Rear light failure

Started by sgould, 12 May 2026, 10:00:21 PM

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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.


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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
9-5 Aero Estates, 2002 Cosmic Blue, 2003 Steel Grey, 2003 Graphite Green, 2004 9-5 Glacier Blue 2.0 saloon, 2004 Nocturne Blue 2.2 diesel estate, 2006 & 2008 Black Aero saloons, 1998 9000 CSE with Aero engine, 9-5 NG Aero XWD Turbo4, 9-5 NG Aero XWD TTiD, 9-5 NG Aero 2WD Turbo4

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.
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sgould

All done and back together.  No pictures because they would be much the same as the others and I was dodging in and out between the rain and hailstorms.
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carrera

Always nice to have a happy ending ...
9-5 Aero Estates, 2002 Cosmic Blue, 2003 Steel Grey, 2003 Graphite Green, 2004 9-5 Glacier Blue 2.0 saloon, 2004 Nocturne Blue 2.2 diesel estate, 2006 & 2008 Black Aero saloons, 1998 9000 CSE with Aero engine, 9-5 NG Aero XWD Turbo4, 9-5 NG Aero XWD TTiD, 9-5 NG Aero 2WD Turbo4

sgould

My wife reported an engine light on.  I checked the codes and there were 11...  The first 5 or six were related to the rear light cluster.  All three circuits.  These were generated before i by-passed the earth in the connector.  I cleared them and the only code relating to the engine light was the old P0089 fuel pressure one, which I cleared.

Still seems to be fine.
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carrera

Would the DTC's on the light circuits have popped up on SID, or are they simply silent errors.

The CEL popped I assume from your old phantom friend P0089 ?
9-5 Aero Estates, 2002 Cosmic Blue, 2003 Steel Grey, 2003 Graphite Green, 2004 9-5 Glacier Blue 2.0 saloon, 2004 Nocturne Blue 2.2 diesel estate, 2006 & 2008 Black Aero saloons, 1998 9000 CSE with Aero engine, 9-5 NG Aero XWD Turbo4, 9-5 NG Aero XWD TTiD, 9-5 NG Aero 2WD Turbo4

sgould

That's what I'm assuming on the P0089.  I turned it off and it hasn't come on again today.  I hope it stays off for a couple of days.  Wednesday is MOT day.

The light errors did come up as warnings on SID.  But they were erratic and came and went. But it seems the codes remain.  The other codes I ignored are related to the fuel level sensor that only works when fuel s below 75% and some for the door mirrors.
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