Hi all,

My first post here so apologies if I missed something. I first posted on the US forum, before realising there is a UK-specific one.

I'll go a bit in detail, but TLDR is also availble below.

I picked up a new to me Ford Focus MK3 (Titanium, 2012 1.6 125bhp engine) not so long ago.
The car had the random stalling issue, which is discusssed in great detail on this forum. I took the car to a Ford dealership for a PCM update to solve the stalling issue (it worked!), but after the PCM update the battery warning light came on.

The battery light now comes on (and stays on) every time I start the car after about 20-30 seconds.

The dealership that did the PCM update took the car for an inspection, but they couldn't find the root cause of the issue.
They checked the PCM <-> Alternator wiring, LIN bus and did a load test to no avail so they escalated to their own technicians.

The dealership is now suggeting to try and replace an alternator, but they're not sure this is the root cause of the issue.

The stats that I have:

• battery voltage on cold start is between 11.8-12.5 (depending on how long the car sat)
• battery voltage when the car is running: 13.5 - 13.7 (the former is from the TEST menu, the latter is from the OBD and also measured directly)
• charging system test (battery terminals measurment): 13.81 no load, 13.74 full load
• cranking voltage: 11.33, lowest drop 8.73
• battery health test: 443 out of 620 CCA

I also pulled the followind DTC codes from the car: U012D, U0010. I looked at the battery terminals + BMS sensor, and visually everything looks ok.

TLDR: voltage looks OK albeit on a lower side, battery light is on. What could possibly be the issue? I should also say the car starts and drives without any issues. I did over 300 miles since the issues appeared

Thank you all

I would be tempted to Ring Ford technical helpline. If it still exists

Explain PCM was updated from (??) to (??) by a dealer due to stalling issue and now battery light is on, they may know the fix/issue

Be aware Ford technical helpline is premium rate, about £2 per minute 0906 553 3447

Have your VIN to hand

Thanks Dave, I'll look into this! 
How can I go about finding out the PCM version? I was not told anything like that by the dealership guys.
Would the tech support be able to locate it from their end perhaps?

1 hour ago, yeetyeet1231 said:

battery voltage when the car is running: 13.5 - 13.7

That charging voltage with the engine running is low. The least that you would expect it to be would be 13.9V and up to 14.7V

This is in my opinion unlikely to related to the PCM update but perhaps it is.

I'd be removing the small connector on the side (sometimes back) of the alternator and checking the connectors very carefully for any signs of corrosion. Give the wires a bit of a tug, there are cases of the wires having broken 10 to 15mm back from the connector.

With the plug removed from the alternator and the engine running at a fast idle you should get a charging voltage of 13.95V which is the default emergency value when the smart charge system is not connected.

40 minutes ago, yeetyeet1231 said:

Would the tech support be able to locate it from their end perhaps?

Yes

1 hour ago, unofix said:

I'd be removing the small connector on the side (sometimes back) of the alternator and checking the connectors very carefully for any signs of corrosion. Give the wires a bit of a tug, there are cases of the wires having broken 10 to 15mm back from the connector.

Thank you, this sounds like an easy thing to try. Are there any tips on how to disconnect the plug? There's little room to wiggle, but pressing on the side of it doesn't seem to work - it feels like a solid piece 

 

1 hour ago, unofix said:

That charging voltage with the engine running is low. The least that you would expect it to be would be 13.9V and up to 14.7V

Thanks for this, I've not seen the voltage go above 13.8 

Figured this dead thread is overdue an update, just in case someone stumbles upon it. 
 

Ended up replacing the alternator and the warning light is now gone. 
 

The new alternator is charging at around 14.9V most of the time. Not too sure if it’s a sign of more problem or just a dying battery. 

14 hours ago, yeetyeet1231 said:

just a dying battery. 

👍