MG3 wont start & dead instrument cluster, what causes it?

[@EmmaJ2302]

WOW! I'd like to say a HUGE thankyou for such an informative and easy to understand video. My mechanic had gotten to the end of his abilities in finding the problem with my car (exactly the same issues you describe - everything working fine except starting it up, no dashboard lights at all, no radio and no full beams - on turning the key I just got a very quiet click with no crank). This morning, my car was due to be towed to the nearest dealership 20 miles away - after lots of internet browsing and coming up blank since last week, I found your video and forwarded to my mechanic. This is the exact issue and has saved me a fortune by not having to cover the dealership repair costs at a time where I am financially struggling. You are an absolute superstar! Thankyou SO much!

[@pistonbroke]

Not a problem, thanks for watching. Check out the other video where I moved the dc/dc converter to prevent it happening again.

[@genethomas2000]

Legend. This exact thing happened to my Sons MG3. Thanks to you and a £79 replacement part off ebay we got it working again.

[@BlazeFalconburger]

Amazingly helpful! Just had this exact problem and this solution has solved it! The wife's Stop start wasn't working anyway since we bought it, so just bypassed it and not bothered about replacing the unit.

[@pistonbroke]

Stop/start will still work with this unit bypassed. what may happen with the dc/dc bypassed is during a restart the instrument cluster will go through the self test and the radio will go off and back on. Low battery voltage is the main cause for stop/start to not work.

[@denveranderson3829]

DAMMMM YOU LEARN SOMETHING EVERYDAY HEY! I BETTER CHECK MINE TOMMORPOW AS MY CAR PARKS OUTSIDE IN THE BACK YARD. MORNING BECAUSE WE HAVE RAINY WEATHER AS I'M TYPING HERE IN SOUTH AFRICA! THANKS FOR THE HEADS UP PBG!!

[@pistonbroke]

No need to shout.

[@grahamjohnson2685]

Thanks for posting this. It was a great help. My daughters 2016 MG3 had exactly the same issue. After watching the video I went straight to the rear passenger side of the car and found it swimming in water. 👍

[@pistonbroke]

Glad to help. Don't forget to find and fix the water leak. See my other video where I moved the dc/dc convertor to a higher location.

[@WT5R]

Bridged the connector got dash lights etc but still no crank. No power to starter signal wire. Any ideas? Thanks

[@trevuk01]

Thanks for posting this its saved me a load of time. I had found the 30 amp fuse but didn't know what or where the dc-dc converter was. My first thoughts would have been a drop-down voltage for the dashboard but you saved the day. Thanks.

[@pistonbroke]

No problem, check out my latest video where I move the dc/dc converter to prevent water damage.

[@NigelPettit-e6f]

Hi there...thanks for this video...I have exactly this problem and have replaced the fuse but it is sopping wet under the carpet. Am I right in thinking the DC DC converter is under the front passenger footwell? What does the unit do other than the start/stop function? I would like to know what I would lose if I bypass it as suggested until I can get a new unit.

[@pistonbroke]

It's under the passengers seat. Stop/start will still work if it is bypassed. What it does is during a stop/start restart it prevents the instrument cluster from doing a self test like it does when you first start it and it stops the radio and heater from going off and back on. All this would only happen if the battery voltage drops low enough during a restart.

[@NigelPettit-e6f]

@@pistonbroke Do I assume you mean under the FRONT passenger seat? In other comments you state that it can be left bypassed long term...does this mean I just lose the start stop function but everything else works as usual? Sorry but would need to clarify....thanks again and best regards Nigel

[@pistonbroke]

If you actually watched the video you'll see exactly where it is and if you read my last reply you'll see that I said the stop/start will still work when it's bypassed and I even went to the trouble of explaining what it does.

[@cherylmuratore]

Thanks for this, a real eye opener and well delivered, cheers.

[@caddo8760]

What numbers on the dc converter do you connect wire to bypass?

