Towbar Wiring | 12N Wiring

Before you start

Examine the car carefully to see that all electrical circuits are working correctly and that no warning lights are showing.

Decide whether to disconnect the battery. Take into account:

  • With many modern cars it is better to take power from a source such as the bus bars at the back of the fusebox. If the car has a battery status display, it is probably monitoring power input and output, and only using the alternator to replace the power it sees being consumed. If you take power directly from the battery in such cars, the system will not replace it and the battery will run down.)
  • Would disconnection disrupt memory circuits, etc? (You may need a device to keep memory circuits )
  • Can you make your electrical connections safely with the battery connected?

General Instruction, 12N boot fitting relays and monitors

  1. Find a suitable cable entry point, close to the trailer socket. (If you have to drill, select your spot with care, treat the edges of the hole with anti-rust paint, and insert a suitable grommet to protect the cable.)
  2. Wire the trailer socket, as shown in Chart A and mount it on the towbar. If you are using a 13-pin socket, the pin numbers for the "N" wiring are the same.  
  3. Lead the trailer socket cable into the boot through the prepared entry point. Make sure the cable is a snug fit in any grommet it passes through, to prevent fumes coming into the car.
If you need to take a power source for a bypass relay, etc.
  1. Route your power source cable(s) from the boot to the power source. Fit appropriate fuses in line in the cable, close to the power source. Do not connect yet .
  2. When routing the cable, take care to route it where it will not be cut or crushed. Pay particular attention to points where the cable passes through bulkheads, etc.

    In all cases

  3. Use a probe tester to identify the appropriate wires in the vehicle loom.
  4. Follow the instructions in Chart A and connect together your trailer socket cable, your relay(s) and/or monitor and the appropriate wires in the vehicle loom.
  5. If applicable, connect your power cable to the power source and insert the fuse(s).
  6. Use a suitable test board to test the circuits, preferably with the alternator charging. Make sure any "Tell-tale" warning light or buzzer is working correctly.

CHART A

Socket
Pin No.		 Cable
colour		  to  Relay wire
colour or
terminal No.		 Relay wire
colour or
terminal No.		  to  Vehicle Circuit
1 Yellow to See relay details to LH Flasher
2 Blue to See relay details to Fog Lamp
3 White to Chassis White to Chassis earth
4 Green to See relay details to RH Flasher
5 Brown to See relay details to RH tail light
6 Red to See relay details to Brake Lights
7 Black to See relay details to LH tail light