Battery light on dash never turns on

[SMFreak]

Hi, just bought Ford Fiesta 1.6TDCI Econetic, year 2012. Found out alternator is charging in so called default mode, it was easy through Forscan to see U0120 error saying PCM is not talking to aleternator. Violet wire (LIN signal) was somewhere broken in a loom and I made bypass taking the same LIN signal from BMS and from that moment DTC U0120 is cleared, now start/stop function and rear window heater is working as it was expected.
Wondering why battery light on dash does not come on once I turn ignition on before cranking? Usually as I know it should show up and once cranked in case everything is ok with charging it should dissapear.
Have never seen this battery light on dash as also for DTC U0120 MIL was turned off for this error (as written in this DTC desc)
How does this work on this car, EU model from Netherland, have seen this battery light under km needle which never turns on?
Even from Secret Dash mode test all lights turns on except battery light.
BTW charging is ok now, SOC and SOH on green, all functions are correct and no DTC at all.
Thanks

 

[Handy Andy]

Even from Secret Dash mode test all lights turns on except battery light.

This seems to be the cause, the light for it is either broken or blacked out.

​

Do you see this Icon?
​

Your vehicle may be Diesel (Netherlands) ECO-netic engines are shown to be Diesel powered - so the Charging system and the "Warm up" to start the Glo-plugs to make the Diesel fuel ignite when starting may change the look of your Pod Instrument Cluster.

The "HEC - Self-Test" mode is internal to the Pods Instrument cluster - so the test for the boards' internal heath shows no light for that Icon either. For if the test mode fails to light that light or it's masked to not be able to light that light, means that board fails the light (or Idiot Lamp test) - has to be fixed or repaired.

Some other potential causes:

• Battery Reset - The vehicle - due to it's features may have a Stop-Start system which requires the battery condition to be monitored - if the vehicle gets driven and is used in a lot of slo-traffic with a lot of stop and start action, the vehicle battery may fail - and a monitoring system that usually engages may light a light but may have been defeated or not properly set due to other conditions that have been cleared by performing a DTC code reset using a code scanner to clear another light (Check Engine or Cog Exclamation Light meaning Engine conditions) - which may have cleared the preceding level of codes leading up to this error - those codes leave a trail of bread crumbs to help with the repair - which are now cleared and so offer little in a way to trace the error back to the original condition.
  • A Battery Monitor system uses a relay on the GROUND wire - so it would be visible to see when you open the hood to check the engine and battery - you'd see what looks like a module on the NEGATIVE battery post with wires going to it - this disconnects the battery in a theft condition. And monitors charge condition it has, so it should set a light because of a monitoring system it has can detect and tell the PCM the battery needs charging or will require service soon.
• Secondary Battery failure - on many start-stop systems to help fuel efficiency and emissions, a secondary battery is also kept somewhere in the vehicle to power subsystems while the vehicle is stopped. If this battery fails it can also set a code but not illuminate a light or lites an unrecognizable symbol or even display a message showing a fault in the charging system but the DTC if it's been cleared, may not be stored - so if the LIN system can't seem to keep the battery charged, another battery in a Stop-Start feature may have failed and is not charging - preventing codes from being set due to the drain a failed shorted battery presents on the system
• Improper Battery Used in Replacement - Most vehicles pre-2010 used LEAD-ACID battery as standard in most vehicles, however the Activated Glass-Mat technology (AGM) was introduced and many automakers are switching over to this newer design for the battery technology lets the electrolyte and the plates recover their charges more quickly than using the older separator technology with materials similar to cardboard used for generations. They still use LEAD and ACID but the separator used in the battery (the dielectric between the plates) makes the battery able to recover more quickly.
  • Drawbacks in switching technology - requires any vehicle with an older changing system to be upgraded to detect and charge a vehicle using AGM technology versus the Standard Lead-Plate technology - a discharged AGM and Standard battery look similar to the Alternator and PCM but use the AGM in a non-AGM charging system can be overcharged and damaged by an older standard charging system and even damage the sensitive electronics in the vehicle causing even more costly repair of the damage.
    • Same can happen in a AGM charging system for the Standard battery can explode from the rapid overcharging the system can perform because the AGM versus Standard Pb battery have different charging rates and a vehicle programmed with AGM charging technology will destroy a Standard Lead-Acid battery very quickly and even destroy itself trying to charge it.

VERIFY This! - Check with a local Ford Dealer that knows your vehicle - if the ICON has been changed to a different symbol - this would put the warning light and the symbol for it - possibly in a different location - or someone could have damaged the dashboard from a previous repair.