[@pistonbroke]

2 & 4

[@chadramsden6477]

Fantastic what a life saver 👌sorted mine straight away exactly as you said, cut and soldered the two wires bit of heatshrink tube as my wife doesn't like the stop start anyway... perfect👍thank you so much

[@pistonbroke]

The stop/start will still work without the dc/dc convertor but the radio and instruments may go off and back on during restarts if the battery voltage is low enough.

[@BetfairTradingCommunity]

Hi Chad, has this worked? I’ve got same problem and there are none of these converters anywhere to buy!

[@stuartmatthews1966]

Thank for a great video. Has just happened to me. AA guy had it nailed but the MG garage I got it recovered to can't work on it for 3 weeks and still want to run a full diagnostic test! Where can I source the DC DC converter unit from and can I replace that and the fuse myself? Many thanks

[@pistonbroke]

Easy enough to do yourself. Fuse you can get from any auto factors. Dc/dc is only available from MG but you can get used ones off ebay. Just make sure if you get a used one that it's not been flooded. Fit the new dc/dc to the seat cross member to avoid this happening again. I've done a vid on how to do this.

[@caddo8760]

Do you have a list of tools/equipment to carry out this work please?

[@frankhavard277]

My 2015 has similar non- starting problem and dash shows Err2 - is this a similar solution? Starter cranks with direct feed, but with out this nothing

[@pistonbroke]

No, 2015 doesn't have a dc/dc converter. Yours has an immobiliser problem. With the dash showing err2 suggests an issue with the BCM.

[@BetfairTradingCommunity]

Thanks for a great video. MG have told me that my car does not even have this part so cannot help. Even though it clearly does! Is it safe to bypass this unit? Or does it really need replacing? If I bypass it will it not just cut out again eventually?

[@pistonbroke]

Yes you can bypass it.

[@stewartpearce1279]

You do know your stuff about the mg 3 as you are right with the problem on the bonnet latch it is reading that there is no power going to it. Can it be replaced at home with a new one or will it need to go to mg thanks

[@pistonbroke]

It's easy to replace. Front bumper needs to be removed first, or at least pulled forward enough to give you room. 3 bolts hold the latch on.

[@Ace-ee3wn]

Great video, have all the symptoms, sounds like a puddle when I press the carpet under the seat however don’t cannot get bonnet lever off to remove trim or carpet plugs under rear seats. Does anyone who has done this have any advice for removal. Thank you

[@pistonbroke]

The lever just prises off, watch you don't lose the little metal clip inside the lever as it comes off.

[@TeslimAkintilo]

Thanks so much for this information... I just went through the process now and my MG3 2017 has started working. Can I continue using it that way after bypass?

[@pistonbroke]

Yeah you can leave it bypassed but make sure you use the same thickness wire as what is on the plug and that the connections are good, a fair bit of current goes through it and the last thing you want is a fire!

[@stewartpearce1279]

Thanks for that useful info I think i have to lift my wife unit off the floor base at the weekend . My wife's mg3 has a annoying fault it pings all the time saying there's a door open it looks like it's the bcm can I buy a second hand one and install (reprogram it) or is it a new one only and does that mean deals only

[@pistonbroke]

That'll be the bonnet switch. Common fault, It comes as the whole latch. It's never the bcm and you can't fit a used one anyway as they can only be programmed once. When testing, it always points to a bcm fault. There is a resistor in the bonnet switch so joining the wires together doesn't work and gives the impression it's a wiring fault or bcm.

[@stewartpearce1279]

@@pistonbroke wow thanks for getting back to me so quickly so what can be done about is it just change the bonnet catch and will that need any programming

[@simout3877]

Great information sorted my car today cheers

[@gabriellaperez7244]

What is it called the wire you used to bypass it and we’re could I get one from we have this problem right now

[@pistonbroke]

It's just a piece of wire with some terminals crimped on each end. You can't buy it, you'll have to make it.

[@gabriellaperez7244]

@@pistonbroke okay thank you

[@watchalot919]

Is the door seal issue sorted on the facelift version?

