FOCUS Mk4 - STOP START NOT WORKING OR IS IT?

In this video we shall be diagnosing and fixing a Mk4 Ford Focus. The vehicle's stop start system was not working despite the green light showing that it was activated. Follow the video to see just how much information is available to successfully diagnose and fix this system.
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[@SYDiagnostics]

It's been brought to my attention that the green light is for auto hold, which when reviewing the footage, it is. I've made an error on that behalf as my own Mk4 focus has a different dash. Anyhow, I was thinking of removing the video for this error, but as it was a fix, then I've decided to keep it up

[@loshtaylor]

Good decision. We all make errors and I make more than most..

[@simonbaker9983]

Still a really useful video, many thanks. I’m thinking of replacing the EFB battery in my MK4 focus with an AGM one to try and improve start stop performance as my EFB regularly falls below the 80% charge threshold. Could you possibly do a video on upgrading EFB’s to AGM please or offer some advice? Many thanks, Simon

[@simonbaker9983]

Still a really useful video, many thanks. I’m thinking of replacing the EFB battery in my MK4 focus with an AGM one to try and improve start stop performance as my EFB regularly falls below the 80% charge threshold. Could you possibly do a video on upgrading EFB’s to AGM please or offer some advice? Many thanks, Simon

[@SYDiagnostics]

@@simonbaker9983 All I can think you'd have to do is go into the BCM settings in Forscan and hope the battery type is in the drop down menu, then change it accordingly. That way the energy management system can monitor accordingly. Then re-set the BMS. 75% is the threshold. Quite often if you disconnect the BMS connector, remove and clean the negative terminal and leave off for 5 mins minimum and re-connect, all is restored

[@simonbaker9983]

@@SYDiagnostics brilliant, many thanks, I’ll try that first. Thanks very much for your advice.

[@mikeberry304]

Nice one Steve , great fix without the parts cannon that most would do , top job happy customer 👍👍👍👍

[@abdulh9687]

Great video. Its been a while hope everything is okay. I've never had a customer complain about start stop until all this fuel crisis began....

[@InvisageStudios]

Thanks for this! I'm trying to get mine to work on my Ford Transit Custom after the battery dropping too low. Even after fully charging it - Auto SS doesnt work. I'll take it to my dealership and ask them to do a BCM reset. Thanks for this!

[@cagiva125cc]

You just saved us with your video, many thanks

[@AM-sg4by]

Just FYI, the A in the green circle is not related to the stop start system. That is the Auto Hold function which allows you to take your foot off of the brake pedal when you come to a stop in gear but still remain stationary. Great video though.

[@SYDiagnostics]

Thanks, it was brought to my attention just as I read your comment. My bad. The dash on my own Mk4 Focus is different and upon looking back at the video you are 100% correct.

[@AM-sg4by]

@@SYDiagnostics it’s all good. Great vids though. Keep doing what you’re doing.

[@chadcoy775]

I got beaten to the punch ,was going to say the same about the auto hold indicator, but it's good the video was left up as it shows we are all human and can make mistakes. SY Diagnostics you are doing a great job keep it up 👍

[@Sarah-im5ud]

Awesome fix , wish there were a solution or manipulation we coukd do on our own without the software

[@chekelley6861]

Really interesting. I learned a few things here!

[@johncook7864]

Excellent report on stop start as they are such a pain sometimes with so many pids reliant on the operation , but that 4 scan is excellent for showing all pids where as FDRS is not so good in my opinion, funny part when you said about the green stop/start light and I said to my self , mmmmm I’m sure that’s for auto break hold , and be hold the comments after said that 😁 but with your excellent knowledge I was sure you new that anyway. Another good video though SY , keep them coming 👍👍

[@SYDiagnostics]

I must admit i'd made a mistake and mistook the autohold for the stop start. Even more confusing because my own Focus Mk4 has the auto hold and stop start lights in different places and mine says "auto hold" rather than a symbol

[@loshtaylor]

My 1.5d Active X has been doing this since I bought it (new). It has been back to the dealer at least 5 times with this issue and a knocking from the sunroof. The sunroof was eventually fixed (for now) but the stop-start is still intermittent. I did read elsewhere that this issue was down to the battery management and informed the dealer, but no joy in getting it permanently fixed. There are a number of methods to reset the battery management system without any tools. Supposably If everything goes OK the battery light will flash 3 times on the cluster within 15 seconds of doing the actions. I have tried many of these and have got the battery light to flash 3 times. Sometimes it works, but it does not last long. In the end, I have given up on this tech it is crap, and as such emissions quoted can not be achieved. If I'm in a queue I just turn the engine off. Just a minor error in the video. The green indicator at the top of the dash is not an indicator for a stop-start as stated. It is the hill assist breaking which is turned on. This is independent of the stop-start. If anyone has a real long-lasting fix I would like to know. e.g turn off all of the sensors maybe, but I know it's a spider web of interconnectivity.