 

[SMFreak]

Many thanks for valuable comments. I was thinking that this battery light on dash does not light due to this desc from DTC:
===PCM DTC U0120:00-2F===
Code: U0120 - Lost Communication With Starter/Generator Control Module

Status (-2F):
- DTC Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC

So MIL is off and that was ok for me but I was somehow sure once I resolve DTC U0120 what I did, battery MIL will come back. Once I resolved U0120 what I have noticed immediately is that charging voltage measured by Voltmeter on battery poles and from Forscan Live data shows now 14.8V, start stop started to work (previously 15sec after start it turns off and you cannot turn it on) and finally can use rear window heater (previously you can turn it on in first 15sec and it automatically turns off) which was expected under this conditions where PCM does not talk to Alternator regulator. Only battery light is missing.
What I have also noticed is that Secret menu battery voltage on dash shows 1V less than Voltmeter measurement on battery or Forscan Live data which are the same 14.8 comparing to dash 13.8.
Is there possibility through some programming or configuration of modules to permanently disable this battery light?
Below are pictures of my dash, BMS and battery.

Battery is OEM Ford for this car EFB battery good condition, proper SOC and SOH after DTC U0120 repair. No issues during cranking, start/stop works fine now.
BMS has 2 wires, violet is LIN and Yellow is 12V from +battery pole going through 3A fuse and this voltage comes to BMS connector.
BTW not sure how to reset BMS as from Forscan for my BCM I dont have this option, doing some other tricks by pressing buttons/flashlights etc does not show any results as I dont have battery light to see it flashing as confirmation for BMS reset.

 

[Handy Andy]

Have you replaced the Alternator?

The issue looks to be more of the LIN wire - either opened or is not talking to the Generator to develop resources and profile so the system can charge the battery correctly and it is charging the correct battery for the system.

The OEM did make it so that once the idealized versions of the charging system failed, it would have a default mode of what a typical charging system would do, being 13.8 to maybe 14.1 volts which is safe for the vehicle and the battery but not idealized for the system.

Which to ask - does your vehicle have a Stop-Start system when you drive it?- as in when you come to a stoplight or a complete stop or even coasting to a stop - the engine shuts off, then restarts?

Then you may have a reserve battery (not the sounder alarm one) that may be charging but the system is not using it - which raises the next question of a failed fuse or switchover relay designed to let the reserve battery hold the electronics up and working until you release the brakes and move forward from the stop so the engine needs reserve power to start to do this - and rt sounds like you have something there recognizing it. But if a fuse or a wire has been cut out - removing any access that system did think it once had, the start stop function quits and this may show under a more thorough DTC scanner check and this may make them think the Battery minder system has failed - it may not have, just there's nothing to tell it to monitor so it disables the function until the relay, wire or fault is fixed and keeps the light off until someone whom knows about the charging system then will look into it.

More Thorough DTC check?

• Yes, the Forscan can do a lot, but it will only check for Modules and subsystems it's programming is aware of to see their string ID's and know how to process them. If the BMS is of a hybridized or otherwise non-standardized form of charging it is not capable of recognizing it. (being that the vehicle is for use in the Netherlands and not USA) The Instrument cluster is storing this code but you don't have imminent failure of the charging system. Just subsystems or modules that are not detrimental to its emissions or other electical conditions - so something got masked - as in masked off. So a good DTC scanner can find these codes for the "U" versus "P" identifies this from a different sub-system - but it may still indicate repair for the module is unable to communicate back so the default messages appear even though everything seems ok.

 

[SMFreak]

Original alternator has been reworked since it was taken out from vehicle to replace regulator as I was looking for DTC U 0120 solution.
So alternator is the same but regulator is new.

Moreover LIN wire didn't have a connection to regulator and that was the culprit of this DTC. Once I made bypass to the same signal going to BMS, U0120 dissapered after clear, charging voltage raised from default to 14.8 and start stop started to work.
Yes start/stop works properly once I stop on traffic light engine shuts down indicating green start/stop light on dash, once clutch is pressed it cranks and starts easily.
No DTC from Forscan using OBD link MX+

BTW since the car is 2nd hand just imported who knows maybe somebody was too smart not resolving U0120 error but rather playing with cluster annoying battery indicator.
Will remove cluster and see what's inside.

Thanks for your comments and advice

 

[SMFreak]

Issue resolved. I suspected that somebody did some stupidity on cluster itself and there it is. He put silicone into the hole where battery led resides and completely glued and covered SMD LED.
It was hard to remove all silicone without damaging led itself, but I managed to do it carefully.

 

[Handy Andy]

Nice detective work - good job!

Sorry about that mess with the SMD LED getting glued - but know now that you've conquered the problem - thanks for sticking with it and keeping us in the loop!