Mk8 Keyless entry fobs dont lock/unlock car after main battery went flat, yet key presence is acknowledged and car starts.

[slater]

Hi All,

I've searched both this forum and google and I've found lots of "almost" helpful info but nothing conclusive for my issue!

My elderly neighbour has a 2017 titanium petrol Mk8 fiesta. She has always had an issue with a parasitic drain on her main car battery and it runs dead if not started for a week or two.

She is away staying at a relations house over Christmas, and this morning called me to ask if I would travel across town to come help her get it started after the battery ran flat over Christmas and so I headed over with my portable boost pack starter expecting a 5 minute solution! The key fob obviously wouldn't work to get into the car as the battery was dead, so I got in using the concealed key in the key less fob. This was fine and within minutes the boost pack was attached and the car was started.

After running for 45 minutes to get some juice in the battery, we shut the engine off, got out and attempted to lock using the fob button. Nothing happened when we pressed lock/unlock etc. When I lock using the concealed Key everything activates in the central locking and wing mirrors close, so car battery has sufficient charge it seems, but nothing happens via either fob. Fobs have new batteries.

I found a website suggesting re-programming/resetting might be needed and sharing a procedure (see link), but this guide implied having one fob working to be able to reprogram the not working one. Right now neither key works to unlock or lock the doors. I also note that the keyless system acknowledges the key's presence in the cabin and lets one start the car, but lock functions aren't happening. I'm back home so can't test anything on the car this moment but looking at possible solutions online so posting here felt like i may get some experts who have seen this before!

Has anybody experienced this and does anyone have any advice on this problem. I would really love to help her out given she isn't likely to get any help from ford before Tuesday!

 

many thanks in advance!

 

[CharlieDene]

I have only had my MK8 with keyless start for two weeks so unable to help on the reprogramming of the key, however, did complete a software update on the car which was available if the car is hooked into a hotspot or home Wi-Fi. Took about 45 minutes. That might stop the parasitic drain on the car. Be patient and have the car idling the whole time. 

Her battery monitoring system might need a reset

Reset battery monitoring system

Found the method to reset the battery monitoring system on the Fiesta MK8.

1. Turn on ignition (not engine)

2. Ensure headlights are set to on

3. flash the high beam five times

4. press the brake pedal 3 times

5. wait for the battery light to flash on the dash.

6. Turn off then restart.

[CharlieDene]

8 minutes ago, CharlieDene said:

I have only had my MK8 with keyless start for two weeks so unable to help on the reprogramming of the key, however, did complete a software update on the car which was available if the car is hooked into a hotspot or home Wi-Fi. Took about 45 minutes. That might stop the parasitic drain on the car. Be patient and have the car idling the whole time. 

Her battery monitoring system might need a reset

Reset battery monitoring system

Found the method to reset the battery monitoring system on the Fiesta MK8.

1. Turn on ignition (not engine)

2. Ensure headlights are set to on

3. flash the high beam five times

4. press the brake pedal 3 times

5. wait for the battery light to flash on the dash.

6. Turn off then restart.

The manual states that remote control of locking is deactivated if car left for several weeks. Unlocking and starting the vehicle should have reactivated remote locking. I would proceed with any software update to hope a fix is contained within that update. I was prompted to do the update on mine after the radio would turn on randomly and other software glitches. All gone after the update.

[unofix]

54 minutes ago, CharlieDene said:

Reset battery monitoring system

NO !

The battery monitoring system is only ever intended to be reset when a new battery has been installed.

The inoperative keyless entry is caused by the car deliberately turning off the function because the state of battery charge is 70% or less.

Charge the battery overnight to ensure that it has a charge of 80% or more. Ideally 95% or better. Then in order to get the keyless system operating again, take the car on a short 15 minute drive and it will reactivate.

Resetting the BMS serves to do only two things. One it resets the 'Days In Service' counter so that the age of the battery can be determined. Two when used incorrectly it erases the stored information regarding the SOC. This causes the Body Control Module to reactivate everything it switched off because of the low state of battery charge.

[unofix]

Also when charging the battery (which should be done while still connected on the car) make sure the positive lead of the charger is connected directly to the battery positive terminal. The negative lead must be connected to the chassis earth point and NOT to the battery negative terminal.

[Aldridge Andy]

Might also be worth replacing the key fob battery with a good brand such as Duracell, Energiser, Panasonic, Varta as these keyfobs don’t tend to like the cheaper brands for some reason. 

[CharlieDene]

Thanks for the update, unofix. Appreciated. 

[Eric Bloodaxe]

Don't know if you've had time to look at the many low battery related threads on the Fiesta Mk 8/Focus Mk 4, Rich?

Just to emphasise the advice from @unofix the battery needs to be checked regularly (see chart) and given a proper charge using a modern "smart" charger such as C-tek, Noco, or Maypole.

You really can't rely on the cars charging system if the car is used infrequently and/or left undriven for a couple of weeks. If I'm away and not using the car for some time I've now got into the habit of putting it on charge before I even use it.

Low battery charge can cause all types of "weirdness" such as you describe.

Also to add to Andy's advice on key fob batteries - these should be tested before installation and show at least 3.3v. 

Beware of Duracell - there is evidence emerging of counterfeits entering the legitimate supply chain. Also, genuine Duracell have an unpleasant tasting coating to hopefully prevent children putting them in their mouth. They have a warning sticker on the battery and it is essential to ensure any residue is thoroughly removed before installation.

 

 

 

 

[slater]

Oh my, thank you everyone! I thought i had email alerts set to let me know if replies came in on here. I really REALLY appreciate everyone contributing here and all the advice above, what a great community! Thank you!

I took drove the car for her for a bit, and eventually followed the procedure I linked to above again with the keys located in the cut-out in front of the gear stick and it started working. Now I can't guarantee that this was the solution. Perhaps I put in enough juice driving the car that it started working of it's own accord and I simply thought I had solved it.

Either way, it is back working again and appreciate everyone's time here.

 

This parasitic drain, which I've done so much reading on. Some say it's a software update will resolve but other solutions or observations are made. I wonder if plugging one of those low power solar panels into the 12v in the car would keep it topped up, or whether this 12V supply is even active when the ignition is off. Has anyone any experience here? heading to change my settings so I see the replies this time!

 

Thank you all again.

[anon]

It won't do any harm. The Mk 8 has a lot going on even when it is inert. It drains batteries. Used daily for a good twenty miles, the stop start works, as does everything else. Left for a week and you would think it had contracted every computer virus known to man. The advice about charging the battery is most important. Your friend would be well advised to buy an intelligent charger (about £30) and if it is charged weekly with the negative connected to the body earth, then it will be fine. What is this mumbo-jumbo about  connecting the negative to the body?

The lead from the battery to the body contains a sensor which is used to monitor the energy flow into and out of the battery. If the battery is charged in the conventional sense then the computer program that monitors this isn't activated so it doesn't know that it has been charged. The battery is in fact only partially charged when "full" because that extends the battery life. I have had perfectly good results from two Fiestae with five year old batteries, so the method clearly works.

NB: Lidl have a charger on offer for £14.99 this week that will suit the Fiesta nicely.

[aot871]

On 12/31/2022 at 6:40 PM, unofix said:

Also when charging the battery (which should be done while still connected on the car) make sure the positive lead of the charger is connected directly to the battery positive terminal. The negative lead must be connected to the chassis earth point and NOT to the battery negative terminal.

Where is the chassis earth point  or can u just connect the negative  to any body panel  ?

[unofix]

Chassis Main Earth Point.

[DaveT70]

The source of the battery drain needs to be investigated and cured as it will only cause more problems later on