The right boat trailer part

About UK/European Trailer Wiring Codes

The most common boat trailer part to fail is the boat trailer electrical system. It is subject to water ingress into light fittings and lighting connectors. Also this has the effect of rotting out the copper electrical cables so they tend to need rewiring on a regular basis.

The next most common failure point are the wheel bearings, subject to salt water ingress and corrosion as they sit in the back yard for long periods and tend to seizes up.

Initially the balls corrode at the contact point with the race and when used the material flakes off, the heat is then generated with the friction and ultimately the bearing grease runs out and the bearing fails.

So what does this mean for you the boat owner, well if you don't look after your trailer you end up stranded at home when the season starts, or left stranded at the ramp. If you are really unlucky your electrical lights on the trailer fail and the highway patrol gives you a fine.

The right boat-trailer part

The UK and Europe use ISO Standards with two 7 pin plugs.

12N Socket Standard

1 (L) – Yellow - Left hand indicator light

2 (54G) – Blue - Rear fog light

3 (31) – White - Ground/earth

4 (R) – Green - Right hand indicator light

5 (58R) – Brown - RHS Tail/Licence plate light

6 (54) – Red - Stop (Brake) light

7 (58L) – Black - LHS Tail/Licence plate light



12S Socket Supplementary

12S Socket Supplementary

1 Yellow - Reverse Light or Brake System

2 Blue - Spare

3 White - Return for Pin 4

4 Green - Power Auxiliaries/Battery

5 Brown - Warning Lamp

6 Red - Refrigerator

7 Black - Return for Pin 6


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