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Red battery warning light intermitant error

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Steve1000

Guest
Hi does anybody else have the problem where the reb (battery) electrical warning light comes on sporadically even when stopped in traffic. When this happens the windscreen heating element wil not work. I have had this problem for a couple of months now, it is only the heated windscreen that is affected.
I have measured the charge on the battery and the charge going into it and they are OK. Does anybody have an idea how to resolve it before i go and throw my hard earned money at Ford?
 

un1eash

Distinguished Member
Did you do a drop test on the battery or just measure the voltage? as the voltage wont tell you much. I would get a proper battery test done then check that the alternator is putting out enough voltage too.

It sounds more like a charging issue, similar thing happens alot with the MR2's when the IC regulator goes.
 
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Steve1000

Guest
Hi Sorry yeah that would have been usefull to list the car details.

05 Ford Focus Zetec Climate 1.6 Automatic. with 18,000 miles
 
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Honeywell1945

Guest
This is a safety feature , low battery voltage will disable the heated screen due to its heavy load , it would drain the battery in seconds otherwise .

We had a similar fault on a Ford , a new alternator , £175 supplied & fitted , from my local garage cured it .

Before you do , as mentioned check the battery terminals for tightness & the electrolyte level in the cells . If it is the battery then you must get a silver battery , it has a sensing circuit on it that Ford use for smart charging .

What voltage are you reading ?
 
Last edited by a moderator:
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Steve1000

Guest
About 1000rpm, but it sometimes lights up when i am travelling down the motorway at 69.9 mph :D
Or while driving around locally.
 
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Honeywell1945

Guest
About 1000rpm, but it sometimes lights up when i am travelling down the motorway at 69.9 mph :D
Or while driving around locally.

Alternator I'd say , ours did the same which was puzzling at the time .

Maybe get a reconditioned one or 2nd hand from a scrappie to check , £25 or thereabouts .

Our replacement was a genuine Lucas supplied & fitted , Ford wanted nearly £350 fitted from memory .
 

un1eash

Distinguished Member
Even if the voltage reads near 14v at idle there can still be a problem. Check the yellow pages and find a place that does recon alternators, they will be able to tell you if the alternator has had it.
 

sean5302

Banned
Nothing wrong with the tickover speed.

That leaves you with the alternator exciter wire or the alternator itself.

I'd try and trace the exciter wire plug connection. They often get corroded situated where they are (under the gearbox / clutch bellhousing area.)
 

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