Towbar electrics

I have no power to my light board that I have put on my scooter rack, the light board is brand new so I don’t think it’s that, I have found the 2 fuses behind the drivers seat and they are both ok,  are there any other fuses for the electrics I could check

Do you have a bypass relay for the electrics? I often get nil electrics on the trailer, but unplugging the connection to the bypass and reconnecting always cures it?

I have no idea, the Towbar and electrics were fitted when I bought the van, and this is the first time I have used it

Where would one find the bypass relay?

Where ever it was fitted. Mine is with the hab battery under the passenger seat. Follow the multi cable from the rear socket, that plugs into it.

Do you have a neighbour with a tow bar on their car that you could plug your board in to, in order to test?

You only need a single bad earth on the trailer board and none of it will work?

Checked another lighting board in the electrical tow bar connector and nothing at all , I have power to one side of the fuse behind the drivers seat and the fuses check out ok, all wires are connected correctly in the socket, more testing when I get home tomorrow then I think it will be an auto sparky

Freelander first check you have an earth on pin 3 white wire of the trailer socket.without this nothing will work The installation will have either a generic relay box fitted or a dedicated wiring kit also with a control box. As these kits are not motorhome specific , the required permanent 12v supply is more likely taken from either the  engine battery or in the case of a dedicated kit the vehicle fusebox either  internal or engine bay so check both positions for a fused supply hopefully marked trailer supply. Not many fitters take anything to do with motorhome  Sargent electrics. If a generic bypass relay box fitted check the nearside rear  light cluster as this is a popular area to install the box . An earth is present there and access to most of required wiring is at the rear of the light cluster. You could also follow the multicore cable from the rear of the trailer socket into the vehicle.  If it disappears into the nearside corner then this may be a clue! From memory the last dedicated kit I fitted had the control box placed in the offside rear light cluster area and was fused under the bonnet within the engine fuse box.

Thanks, I found some fitting instructions on the PF Jones tow bar website that show what you mention ,so I will investigate further when home ,many thanks

I've had towbar fitted vehicles for fifty years now.  All three of my current 'fleet' are fitted.  Failure to work has always been down to corrosion, either where the leads fit the socket or the actual contacts in the plug or socket.  At one time you could buy little wire brushes to clean them but I haven't seen any for a while.  The back of the socket in particular is often poorly protected from dirt and spray and is almost a 'service item'.

Times have moved on, in my youth the tow bar was a length of angle iron bolted on instead of the bumper and the electrics were wires poked in to the bullet connectors in the boot!

Tony Comber

Sorted the electrics for the tow bar, under the van and traced the cable back to the battery box, it’s not a vehicle specific wiring loom that was used and the connection block was inside the battery compartment, easily enough to find the problem as shown in the photos, not very securely crimped 

A length of new cable and new crimps fitted and now working tow bar electrics[You must be registered and logged in to see this link.]

Great news.

I'm going to guess that it took longer to find the issue, than it did to fix the issue?

Glad you found it ! Looks a professional install.... that stray unfused live  wire perilously close to an earth could have ended in grief.
       Strange way of doing things , it is much easier to take a single core permanent 12v supply to the back and mount the bypass relay in the rear near the lights. It looks like they have taken 2 multi core cables  to the  back from the battery box , one to pick up the light signals from the rear lamps  and one to supply the trailer socket.

The wire was fused just not crimped very well , I have ordered a new double fuse and will remake all the connections, yes not the way I would have installed it, I think it’s always worth buying the correct vehicle specific wiring kits, but we now have rear lights on the trailer board