TFC1 & 2: Fog cut-out relays

These relays are designed to switch off the foglamp(s) of a towing vehicle when the foglamp of a towed trailer is on. The reason for turning off the vehicle foglamp is to avoid a distracting glare being reflected by the towed trailer, especially if the trailer is a caravan.
A fog cut-out relay is, in fact, a combined monitor and relay: the relay that switches off the towing vehicle's foglamp is switched by a monitoring circuit that operates when it detects current flowing through it to the trailer foglamp. The switched side is fitted in line in the vehicle foglamp circuit and the monitoring side is fitted in the cable going to pin 2 of the vehicle's trailer socket. It is necessary before fitting to cut the wire that supplies the vehicle foglamp.
1. Wire the 12N socket according to the instructions with the flasher relay or monitor you fit but do not connect the free end of the blue (fog lamp) wire in the 7-core cable.
2. Carefully follow the instructions above to complete the installation by adding the fog cut out relay.
3. Where the diagram shows that you have to cut the vehicle's own wiring to install the relay in line, connect the cut ends of the wires to the appropriate screw terminals of the relay.
4. The fog cut out relay will turn one or both of the vehicle's fog lights off if a trailer fog lamp is connected. When the trailer fog lamp is not present, the vehicle fog lights should work as normal.
5. Use a suitable test board to test the circuits. Make sure the vehicle's fog light(s) and the trailer fog lamp(s) are working correctly and that no warning lamps are showing.