INTERMITTENT REAR LIGHT FAILURE WARNING

[collywobble]

Had a couple of occasions over the last couple of weeks when the 'rear light failure' warning message came up. First time SWMBO was out on her own, tonight going over to my son's to take birthday present to youngest grandson, put sidelights on and message came up again. Got to son's and send SWMBO to stand at the back while I operate indicators and brakes - all lights working correctly.  Turn sidelights off and on again - now no message! 

So, where should I start first, look for a faulty earth or a loose bulb?

All suggestions gratefully received.

[TomPaine]

Is it not the case that you often get the failure message before they actually fail - because the system picks up the increased resistance of a failing bulb?

[Audax]

I've seen it in that case shortly before they fail, sometimes the filaments break too but fall in such a way that they still make contact. If you remove the bulbs and look at them very carefully (if you have poor eyesight you might need a magnifying glass) you can actually see the condition of the filament. New filaments are nice and regular in shape, old filaments are quite obvious, they almost look like they have gone rusty.

I'd suggest for how much bother it is removing the bulbs and replacing them all anyway. A decent set to do the rear of a 9-5 shouldn't be more than a tenner, then just keep all the good old ones as spares.

[MartinMc711]

Kept getting intermittent Dipped Beam Failure on my 9-3, while the light clearly worked, had only replaced the bulb a few months previously.

Took a closer look and the lamp holder was smoking when the light was on!

Replaced the bulb and all fine - just a dodgy bulb I guess.

[Griffin Dave]

Have you checked reversing light ?

[Hamish McSporran]

I get an occasional brake light failure warning too. Dodgy connection on the high level light (bulbs on a '53, not LEDs). Works when it feels like it really.

[weetabixface]

Is it not the case that you often get the failure message before they actually fail - because the system picks up the increased resistance of a failing bulb?

that is certainly my experience, checking all the bulbs is a PITA but there will likely be one that is on its way out

W