Towbar wiring on 2008 Relay van.

[paul in normandy]

Fitted towbar OK - its a Brink one and very simple fitting. But I've got a problem with the wiring. Connected into the correct wires close to the rear light units. Indicators work fine on both sides, but I've got a problem with the side and brake lights. When the lighting board is connected into the towing socket the sidelights come on for about 5 seconds then go off / switch off lights, switch back on, lights on for 5 secs etc ad infinitum...... It does the same on both the lighting and brake light circuits. Any ideas where to start looking in order to rectify the problem. Many thanks for any assistance.

[GiveMeABreak]

We'll need your VIN in order to check the correct lighting circuit.

[paul in normandy]

VF7**************[VIN obfuscated, can be read by forum staff] is the VIN no.
Thanks

[GiveMeABreak]

Ok, just so you know, data for the Relay and Boxer vans is slightly better than useless - probably because these are Fiats / Ford combos with nothing Citroen or Peugeot in them. The wiring numbers are non-descript so I cannot provide you with specifics - but you should be able to work out what is what. I will show these individually for each lamp - once you identify the earths, the remaining should be the power.

Brake Lamps:

2630: rear LH lamp unit on the body 2635: right-hand tail lamp 2110: additional brake lamps So anything 'MC' is an earth point - MC69, MC70 etc.

Rear Sidelights

2630: Rear LH lamp unit on the body	2635: right-hand tail lamp

Reversing Lights

2630: Rear LH lamp unit on the body 2635: Right-hand tail lamp 2200: Reverse lamp switch

Fog Lamps

2630: rear LH lamp unit on the body 2635: right-hand tail lamp

Hopefully this is what you need.

[paul in normandy]

Thanks for that. I've managed to work out which wires are which, the problem I'm trying to resolve is why the side and brake lights work correctly until the towing socket is connected, and then they will work for only a couple of seconds before going off.

[GiveMeABreak]

May be something to do with the load on the circuit... A lot of cars have a separate trailer fuse box that is connected to the battery directly and then supplies fused power to the trailer and cuts out the reversing assistance / activates a special ESP programme for towing.