[@pistonbroke]

We don't see as many facelifts with water leaks through the door seals so maybe they have sorted it. The dc/dc convertor no longer lives under the passengers seat on the facelift so even if it did leak, the car wont die.

[@Wroe]

Fantastic stuff the same fault has happened to MY 2016 MG3 and I am going through the process of fitting a new one. Are these modules plug-and-play? no coding is required for the vehicle.

[@pistonbroke]

Yeah, plug and play.

[@Wroe]

thanks for the reply, Do you do any other electrical problems with these cars .. I have a couple, unfortunately. a new engine has been fitted but the people who fitted it have wired up the vehicle incorrectly. where would I find the connection looms or where could I get hold of wiring diagrams for the MG3 please .. @@pistonbroke​

[@pistonbroke]

What have they wired incorrectly? It's pretty difficult to get it wrong as all the connectors will only go in the place they are supposed to.

[@Wroe]

the car now thinks that it is always open so when you press the key fob it beeps to inform you and when you pull away it beeps when you set off this could be a separate problem .... though .. stop-start doesn't work anymore. and when you turn the rear wiper the front comes on instead lol @@pistonbroke

[@pistonbroke]

Door open warning is caused by a faulty bonnet latch or they haven't plugged it in. Stop/start is usually caused by low battery voltage. Is the yellow eco light on? Or does the green eco light flash 3 times when you stop, select neutral and take your foot off the clutch? Rear wiper I wouldn't know off the top of my head, that will need investigating although I highly doubt it has anything to do with the engine change.

[@andrewheale4738]

After being away for a week , car won't unlock on the fob had to insert the key to open the door. Discovered battery as dead as a Dodo, had the AA out under the service plan and fired the car up, AA man said that im not using it much to give the battery a good charging. Spoke to the service manager here in Swansea and he said when going away double click the fob key to switch other items off as they are still using battery. Is hey bullshitting Me Steve? 71 plate MG3.

[@pistonbroke]

To put it bluntly, yes he's full of shit. I've seen this problem a few times before and whenever I've done some testing I've found nothing wrong. What I have found though is that if the car is left unlocked, it will kill the battery over about 5 days. Yours was locked so it's not that. It's a weird fault and may never happen again. The only thing I can think of is the BCM randomly wakes up and drains the battery. It more than likely does this by interference from other radio transmissions around the same frequency as the remote. Lack of use will bring the battery down to an undesirable level but it shouldn't kill it completely unless there's something wrong with the battery.

[@christianpullen2165]

If under warranty it would go back to where where mg put it or do your mod?. Plus what do you suggest future proofing it eg when the seals start to getting hard or notching it's damp change the seal?

[@pistonbroke]

When in warranty I put it back where it's suposed to be but space it up away from the floor, out of warranty, I do my mod if the customer wants it.. mg say to drill holes in the floor and put tube grommets in to let any water out that may get in.

[@BlueStu-jf9zm]

Hi, great help. Thanks a lot. Just to clarify though, is it the pink/white wire linked to the black wire. Also, how heavy does the cable need to be? Thanks again.

[@pistonbroke]

Pins 2 and 4. Brown/blue to brown/pink. The wire needs to be the same gauge as what is in the plug. That's why I made the bypass thingy. I used the pins from the old dc/dc plug which are the correct thickness.

[@BlueStu-jf9zm]

@@pistonbroke brilliant. Thanks again for the help. 👍

[@deevc133]

Hi, Exactly as you have described, bought a dcdc converter from eBay and the car is running. What I can’t find is any new door seals. MG directed me to to Browns and Gammon but they just told me they don’t have any. Any ideas where I can get the door seals from?

[@pistonbroke]

The only place really is a main dealer.

[@drmarkgillespie1787]

Really helpful, despite no water showing under the carpets in my car was sodden and the converter went- £160 later I have a new one. Is it the front, back or both seals that tend to go?

[@pistonbroke]

Could be any of the seals. You need to water test it. See my other video where I moved the dc/dc to a better location where it wont get wet.

