Brake activation blows fuse

[davinho]

Originally Posted by davestewart2

Latest and greatest:

- Checked the break lights and running light and they all work okay.
- Disconnected the blue wire (brake on AS) activated brake pedal in Tow Vehicle (Fuse blows).

- Haven't managed to determine which line the fuse is in yet as it was snowing a good part of the weekend and freezing cold.

- all lights checked and no problem there.
- eliminated tow vehicle
- only thing we haven't managed to check is the wheel units themselves
- phew!

[davinho]

Originally Posted by WK57ABF

Dave,

There is only one fuse on the brake controller and that is on the black feed to the controller which is uaually a 20 or 30 amp circuit breaker.

Check that the blue wire from the brake controller, 14 gauge (20 amp) for a single axle, goes straight to the brakes with no other connections or fuse in that line.

Don't know if you have changed the trailer end 7 blade US plug for a UK round pin plug but the wiring should be :

left turn - red
right turn - brown
ground - white
charge wire - black
running lights - green
brakes - blue

Now the most important part of the US to UK conversion - a separate wire will have to be run from the socket (trailer end) to the stop lights.

In our trailer rear light cluster, we disconnected the centre back-up light (clear lens) and fitted an amber lens and used that llight for turn signals. The other two red lenses were used for running and stop lights.

I suspect that your electrician is not familiar with the US two bulb system and in converting to our 3 bulb system has in some way used the blue brake wire to operate bulbs.

I know how to convert to UK wiring but find it difficult to put down on paper!!!

Incidentally, is your ex-electrician/light convertion guy the infamous Mr. R...., who is now wanted by the police?

John in the UK

John,

A bit of progress this weekend

The wiring you stated above is spot on and the yellow wire (not mentioned above) is used as the brake light, so brake controller and brake lights are on two different circuits on the caravan. The current draw on the brake controller wire was about 6 amps, which for a single axle is okay. When I connected the battery across white and black it blew the fuse in my multimeter, but this wire wasn't connected with the previous wiring?

Anyway, this leads me to believe it is not the cars wiring, so am calling a mobile auto electrician tomorrow!

More to come.

Dave

[davinho]

Finally got to the bottom of the problem!

Had a mobile towbar fitting company come look:

- plugged the test box into the truck and all worked fine
- attached the lead from the trailer to the truck and blew a fuse.
- the fuse was in the lighting circuit which we had already checked by connecting a battery across each circuit individually and checking that they worked properly.
- the plug which connects the trailer to the truck had faulty wiring. This particular one was a sealed version that we couldn't rewire, so buying a new one and length of cable sorted out the issue.
- planning on getting out into the Highlands of Scotland and over to the Western Isles too this Summer!

Thanks to all those who contributed with suggestions and especially to John, here in the UK.......

Dave