[@simonbaker9983]

Hi Lawrence, have exactly the same issues and am considering trying an upgrade to an AGM battery. By the way what was the fix for the sunroof as I have that issue too? Many thanks, Simon

[@loshtaylor]

@@simonbaker9983 They removed the headlining and then stuck an anti-rattle tape on the sunroof runners and lubricated the sunroof rubbers. I still think that it is due to the expansion and contraction of the sunroof glass to the frame and lubricating the rubbers allows the glass to move freely. I don't expect it to last very long. I hope I'm proved wrong.

[@simonbaker9983]

@@loshtaylor thanks Lawrence, I’ll get the dealer to do that to mine too. Cheers

[@cyberpope2137]

AFAIK the BMS (battery management sensor) for early model year mk4 focus has a factory defect, newer ones have an updated part that works correctly

[@robthomas7232]

Well that's handy to know. I hate stop start though as it always manages to kick in just as I'm about to accelerate onto a roundabout or at a junction.

[@mark-1rc502]

Freaking marvellous 😅 I wish you were near London

[@CARRJ142]

Another great video.😎

[@marion1600]

Well done! Was the battery replaced earlier on this vehicle or why the bcm needed to be reset?

[@SYDiagnostics]

Battery showing 509 days which is younger than the car. I see lots of mk4 focus stop start issues. Most cured by re calibrating (not re setting) the bms due to low state of charge figurez. Starting to see a pattern where this doesn't fix it when the SOC is good and no other inhibitors, but a reset will resume function.

[@sitdox]

Great diag as always All the best

[@the_retired_mechanic]

Steve do you think this would be possible to diagnose with machines like snap on and autel or will people have to have forscan to fix these ford's with faults like this?

[@kennedysgarage3281]

Very good question, I like it 🤔

[@SYDiagnostics]

You'd have to see what data the snap on etc show. I'd imagine they would be the same as they are just all back engineered

[@jackc7084]

Great job!

[@bogdanmihaila4885]

Hai there. A move how to replace accumulator from engine, please? Ford focus Mk4 2019, 1.5 A8

[@mark-1rc502]

I check my Battery voltage it’s 12.5 v and about 14.8volts with engine running , but my Start Stop doesn’t work, it used too but suddenly stopped. 😢 but I always get the Grey A with the line through , every time I stop the Information system says Engine charging . When I drive it says Normal operation . But the engine no longer stops

[@SYDiagnostics]

What is the stats of charge of the battery as shown in the video

[@adamfarmiloe]

The battery BAT_CURRENT you said was erratic, what does a normal healthy pid look like? Mine seems to go to zero rather fast 🤔 and battery remains around the 69% mark

[@glooo7193]

I've got a 2017 focus mk3.5 1.5tdci question, my start stop is not working, not to bothered about that. But my aircon also stopped and I was wondering if that could be something to do with the battery?. If I turn the engine off, within about 5 mins I get a message saying system shutting down to save battery. Thanks in advance for any information anyone can give me

[@SYDiagnostics]

Stop start most likely will be battery. The AC could be multiple things (ac gas pressure, compressor, compressorclutch, outside air temp sensor etc). I've only known the battery state of charge affect the Mk4 focus mild hybrid AC system. Not the earlier o

[@tlaf4367]

How can I get this to work on my focus please or do I have to take it to a main dealer.

[@stuartconnell5873]

That green light on the top of the dashboard is not stop/start indicator it is the braking auto hold system.

[@SYDiagnostics]

Yes I publicly admitted it and at the time I was going to remove the video. I got confused as on my focus of a similar age the light is elsewhere. Thanks for watching

[@JamesAllen300]

Hi. left a question on here for my 2010 focus but it seems to have disappeared. I don't know if you are using Facebook as the last post was in 2019.

[@SYDiagnostics]

What was your question?. I tend to only use facebook to announce a new video and dont enter into discussions there, nor offer technical support via email otherwise i'd be bombarded. The channel is just a hobby for me

[@JamesAllen300]

@@SYDiagnostics My question was I'm trying to code a JER113 power steering motor accessible via passenger side wheel arch for a 2010 focus 1.6 tdci. Can I copy the as built data and copy it across to the new unit?

[@SYDiagnostics]

@@JamesAllen300 I can't see why not. I've done more on VAG with this system than ford. But it's usually just simple coding rather than programming

[@sleepyb0ye269]

All this doagnostic can be done with the cheap £25 forscan usb plug?

[@SYDiagnostics]

Correct

[@sleepyb0ye269]

@@SYDiagnostics does it not require a paid license to access the service features etc? i'm finding some mixed information online so would love if you could clear up

[@SYDiagnostics]

@@sleepyb0ye269 the licence is about £12 for 1 year if I remember. That will open the whole program and allow all functions. The functions and capabilities differ on vehicles and ages. No immobiliser work can be done from around 2010 model year. The newer the car the less functionality, but that's because most manufacturers use online services nowadays

[@sleepyb0ye269]

@@SYDiagnostics Okay thats great, thank you

[@GameWithViiP3R]

Ive had this charged the battery to full reset the bms reset the bcm and still it doesnt want to work any other ideas ?

