How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Matt Your Own Question
Matt, Engineer
Category: Ford
Satisfied Customers: 20373
Experience:  BEng hons Mech engineering, in auto industry 22 years
Type Your Ford Question Here...
Matt is online now
A new question is answered every 9 seconds

2014 Ford Focus ST Battery light on Codes U012D and U0284 I

Customer Question

2014 Ford Focus ST
Battery light on
Codes U012D and U0284
I have the service manual. I followed all the diagnostic instructions. No result. I replaced the main engine harness and the alternator. The problem is still there. On one of the Internet forums i found a reference to TSB 11-07-13 but i could not find anything in Mitchell1. Is there TSB regarding this issue? if not, what could be the problem? i don't have a spare PCM and even if I did i have no way to program it the key, so please don't suggest that.
Submitted: 2 months ago.
Category: Ford
Expert:  Matt replied 2 months ago.


1st check that the alternator is actually charging the battery in the car by taking a battery voltage reading with the engine off then another with the engine running. The 2nd reading should be higher than the 1st and climbing steadily. And also check that the alternator is secure to the engine as this provides the ground for the charging circuit and make sure that the engine / gearbox earth strap is secure and the contacts are clean and bright.

if the alternator appears not to be working - take it to a electrical specialist and ask them to test it as sometimes you can replace just the diode pack and this will repair the alternator without requiring replacement

And one last thing is – how old is the battery? – As even good quality ones need replacing every 5 years and faulty battery just won’t hold a charge

Customer: replied 2 months ago.
Matt,It is not obvious to me that you read my question. Please do. Copy-Paste answers smell really bad.Thank you.
Expert:  Matt replied 2 months ago.


OK so

U012D - LIN Generator No Communication
U0284 - AGS Loss of Communication

both of these point to an issue with the 'smart' alternator not talking to the ECU / Body controller

modern units are switched to charge with a CAN signal and Ford prefer the use of a Silver calcium type battery for their charge management so I'd check that 1st

There is a TSB 11-07-13 that shows up as

11-07-13 - BATTERY LIGHT ON - DTCS MAY ALSO BE PRESENT U012D, U0140, B11DB, U0422, P2610, P06B8 OR U0257

but this is for the 2012 Focus? and not the ST

Also there was a recall '14S17' regarding Focus ST engine wiring harness issues but as you've already replaced the harness then this should be rectified

so if the battery is correct then I'd ask Ford to do a communication test between the ECU and alternator to check that the ECU isn't faulty

Customer: replied 2 months ago.
Matt,The battery is 1.Correct and 2. New. As i said i have the OEM service manual and I am very familiar with it. if you review the wiring diagram in question you will see that there is only one "info" connection between the PCM and the alternator. It is part of the harness i replaced. The communication test you are referring to will ask the PCM to ping the Alternator at which point the PCM will respond "Dude, how many times do i need to tell you the same thing.I can not reach it"Matt, I am here because i looking for somebody with experience in the area i have problem in. If you can suggest something i have not tried, please do. Your suggestion to go to a dealer is not worth $42. Do you have other ideas?
Expert:  Matt replied 2 months ago.


fair enough I'll opt out and open this back up to other experts

good luck