Auto hold/Hill Start Assist Malfunction

[archie2000]

I have just got back from a countryside drive, during which I had to brake sharply in a country lane to avoid another car.

I immediately got a warning pop up to say that the Auto hold/Hill start assist has malfunctioned. 

I drove home OK, using the manual handbrake button when required, parked up on the drive and switched off.  I've tried switching auto hold back with the button, but it just triggers the error message again.

I was hoping that after doing a key cycle it might reset, but not so. Any suggestions from you learned lot as to whether this can be reset or do I need to take it to a dealership just because I braked hard!  Cheers.

[unofix]

Hi Paul. Is your car manual or automatic ?

Auto Hold and Hill Start are two different functions although they both work in a very similar way.

If the car battery is feeling a bit run down (as they often do these days) then Auto Hold can sometimes not be available. There is a chance that after the car has been parked up for an hour and you start it back up the problem will have reset. If not then disconnect the battery negative for 10 minutes and then reconnect. That will cause all modules to go through the wake-up handshake.

If that still does not sort the problem then you need to read the DTC codes which should give a reason for the malfunction.

[archie2000]

Hi Unofix, sorry, I should have said, it is manual.

I had been on a nice long drive, so hopefully the battery was well charged, however, I checked it and it was 12.4 with the car switched off and 14.6 running. I'll leave it an hour though before I disconnect the battery to see if it has reset itself. Is there anything else affected by disconnecting the battery that will require resetting?

It is definitely the auto hold at fault, although I did think that and hill Start assist were one and the same thing because the Ford manual seems to deal with them as one and the same. 

[unofix]

Hello Paul, disconnecting the battery should not cause too many other issues other than you might have to reprogramme the one-shot window open and close function.

Auto Hold, applies the front brakes only and will stay on until you try to drive off at which point it will release. The Hill Start will only hold the vehicle for 5 seconds after you take your foot off the brake and will then release. Most cars now seem to have Auto Hold in place of Hill Start.

[archie2000]

Hi Unofix, nope, none of the above worked. I went into the engineering menu to check the DTC codes, but there where none listed.

Looks like a trip to the dealership where I bought it.  Only picked it up 4 weeks ago and it still has 3 months original warranty on it too.

Thanks for responding 👍

[MasterTechTip]

Hopefully a ABS module update will rectify this, I've had a few that are similar and it worked for them

[unofix]

Hi Paul, sorry it didn't work. 😞

As Master Tech says a software update may be needed. 

[archie2000]

Well, despite the battery charge showing normal, I decided to give it a boost charge for a couple of hours this morning.

When the charger showed it as full, I started the car, no warning messages, and auto hold is back working as normal. Stop/start still not working though....

I did book the car in for checks, but that's not until 17th August. I'll keep the appointment for now and see how things go.

Incidentally, in the engineer menu, the battery level showed as 11.1v.  Is that worrying?

[unofix]

19 hours ago, unofix said:

If the car battery is feeling a bit run down (as they often do these days) then Auto Hold can sometimes not be available.

 

30 minutes ago, archie2000 said:

battery level showed as 11.1v.  Is that worrying?

Yes very worrying. Normal battery voltage measured at the terminals after standing all night should be a minimum 12.4V

With the engine running at a fast idle the battery terminal voltage should be a minimum of 13.6V

[archie2000]

1 hour ago, unofix said:

 

Yes very worrying. Normal battery voltage measured at the terminals after standing all night should be a minimum 12.4V

With the engine running at a fast idle the battery terminal voltage should be a minimum of 13.6V

This was in the engineer menu on the dashboard. The car was not running at the time.

Yesterday I was getting 12.4v engine off and 14.6v with the engine running. That was across the terminals.

In the engineers menu, I am getting 11.1v with the car off and 12.3v with the engine running at fast idle.

[MasterTechTip]

I'd measure it yourself just to make sure, the menu display may not be correct. The battery is not charging at 12.3 volts 

[VFR800]

Is your car a MK4?

My MK4 reports an issue with the auto hold about once every 2 months. Ignition cycle, has always sorted the issue.

The computers on the MK4 seem to sometimes have issues understanding one another at times, it's a design feature!!!

While we're at it.......does your STOP/START work?? 😉

My latest electrical gremlin was the other month. The volume nob stopped working. Could twist it and the volume display would come up on the screen, but the volume would never rise above 0. Ignition cycle didn't clear it. Left it overnight and guess what.....go on guess.....;-)

[archie2000]

Yes, it is a mk4 car.

I bought it 5 weeks ago from a Ford main dealer, and the stop/start has never worked. I did go to the service desk to book it in to get it sorted, but they just advised me to give it time for the battery to fully charge after a long drive and it will start working again! 

Well it hasn't! I fully charged the battery on Monday and that resolved the auto hold, but not the stop/start.

I had booked it in for next Wednesday, initially to look at the auto hold issue, but as that's OK now, I'll get them to look at at the stop/start issue.

Too much electronic functionality putting a strain on the battery is a worry!

[unofix]

Hi Paul, you need to learn to live with the fact that Start/Stop doesn't work. It can never be fixed, the best that anyone could do is get it working for a few weeks before it will stop working again.

