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1.6Tdci - New Alternator Voltage Pulsating.

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#1 byfielder



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  • Name: Jamie
  • Ford Model: Focus 1.6Tdci
  • Year: 2005
  • Location: Hampshire

Posted 13 December 2011 - 09:47 PM

Hi, (Ford Focus 2005 1.6Tdci 100,000Miles)

I'm trying to help my brother ford focus that has been nothing but trouble since he bought it about a year ago.

This time, the battery warning indicator kept illuminating on and off while driving along, combined with the fact that the alternator was making a wurring (worn Bearing) noise made us assume that the alternator was kaput, so we replaced the alternator with a new unit.
Now when the engine is running all the overall voltage output from the new alternator is pulsating, and is really noticeable when the lights are on as they dim in and out, and the battery warning indicator is now flashing on and off but now permanently when running.

We have checked that the alternator drive belt is gripping well and tensioned ok (spring tensioner), and that the main battery terminal is nice and tight to the terminal on the alternator, and checked and re-checked the ford multi-pin connector that plugs to the unit and is also ok, but still no good.

My brother had bought his own diagnostic machine, plugged it in and it does not list any new faults.

Surely it cannot by a faulty new alternator can it? I cannot think if what else it can be... Any ideas?

My brother wants to sell the car but the flashing battery indicator light is putting potential buyers off, so it would be great to get it sorted.

This particular car has had a dreadful history of electrical / sensor problems with it and my brother has spent well over 1500 within the last year solving problems which later return. It has had a whole replacement instrument binnacle from Ford themselves as the old one was faulty causing the car to repeatedly break down...650 as well as countless replacement sensors and repeated computer diagnostic, re-mapping, and re-setting. But still the instrument binnacle lights up like a Christmas tree with battery and engine management lights reporting of yet more and more faults and the car looses power and sometimes cuts out.

It seems to be ok though at the moment it's just only the alternator problem at the moment.

Any help with be great. Thanks

Kind regards


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#2 jeebowhite


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  • Ford Model: Sea Grey Mondeo MKIV 1.8TDCi 140ps Zetec
  • Year: 2007
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Posted 14 December 2011 - 05:00 PM

I think you may have a faulty unit there, and if you have any guarantee with it, I would use it and get a replacement! it seems you have checked thoroughly everything else, but the pulsating of the brightness of the lights sounds very much like a faulty part to me!

#3 ToolBox


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  • Name: BRIAN
  • Ford Model: KUGA ZETEC 2.0 TDCI
  • Year: 2010
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Posted 14 December 2011 - 07:19 PM

When my Motorcycle Battery went t ts up the charge voltage was all over the place, may be worth substituting the Battery for a known good one,of the correct type, we are now at the time of year when Batteries just fail as the temperature drops and internal resistance rises.
Regards Brian

#4 jeebowhite


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Posted 15 December 2011 - 12:56 PM

Thats true, Although a new battery is a fee of 90+ so the question is, do you want to buy a new battery, and replace on the offchance (you wont see any real benefit, but it may stop you being stuffed like I was last winter! damn batteries! lol) so you would still benefit, or otherwise you might need to get the alternator tested and ensure that its not throwing dodgy outputs... Some garages will offer a free check of the alternator, so you may be able to sway them towards check and monitor for a brief period.


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