[@SYDiagnostics]

What is the state of charge of the battery as shown in the bcm? You can also view the stop start inhibitors to see if anything is stopping the function

[@GameWithViiP3R]

@SYDiagnostics hiya mate battery charge is 100%, and i reset the bms, and it is still not working. I've reset the bcm. The battery is fine as its a 2 year old batter

[@dank2532]

Cheers mate so if I disconnect the battery will it have the same results?

[@SYDiagnostics]

Of your stop start isn't working you need to know what the state of charge is as reported by bcm. If you can't access that. Then I'd disconnect the battery monitor and fully charge the battery. Reconnect and then see how it reacts... It won't be instant and could take a few miles

[@dank2532]

@@SYDiagnostics ok thanks I’ll try it 👍🏼

[@theo3995]

Why people dont switch off for ever with forscan?

[@GameWithViiP3R]

My cmax stop start doing this charged the battery reset the bms if i disconnect the battery and re connect will that reset the bcm

[@SYDiagnostics]

Yes. Disconnect for 5 mins at least

[@GameWithViiP3R]

@@SYDiagnostics and will everything work as i left it its a lease car and i dont want to mess it up ford want £75 just too look at it

[@GameWithViiP3R]

Once i disconnected the battery do i need to anything else when starting it

[@CJ-gq6ol]

Hello just come across your video and wanted to ask if disconnecting the battery and re connecting would result in the same fix. I've just got a focus mk4 I've tried everything to get start stop working disconnected all or any usbs potentially using the battery turn the fans off and all sorts no luck. I'm wondering if mine is the exact same issue and if there is any concerns with disconnecting and reconnecting a ford battery. Will everything boot back up properly?

[@SYDiagnostics]

If the battery is fully charged and the sensor is mis reading, then disconnecting the negative terminal for 5 mins or more should work

[@CJ-gq6ol]

@SY Diagnostics thank you for the quick reply really appreciate it will give this a try. After my commute today I again tried everything and nothing was working. Is stop start really a good thing to be using anyway in the long run won't it actually be worse for the engine?

[@SYDiagnostics]

@@CJ-gq6ol the components are "beef'd" up to allow for stop/start so there are no issues. The system is emissions related, so for the polar bears and Greta its best for it to work

[@CJ-gq6ol]

@SY Diagnostics haha okay ill keep it on. Just wanted to say I tried the negative disconnect left it out about 20 mins and disconnected the sensor. This didn't work for me in optimal circumstances outside temp engine temp fans of everything no luck still. What DID work on focus mk4 the bsm reset is flash full beam 5 times brake pedal 3 times the battery flashed and it reset. The car is now fully working with start stop every time. HOWEVER the sync 3 system this morning had a message saying something along the lines of it won't start up until the engine is started due to low battery. I don't know if that was because the bsm reset or a genuinely low battery car is 2019 so battery may be from new and nearly 4 years old. I want to get an obd reader just so I can do general checks car is under warranty but I like to know myself. Is there any you would recommend no more than £80 or so? I watched your other video on the forscan but my laptop is well and truly passed it lol

[@SYDiagnostics]

Forscan would be the tool I'd recommend. The bms reset you have carried out seems to have worked (probably not now) but with the message showing on sync I'd check the battery state of charge as shown in the bcm. For now I'd disconnect the battery monitor, fully charge the battery and refit the sensor....then try

[@pedroaires1199]

Im not specialist, but I read a lot about Ford Mk4 because I have one. I think it's more important to reset BMS than BCM. BCM needs eight hours to relearn the battery state of charge, and this can be done every night. The BMS we need to reset it once every 5 years or when we change the battery. I solved many Start/Stop problems in this model using the BMS manual reset (without Forscan): kzbin.info/www/bejne/aXLWp3t8mdmsZ6M

[@SYDiagnostics]

Resetting BMS still requires 3-6hrs of

[@mohcineawzen5284]

Bnjr

[@seankirby2580]

Watching your very good videos reveals you cannot differentiate "were", the plural of "was", from "where", the location. Please get a grip as it's irritating.

[@SYDiagnostics]

in relation to which part of the video?

[@seankirby2580]

@@SYDiagnostics Each one of your videos that uses text captions, you always write "where" instead of "were".

[@SYDiagnostics]

@@seankirby2580 thanks for the heads up..... Easy mistake I'm just a mechanic who left school many years ago lol

[@seankirby2580]

@@SYDiagnostics You're welcome. Your videos are superb, so no need for the irritation. Many thanks.

[@marion1600]

@@seankirby2580 🙄