bmw bulb out light on dashboard computer

Certain the centre brake light if fitted is working? That caught me out as it indicates a driver's side fault on mine...

check the voltage on the earth side of each bulb holder while the light is on, ideally it should be zero, clean or modify the one with the highest reading and see what happens.

the bulb holders on the rear suffer from burnt contacts, if you need to know what series BMW you have just look on the side of one of the bonnet struts, the series is printed on one of them.

"Dave Plowman (News)" wrote in news: snipped-for-privacy@davenoise.co.uk:

Centre brake light seems ok as are both bulbs on the reg plate....

"Mrcheerful" wrote in news:8zApm.77148$ snipped-for-privacy@text.news.virginmedia.com:

Thanks for this but could you be a bit more specific on how i do this ? I have a voltmeter but unsure of what to do wrt above suggestion.

"reg" wrote in news:h86mg3$crd$ snipped-for-privacy@aioe.org:

Thanks, does cleaning them help ? If so what to clean them with ?

Fine emery paper

Sadly, you may have wasted your money on the new cluster.

If the connection is a small, black flat one, the problem is one of design. The earth pin on both the plug and socket part are woefully under- sized. You can often see that the earth wire in the loom has been overheated. If this is the case, the other side will be just as bad.

Trace out which of the connection bars in the cluster is the earth, temporarily wrap a piece of wire around the bar, and connect the other end of the wire to a good earth. The mounting point for the rear lens is convenient.

If the fault is then cleared, you just have to find a safe way of making the temporary connection permanent. Best way if you can is to drill and tap the bar 3mm. Easiest bodge is to keep the wire in place with a cable tie.

CAUTION! Make absolutely certain that the bar you connect the new earth wire to *is* the earth one! If in doubt, seek help!

Chris

Why did you buy a new bulb when you knew none of them were out? You have already stated you know what the problem might be and how to fix it, so what are you asking?

Washing up liquid. I get the feeling you are having a bit of a laugh here. First you stated you didn't have a bulb out but bought a new one. Then you had a multimeter but didn't know how to measure the voltage going to a bulb, now you want to know what to clean a contact with! You have been told this will help and you instantly asked if it would help! Does it get any worse, or do you not know how to use your keyboard. Just scrap the car.

That's never recommended for electrical contacts as it can leave small particles imbedded. Use a contact cleaner. If the contacts are so burnt they need reshaping use a file designed for this - preferably a fine diamond coated one. But smaller contacts resulting from this might reduce the pressure and cause it to happen all over again.

The rear light clusters on my E39 have very well made bulb holders. The multi-pin connector on the unit and cable is said to sometimes give problems.

Where does the OP say he has replaced the bulb?

Chris

You can just ignore the thread. Although if you use washing up liquid on contacts that may be a bit of a challenge for you.

In the case of a switch contact or an armature I'd agree, but it'll make sod all difference to a lamp cluster.

Ho hum I get the feeling I should not take the bait on this one but...

"Roger" wrote in news:h87rn7$amu$ snipped-for-privacy@news.albasani.net:

Yep, cos I was advised the likely cause was the bulbholder cluster...

Well original advice was "check the voltage on the earth side of each bulb holder while the light is on" and I was not clear which points to measure the voltage from

Well its interesting that its so obvious to you yet opinion is divided in the responses thus far...

Cheers for the venomous unhelpful response, apologies for not knowing enough on the subject to be worthy of posting (in your opionion)

Chris Whelan wrote in news:nDLpm.84931 $ snipped-for-privacy@newsfe11.ams:

Roger

As Chris correctly points out I did not say I replaced the bulb. If you read again you will see I actually said I got a new bulb holder.

With a decent DVM you can measure the state of any wiring or connector by checking the voltage drop across one conductor while it's working. To check the bulbholder connect your meter on the 2 volt range between bulb body and car chassis. This will show if any problems are present. It should only read a few millivolts. Do the same between the centre contact and supply. This is a bit easier than measuring the 12 volts at various points and calculating the difference - and shows whether it's a supply or ground fault.

on 08/09/2009, dkh supposed :

Connect a voltmeter, set on the 2v DC range, one probe tip on the lampholders metalwork and the other on a really good ground connection on the car. See if there is any voltage between the two points when the lamp is lit.

It might also be worth replacing the lamps. On my car, the lamp only needed to be slightly intermitant for the failure light to come on and stay on despite the lamp still being lit. My lamp had an internal fault, but not actually blown.