Brake Bulb Failure

[Guest Aussie Phil]

I've got an interesting problem and I'd appreciate any help I can get.

 

The brake bulbs on my Galaxy (2001 1.9 TDI Zetec) keep failing. I have to replace both brake bulbs every couple of months when one or other of them has failed. I've taken to replacing them as a pair as when one side has gone as the other side soon follows. In the last 2 years its had over 8 sets. No other bulbs on the Galaxy behave like this.

 

I've checked all contacts etc in the rear light clusters and the bulb has definitely gone although the glass is not in anyway discoloured. The bulb still looks brand new. The tail light filament, in the same bulb is always OK. The brake filament is never "blown" as would be expected with a short etc - but the circuit filament is definitely open circuit. Close examination usually shows one end disconnected. I can believe an odd case of this but every bulb?? The bulbs are Bosch Type 380 purchased from Halfords.

 

I also have a non Ford cruise control fitted which has a sensor wire to the braking circuit. This sensing wire gets an earth via the brake bulbs to allow the cruise to set. Hence last week when BOTH bulbs failed I couldn't set the cruise. I thought perhaps this circuit may be prematurely aging the bulbs but apparently it just senses the earth via the bulb. I can measure no leakage voltage etc at the bulb with the cruise control ON. I have contacted the cruise module manufacturer and they advise no known problems.

 

I'm at my wits end about this and its dangerous, not to mention illegal, to have no brake lights.

 

 

 

 

:47:

[Dave-G]

Would you perhaps be buying them from one of them el-cheapo smiling asian places?

[NikpV]

measure no leakage voltage etc at the bulb with the cruise control ON

 

its leakage current you need to measure although I can't see how this could increase in the filament, unless there is some voltage spike being produced which gives rise to a temporarilty higher current than normal this would prematurely age the bulb. I can't understand what you mean by sensing the earth?

[tim-spam]

Perhaps your brake light switch is on its way out - sometimes a poor contact can cause a bulb to flicker at high frequency causing premature failure. I would however consider this a bit of a long shot, as I would think that the time taken between poor contact and total switch failure would be comparatively short, but it may be worth checking the resistance across the switch contacts and the voltage at the bulbs.

[Ivor_E_Tower]

On my first car, I fitted rear fog lamps (in the days long ago before these things were mandatory). The warning lamp in the switch kept blowing - no obvious reason, it just seems to be one of those things that some cars blow certain bulbs regularly.

[familyman]

The brake lights on my fiat blow with tedious regularity- i've cleaned contacts ,checked wiring ,no obvious reason for them to blow, they can go for months without blowing ,then go through a phase of blowing twice a week ,could just be one of those things that are sent to try us (and certainly succeeds!!)

[marinabrid]

hi all why not try the new long life heavy duty filament bulbs available in 380 382 and all headlite sidelight types the filament is thicker than normal, i sell lots to the taxi boys and they say they do last much longer. just a thought get them here. My Webshop they are called ring long life bulbs

[seatkid]

The only things that kill bulbs prematurely

 

1. Overvoltage - unlikely here as other bulbs would blow too - and it takes a lot of overvolts to kill an auto bulb. They are more or less immune to "spikes".

 

2. Vibration and shock - check the security of the holder and the assembly - is it sloppy?

 

3. Bad manufacture - have you bought the bulbs from the same place? - Its likely to be a bad batch especially if the filament is being detached at the end - that definitely shouldn't happen/ The name Bosch is no guarantee of quality when it comes to consumables (bulbs,batteries,filters etc) they are generally not actually made by Bosch.... take them back to Halfords and complain, and try a different brand.

[tiny]

One of my old bikes used to blow rear bulbs like there was no tomorrow, not the brake but the side light one it must of been getting over voltage as I found it was only happening at high revs. I was subsequently told that it could of been a fault with the charging system, this seems unlikely with a brake light as its only on intermittently, I cured it by fitting a 24v bulb! Not to be recommended but it did the job.

 

Try seeing if you can isolate the problem to your after market cruise control by not using it for a while and seeing if it still blows bulbs