Bulb Failure Alert

[Cymro]

The bulb failure warining light appeared recently on my dashboard. I checked, and found that the bulb in the tailgate brake-light had failed. It proved easy to remove the trim, and replace the bulb.

However, the dashboard warining light continues to be illuminated. So I've checked every bulb, and every possible combination of lights, and every one is OK. I really have checked the lot.

So I wonder: after the warning light has been activated by a bulb failure, must the warning system be re-set? Unless I can clear it, the car will fail the MOT because a warning light is (wrongly) illuminated.

Any advice, please?

[CHUNKY CHIP]

Had this several times on cars and commercials you say checked bulbs do you mean actual check bulb in hand or visual as in lights on etc

This fault i have seen show for dim bulbs-bright bulbs- even cheap bulbs?

Also recheck the new bulb change it with another its easy to have a fault with a new bulb also and o/e fault stays there done it myself and spent hours looking something that was caused by a new part

cc

[Skodaboy]

I had a Volvo 240 estate and whenever I had a brake light failure, I always ended up replacing all 3 lamps as the system reads the resistance of the bulb circuit, the effect when replacing only 1 bulb left the system unbalanced. A used bulb will have a different resistance from that of a new bulb.

[CHUNKY CHIP]

mercs also like a set of bulbs done at the same time not just 1

[Cymro]

Many thanks for these replies.

I've discovered from my MOT tester that the car will not fail because of the false display of the bulb failure warning light. Nevertheless I do want to eliminate it, and I'll get new bulbs from Lexus for the 3 brake lights (I'm told that bulbs from an autopart dealer my not have exactly the stipulated resistances.)

Thanks for the advice.

[ihpj]

Quite agree with the diagnosis Re: resistance. Cheap bulbs lack necessary resistance characteristics the vehicle relies on for checking bulb failure, this is very common in comparable VAG Group/BMW/Merc. etc. so would expect with 'proper' bulb replaced, this should sort itself out.

[Cymro]

Problem solved!

Thanks to your advice, at last I have today bought another new 18w bulb to fit the central brake light - notwithstanding that the earlier replacement bulb works. I fitted the latest bulb (Lucas) - and YES! The bulb warning light no longer shows on the dashboard. So the system must be very sensitive to the bulb's resistance.

Many thanks for you advice.