host vehicle . The trailer chassis is only connected to the earth of the vehicle through fortuitous contact through the tow bar ball. It may be linked from the accessories to earth but it needs the white wire to function correctly ; unless I am out of date.
Did they ever work correctly? or was this problem from the start

 

[Oredden]

As @telectrix . You have probably lost the earth , or the lamps are not compatible with the canbus system.
The white wire is the earth wire from the host vehicle . The trailer chassis is only connected to the earth of the vehicle through fortuitous contact through the tow bar ball. It may be linked from the accessories to earth but it needs the white wire to function correctly ; unless I am out of date.
Did they ever work correctly? or was this problem from the start

Thanks,
We have had the trailer a couple of years, only used it 6 times, it worked well before

 

[ruston]

In view that the trailer board worked from the vehicle with no problem I would check the trailer plug then to see if the earth has good contact with corresponding pin, and check the condition of the cable , if it has been running with a bad connection it could be almost dust lol. If the cores have blackened they are goosed.

 

[Oredden]

In view that the trailer board worked from the vehicle with no problem I would check the trailer plug then to see if the earth has good contact with corresponding pin, and check the condition of the cable , if it has been running with a bad connection it could be almost dust lol. If the cores have blackened they are goosed.

Changed the van for the car same issue, th inside of the trailer plug was wet and rusty inside, I cleaned it out but no change, it's 3 cables going into a euro plug which go's into uk adapter

 

[ruston]

If it all worked well before it seems a connection problem at the trailer/plug . The rust and water will be a contributing factor . I am not familiar with the Euro plug adaptor but the rusty plug is bad news. You need good clean connections.