Trailer Electrics - Advice Needed (Rear Tail Light)

Question

Got a horse trailer, which seems to blow the fuse in my car for the 'Right Hand Tail Light'.

When using the trailer, it will blow the fuse (not right away), knocking out the rear tail light on my car, and the rear tail light cluster (not indicators) on the trailer.

I've followed the electric cable and it seems to be sound.

However, I've looked at the tail light holder (see image). It looks corroded. Could that be the reason is eventually blows the fuse whilst in use?

Is that likely to be the culprit? Am I better leaving the bulb out so that it doesn't blow the fuse, or leave bulb in?

Any advice appreciated as to whether I can clean it up or whether it needs a new holder.

Thanks!

Answer 1

Most likely there is a short circuit somewhere in the tail light circuit in the trailer's wiring, which will be causing the car's fuse to blow.

To test this, get hold of a digital multimeter (a cheap DIY shop one will be fine), and set it to continuity mode. With the trailer not plugged into the car, Take the bulb out of the right hand tail light, and test between the contacts in the holder - if there is a short the meter will buzz. Check also at the plug end between the tail light connection and the common return.

It's then a case of trial and error to track down the location of the short - it may be, for example, that the wiring has chafed on the frame of the trailer and worn through the insulation.

The photo you've posted doesn't look had enough to cause a failure, but it might be worse inside the bulb holder itself.

Answer 2

Thank you. I've conducted the test, and there is no buzzing on the corroded part. If I test the contact at the top of the picture (that is clean and does not blow the fuse). I get an audible buzz.

I have tried the opposite tail light and I can get an audible buzz on all contacts.