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Brake-light fuse blowing.


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2001 90TD5; I was alerted to the lack of brake-lights by a relatively-friendly policeman, who followed me home through today's downpour.

Investigation showed that the brake-light fuse was blown. A new fuse blew immediately.

I've disconnected the harness to the trailer-socket, knowing that water ingress into these often causes electrical systems to develop 'issues'.

Pulled the wires off the feed to the HRW/high-level brake light on the tailgate: fuse still blew.

Removed both rear lights from the body and unplugged them from the harness: fuse no longer blew.

Reconnected the rear lights one at a time, expecting to find one of them triggered a fuse-blowing incident.

It didn't: I now have both rear lights and the high-level brakelight connected up and working.

Colour me confused. I'm wondering if it's possible for there to be an intermittent short-circuit in the rear-light bulbs?

In the meantime I've connected a 'beeper' to the brake-light circuit so I get an audible indication that the brake-lights are still getting power and the fuse hasn't blown.

Apart from that, any suggestions as to where I should look next?


"However hard a Badger tries, Otters will always be better".

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Firstly spray wd40 or similar into the bulb holders.

Secondly check the earth at the back of the landy - mine fell to bits!

Thanks for pointing me in the right direction - I just pulled out both rear-light units and gave them a really good inspection: offside one was fine but the nearside one had a bit of corrosion on the contacts (a year or so back it had filled up with water and the glass part of the bulb shattered!).

This time it was clean and dry in there but looking closely at it I could see that one of the two springy metal contacts in the base of the holder had got distorted and was now in a position where it could contact against the outer metal shell of the bulb - which of course is earthed!

Which explains where the juice was going, and why the fuses kept blowing.... A quick 'tweak' with some needle-nose pliers bent the contact back into a slightly less-silly shape, and a squib of 'electrolube' contact-spray (better than WD40) seems to have it all sorted now.


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