Ford Focus Conundrum

It would seem as though the alternator voltage control was giving too high a voltage to the battery. A decent auto electrician could measure this and advize. 

Cheers

Bill

Timbo, have you tried sourcing your replacement bulbs from somewhere else - perhaps a poor batch.

If the fuse is blowing it means the fuse is overloaded

Wrong bulbs (maybe the blow process is causing a short circuit inside the bulb)  

Wrong fuse (unless its a bad quality 1 or 2 amp - I doubt it)

I can't see why only these lights are blowing unless they are poor quality or below spec.  Other low power bulbs live in tail, front, & panel lights & no reason why these should not blow as well.  

+1 for Bill - go get it checked out by an auto-electrician as it could be your alternator voltage regulator is too high & that needs a specialist. They will also be able to check all the other stuff & get it nailed. 

NB:  Only go to a garage with a genuine auto-electrician or an auto-electrical specialist shop.

it is not the bulb, I guess the alternator stabization is at fault  s//  regulator     voltage not stable , increased volts causes more current, lamp blows

Is there a flexi cable through the hatch/rear door that has worn insulation?

It would seem that if it's  limited to only a couple of bulbs over voltage might not be the answer unless these are very weak bulbs.

Good tip H,  only problem is if Timbo has written it correctly & I understand it right,  the bulbs blow as well as the fuse. If it is the tail gate hinge cable shorting, that doesn't account for the bulbs blowing. 

Problem is the market has a load of low quality bulbs around that are not spec'd correctly for automotive 12v.  Although they say 12v on the box & bulb, they should be spec’d for around 14v for all car & truck 12v systems.  I advise with all bulbs is be sure you can see its from a well-known make.

Again I would repeat to go for an alternator check.  The US spec Focus alternator is 105 amps - a good size & able to poke out a lot of amps & volts if the regulator is going bad its well able to blow low spec bulbs. 

Thanks for your advice everyone. To clarify, the bulbs are OK, it is just the fuse blowing. If I put in a new fuse the bulbs come on for a few seconds and then the fuse blows. But only while the car is running, so the alternator is something I hadn't considered, the car is due for a routine service and I always take it to a Ford main dealer so I will get them to check it out.

Cheers

Tim

Still doesn't make sense,  if it was the alternator other bulbs would burn out & it would not blow the tail light fuse.  

Could be something like a cross connection in the tailgate hinge area across to the screen heater ????.  

Go get it checked out by the garage.  And let us all know what it was for sure.  

I was wondering that but I have managed to inspect the wiring loom in the tailgate and the first part of the car and all seems OK. But you are right a Ford Main Dealer should have all the right diagnostic equipment and hopefully should be able to identify the problem.

Tim

tail lamps are very low there resistance is so they are fragile

Yes the fuse is rated at 7.5

I will let you know the outcome.

Tim

Just a thought, but does the fuse feed anything else? Perfault the fault is elsewhere...

Good point, there has to be other items on the circuit. Ford would not provide a fused circuit just for rear number plate lights

Please excuse my spelling, replying on an iPhone is never a good idea with chubby fingers!

Had a look at this, it seems the licence plate lights are the only thing on that circuit, nothing else seems not to work.

On a separate note, have been listening to my unitiserve most of the day thru NDac, XPS2, 252, 300 and SL2's - fantastic!!!!

Tim