Rear light failure

[sgould]

Three years ago the right hand tail light cluster failed.  I found that the earth connection had melted!

This evening, I found that the left hand side had failed the same way.  Last time I soldered a wire through the body for the earth to by-pass the connector. It's worked well since.  I shall have to do the same again tomorrow.

Pictures from the previous time.  Burnt connector.  Missing pin in the holder and the new (blue) wire.

[carrera]

That reminds me of doing a similar repair on a VW Jetta many years ago, to repair a track, rather than provide an earth..

Any theories as to why there is so much heat causing the connector to warm up and fail

[sgould]

There is clearly a high resistance in the pin connection; either in the pin to socket, or the wire crimping to the pin.  The earth is for the tail light, the brake light and the indicator.  I can see the Earth taking current from all three sources at the same time - at night when braking for a turning.  But why that connection should fail after 11 years on the right and 15 years on the left is puzzling.

The right side just failed.  The left side has been throwing random warnings on one or other of the circuits for a couple of weeks. I cleaned contacts and the warnings went away for a while. It was only yesterday that all three warnings appeared together and wouldn't clear.  I had a look and found the connector stuck.  I turned on the lights and wiggled the connector and the lights came on, dimly.  Then the connector released itself, along with a string of melted plastic.  That was when I realised that the connector had failed in the same way as the other side.

I have never replaced any of the bulbs or used LEDs or anything.  So I'm at a loss as to the cause.  But the solution should be straightforward.