Hi, 

I am hoping someone can offer me some advice please. I have been having a problem with an intermittent battery light which comes on whilst driving ( it doesn't come on if i turn the key in the ignition and its sat idling) . I bought the car approx 5 years ago second hand ( it had just over 10k miles on the clock - currently is on about 55k ) 

This is is a short breakdown of what happens and what i have had looked at so far :-

What has been happening:-

• Battery light flashes on intermittently - usually appears anywhere between 5-25 minutes of driving. 
• Battery light occasionally comes on and then goes off for a bit but then comes back on again.
• Car has started juddering a little when sat waiting at traffic lights/ being stuck in traffic.
• Car struggling to start ( although this hasn't happened since i have had a new battery replacement). 
• Heating elements ( some of dont work properly - [presume this is the battery trying to conserve energy)

What I have had looked :p- 

• Battery - i have had a new one put in just over a week ago (light still coming on though) . I have a bosch one ( I dad have a napa number in which i got told were known were to be terrible). 
• Alternator - i have had this looked at 3 times in total and have been told by 2 separate garages that it is fine and does not need to be replaced . I think it was 13.5v.
• Starter motor - advised that this is fine.
• spark plugs - again told they are fine and do not need to replaced

i am at a loss as of what else i can do? Does anyone have any advice please?

Thank you :)

The alternator is not fine.  Those garages don't understand SmartCharge.  13.5v is the default value for when the SmartCharge isn't working.  The easiest test you can try first is unplugging the plug on the alternator, and then firmly re-plugging it again.  Though I suspect you'll have a damaged wire somewhere between that plug and the ECU or fusebox.  Need an auto-electrician I'm afraid, not a basic garage.

I agree with Tom. The alternator or the wiring is at fault. At 13.5 volt the alternator is running at it's default charge rate which it only does when the Smart charge system has failed.

Have a read of this thread of another Fiesta (2004 model) with charging problems. Just read from 23rd October onwards if you don't want to read the whole thread.

 

Thank you @TomsFocus and @unofix for the replies. 

Will take a look at the thread above and get the car in to an auto electrician 🙂

 

 

 

2 minutes ago, fordnumpty said:

Thank you @TomsFocus and @unofix for the replies. 

Will take a look at the thread above and get the car in to an auto electrician 🙂

 

 

 

Hi, let us know how you get on 👍

sorry another question - do i also need to get the alternator replaced? or should i take to the auto electrician place as a first port of call? 

30 minutes ago, fordnumpty said:

do i also need to get the alternator replaced?

Take to a good auto electrician. It is often a broken or corroded wire in the harness or plug that is at fault. If the alternator is broken then the auto electrician will most probably quote you to replace it.

Hi everyone, 

just wanted to update on the battery light situation - its been at an electical garage today and i needed a new wire, an alternator and a belt ( which is sat next to the alternator). Not sure if the belt is related to the problem i was facing but apparantly it was looking very worn out . 

Battery light did not flash on at all on the way home which i am really happy about . I am hoping that now these problems have been fixed the battery light stays off. 

Thank you to all for the advice :)

Hi again,

So after my post the other day the car is not fixed .

the day after the same issue with the battery light occurred only this time all the electrics went mad and the ABS /Stability thing , stereo all started going mad. It ended up with the car steering wheel freezing and the car making warning sounds .

i immediately rang the garage and they brought the car back in yesterday.  I have called to ask for an update and he has told me that the same fault is kicking up and that he has checked the wiring but can’t see any that looks to be damaged. 
 

He has said he has stripped the car back further and looked more in depth.  I really don’t know what else I can do or where else he could look? 
 

Ps - I think he has checked the pin in the plug? 🤔

Replace the alternator. That recent list of problems would say vehicle voltage was unstable and very low. If when checking the voltage it seems fine then I suspect you have an intermittent rectifier fault inside the alternator.

13 minutes ago, unofix said:

Replace the alternator. That recent list of problems would say vehicle voltage was unstable and very low. If when checking the voltage it seems fine then I suspect you have an intermittent rectifier fault inside the alternator.

The alternator was replaced on Tuesday. The same issue cropped up with the battery light and then after about 30 mins the othwr issues occurred. These had not presented previously - just the red battery light.

Edited November 17, 20232 yr by fordnumpty
Added more info

4 hours ago, fordnumpty said:

The alternator was replaced on Tuesday.

Sorry missed that when reading your post.

Now you're headed in to the world of faulty BCM and water ingress/corrosion of the connectors.