Ford Fiesta - Fiesta MK7 battery light issue - 4x4monster

My 2011 fiesta 1.25 has an annoying problem where the battery light keeps coming on, mostly on longer drives. it's been like this for a while but the car has always been fine apart from the light. While driving at the weekend the light came on again but this time more lights came on and the car started to drive weird (power steering and ABS stopped working) Stopped the car and turned it off, when trying to restart the battery was flat.

I have had this happen before in a previous car so I assumed it was a faulty alternator. after jump starting the car everything worked fine again and the battery light was off. I checked the alternator output and was getting 14.5v with the car at idle. I thought it must have an intermittent fault so I got the alternator changed yesterday. Driving to work again this morning the light has come back on so it's not the alternator.

If anyone has any idea what could be wrong, I would be grateful for any help.

Ford Fiesta - Fiesta MK7 battery light issue - RobJP

I think the battery is probably dying. Just because the alternator will send charge to it, doesn't mean the battery will hold charge.

A battery that is on it's way out can come up with other spurious faults too - more lights on, ABS and PS stopping working would seem to fit in with that too.

Ford Fiesta - Fiesta MK7 battery light issue - elekie&a/c doctor
As above,make sure the battery is up to scratch and the correct calcium type fitted to cope with the smart charge system.Also check the 3 pin connector at the alternator .make sure the pins are clean and tight with no corrosion.
Ford Fiesta - Fiesta MK7 battery light issue - 4x4monster

Hi, thanks for the help. Ill get the battery checked and changed if it needs it. My alternator only had a 1 pin connector on it, i have already checked this and it looks fine. Do all fiestas have a smart charge system?

Ford Fiesta - Fiesta MK7 battery light issue - Peter D

Only one connection. Are you sure, absolutely sure. Regards Peter

Ford Fiesta - Fiesta MK7 battery light issue - Peter.N.

If the battery is OK, connect a voltmeter to the cigar lighter so you can monitor it when you are driving in case the fault is intermittent.

As Peter D suggests there should be at least two connections on your alternator, the large terminal with the thick lead to the battery and a thinner one that goes to the warning light.

Ford Fiesta - Fiesta MK7 battery light issue - elekie&a/c doctor

If this is the later smart charge system,then there will be 2 wires at the alternator.The main thick power feed supply and a thin logic wire that runs back to the engine control module.There is no wire that runs directly to the battery charge warning light.

Ford Fiesta - Fiesta MK7 battery light issue - Peter.N.

Right - to modern for me.

Ford Fiesta - Fiesta MK7 battery light issue - 4x4monster

Update. Had battery checked and was told it was faulty I replaced the battery and still no change. The alternator has the main thick cable and a second small plug with a single thin wire. I thought smart charge had a plug with 3 cables not only 1?

Ford Fiesta - Fiesta MK7 battery light issue - 4x4monster

Update. Had battery checked and was told it was faulty I replaced the battery and still no change. The alternator has the main thick cable and a second small plug with a single thin wire. I thought smart charge had a plug with 3 cables not only 1?

Ford Fiesta - Fiesta MK7 battery light issue - elekie&a/c doctor

Ford no longer use the 3 wire smart alternator system .Current models use a 1 wire logic control but still a smart charge circuit.

Ford Fiesta - Fiesta MK7 battery light issue - 4x4monster

Thanks for clearing that up, I'll need to get it in somewhere, its beyond me at this point.

Ford Fiesta - Fiesta MK7 battery light issue - JohnnyB08

Hi mate, did you ever get to the bottom of this problem? I've having exactly the same issue! Would be really grateful for an update on how you got on. Many thanks!

Ford Fiesta - Fiesta MK7 battery light issue - Frankie99
Same question JohnnyB08 - I have this exact issue and 3 garages have failed to find the problem - had new alternator new battery and new wiring from alternator to the battery and still the battery light comes on intermittently - car still drives OK
Ford Fiesta - Fiesta MK7 battery light issue - John lucking

Same issue I have replaced the alternator had a new battery fitted.and had the smart charge wire replaced..and still the battery light comes on.any ideas ty

Ford Fiesta - Fiesta MK7 battery light issue - Ricky Henderson
Did anyone ever get to the bottom of this issue as i am now experiencing same problem, both battery and alternator checked out ok uner load and idle ?
Ford Fiesta - Fiesta MK7 battery light issue - steve650

Fault fixed!!

Our 2012 Fiesta 1.25 has had an intermittent battery light fault for a couple of years. I hate intermittent faults - every time I checked the battery charging voltage it was OK. Finally this month the light stayed on during a longish trip and the battery went flat. The alternator was not showing any output. I changed it for a secondhand one and the problem has gone! I stripped the old alternator to see what had gone wrong after only 40k miles. I found copper strands in the brushes/ slip ring area, presumably peeled off the slip rings. I think they were occasionally shorting out the rings, then clearing off until the next time. The brushes were OK, although there was a wear slight groove on one slip ring. I fitted new brushes and cleaned the slip rings, so I have a spare on the shelf, just in case! You can check the brushes fairly easily - if you ignore the pain of removing the belt to get the alternator off. It might be possible to do it in situ, but there is not a lot of space down there.

I doubt this is the answer to most of the faults listed above, but may be worth checking. Good Luck!

 

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