There are hundreds of people just on this one forum all saying the S/S system isn't working. New batteries are being fitted right, left, and centre as if they grow on trees and are bio-degradable when finished with. The hundreds of miles cars are doing back and forward to the garage to get S/S "fixed" far outweighs any possible benifit. The one positive thing about when we are all forced to drive EV's is that the failure of S/S will be finally put to bed and automotive history will quietly forget about it.

[archie2000]

Hi Unofix, to be honest, I know that I would probably end up switching it off after a few days, as I am aware of other drivers experiences with it.  Its just that I am of the opinion that if a feature is included on a car, it should be operational whether it is useful or not! 😅

 

[mjt]

16 hours ago, archie2000 said:

Too much electronic functionality putting a strain on the battery is a worry!

The problems are mainly caused by the fact the BMS is programmed never to charge the battery above 80% full capacity. Then the other systems like Auto-Hold and Stop-Start seem to be programmed to stop working if the battery capacity is much below this. On the face of it you'd think this would be a simple thing to fix if the various teams could just get their heads together.

There seem to have been more complaints about this since the Mk4 came out.

[TomsFocus]

1 minute ago, mjt said:

On the face of it you'd think this would be a simple thing to fix if the various teams could just get their heads together.

If the customers could contact the electronic design teams directly I'm sure stuff like this could be sorted.  The problem is trying to get through 'customer services' and either hitting brick walls or ending up with Chinese Whispers...

I've had the same issue with my new fridge...it just needs a simple electronic alteration to chill the fridge section down to 'minimum' before starting the freezer auto-defrost.  When this happens randomly it stays nice and cool.  But other times it'll just be on the cusp of the compressor kicking in before it starts the hour long defrost procedure, so it warms up to unsafe levels.  I just wanted to know if there was any practical reason for this design, and to offer advice to improve future models.  But it's impossible to get any technical information from them or get through to anyone useful.  All they say is they can send an engineer out if it's broken. 🤦‍♂️  I can only assume this is the reason that Ford keep churning out cars with the same common faults year after year as well...  (Also had issues with VW CS this week as well, so not just Ford lol)

[Eric Bloodaxe]

2 hours ago, mjt said:

The problems are mainly caused by the fact the BMS is programmed never to charge the battery above 80% full capacity. Then the other systems like Auto-Hold and Stop-Start seem to be programmed to stop working if the battery capacity is much below this. 

My understanding is that both these measures are intended to reduce emissions. In the case of the battery, it is assumed that the other 20% will be achieved via regen when braking etc, reducing CO2. As many of us have found, this only happens if you have a suitable pattern of usage, even more of an issue over the last 18 months or so because of changes to driving patterns during Covid.

Stop-start of course is then affected in turn by the battery condition issues.

The cynical amongst us may of course believe that these things really exist to lower emission figures during official test cycles, rather than in real world driving, anyway😀, though stop-start could be useful in the case of those who would otherwise sit outside a school, etc, with the engine idling.

[unofix]

4 hours ago, Eric Bloodaxe said:

The cynical amongst us may of course believe that these things really exist to lower emission figures during official test cycles, rather than in real world driving, anyway

Roger !!! the very thought never crossed my mind 🤣🤣🤣

[Eric Bloodaxe]

Just now, unofix said:

Roger !!! the very thought never crossed my mind 🤣🤣🤣

Lol, me neither!😀

[GoHaveSomeFun]

On 8/7/2021 at 12:15 PM, mjt said:

The problems are mainly caused by the fact the BMS is programmed never to charge the battery above 80% full capacity. Then the other systems like Auto-Hold and Stop-Start seem to be programmed to stop working if the battery capacity is much below this. On the face of it you'd think this would be a simple thing to fix if the various teams could just get their heads together.

There seem to have been more complaints about this since the Mk4 came out.

The biggest problems look like after market front sensors fitted by the dealers, they look on quick inspection to be leaking backward voltage to the parking switch... I cannot see why they wire it it like this, as it's just wrong in so many ways, on another note, it may also be to much resistance on the negative side of things where the current is balanced rather than flowing in the correct polarity ... This I'm going to investigate... I'll post back with my updates soon

[GoHaveSomeFun]

On 2/27/2023 at 12:42 PM, GoHaveSomeFun said:

The biggest problems look like after market front sensors fitted by the dealers, they look on quick inspection to be leaking backward voltage to the parking switch... I cannot see why they wire it it like this, as it's just wrong in so many ways, on another note, it may also be to much resistance on the negative side of things where the current is balanced rather than flowing in the correct polarity ... This I'm going to investigate... I'll post back with my updates soon

I did check these although on the high side it's below 1mg ohm so ok I guess ... But I think it's more how you should use the cars, do the exact opposite of what they tell you... So use more electric devices such as the heater and front lights and they will take power from the battery at start up, causing the BMS to put more charge into the battery the amount of flow (current) will be much more than if these items where turned off, admittedly it will stress the engine more on start up for a mere couple of seconds... But remember that whoever designed the system allowed for 20% to be taken directly out of the alternator, not the battery... Stupid I know... But without properly loading up the battery on start up it will cause issues with a battery that's only 1% out of tolerance... Yes ***** stupid but just leaving the internal cabin heater on will resolve the issue... Without further intervention...