[@Stairheedrammy]

Which colour wires did you link to get the car to start again- great video, thanks

[@pistonbroke]

purple/white & purple

[@dereksquires6369]

Just had the same problem with our Oct 2018 MG3. Main dealer has had it for ten days and only just found the problem! They haven't even looked for the source of the water leak yet!

[@pistonbroke]

10 days!!!!!! I've seen this so many times, it's a common fault. MG know about it and by now I would have thought all dealers would know too. I work at a MG dealer and have known about this for well over a year. Some dealers make us all look bad, a hose pipe will tell them where it's coming in. 99% of the time it's one of the door seals, usually the passengers rear.

[@dereksquires6369]

@@pistonbroke Thanks for that. The car was started by the AA under MG Warranty, by bypassing a couple of the fuses. I told the dealership exactly that, and it took them nearly a week to come back to me to say there was no fault on the car (as everything was working), but "someone had put some strange wires in the fusebox". I suggested it might be a good idea to remove those 'strange wires' and see what happened, and surprise, surprise, the next day they phoned to say that the car was dead! Couldn't make it up, could you!! They were then waiting for a wiring diagram from MG Motor UK so that they could troubleshoot!

[@dereksquires6369]

The car is kept in the UK with family for our occasional use when we're back from Spain. Original fault was noticed as the headlights apparently came on when the car was parked, and the following morning the car was dead. Could that have been a result of the DC/DC converter shorting internally? I didn't get to see any of this!

[@pistonbroke]

@@dereksquires6369 What bullshit, they are fobbing you off. Wiring diagrams are on the diagnostic laptop, they already have them and if for some strange reason they dont then they contact MG via service now and MG will send them a link to download it. Jeez I've heard it all now!

[@pistonbroke]

@@dereksquires6369 Yes more than likely although I've never seen that myself, they usualy get recovered in dead.

[@79RockShox]

Many thnks for posting this video mate, saved me hunting the issue out on my mums one, sat in an inch of water, have you any idea what MG are charging for a replacement one? I've literally only just done the clutch and fork repair/replacement due to that stupid plastic bush being open to the elements, honestly, this car it's like they got it 95% decent and decided not to giv e a shit about the last 5%, it's a shame as they drive OK and feel solid on the road!

[@pistonbroke]

I think they're about £160. See my latest video about bypassing it. kzbin.info/www/bejne/eYq5qKGwea2eg6M

[@yonellowernet5984]

I have similar issue...but ours is a 2012...it has dash but no ignition & spark. It had water in the car (which resulted clogged sunroof drain. But signals are not getting to the fuel pump and ignition coils...every fuse and relays are good. Don't know what the problem might be.

[@pistonbroke]

I can't diagnose an electrical fault without seeing the car. Sorry

[@79RockShox]

Thanks again mate, out of interest did you change the door seal or treat it to a silica based spray? Edit: To be fair I think I'll make sure she trades it in, at 66 she needs a reliable jap car in my eyes but she hates the look of them... function over form mum! lol.

[@ash7990]

Do pre stop start cars before 2016 have this unit?

[@pistonbroke]

No

[@ash7990]

@@pistonbroke sorry just watched the last part of your video and realised you answer my question on the video. That's good to know

[@scotttt93]

I have this exact issue with my MG3 but it’s a 2015 (65 plate) and there was water exactly where you said too. Would this not be the issue given you said only 2016 onwards have that unit? I took it to MG and they couldn’t diagnose the fault for weeks, in the end they said it needed a new wiring loom which made it start intermittently. Now it doesn’t work at all again £850 later!! Any advice would be appreciated

[@pistonbroke]

Yours being a 2015 will not have the dcdc convertor so water in the footwell would not be the cause. How can they say its a wiring loom? Looms can be fixed without having to replace it. Besides, £850 seems awfully cheap if they did replace the loom. The loom on its own is about that plus about 30 hours to replace it as the whole car needs to come apart. I very much doubt they replaced it. Right then, first check this. Take off the under bonnet fusebox cover, in there is a white plug, pull it out and check for water ingress and corrosion in the plug and fusebox.

[@scotttt93]

@@pistonbroke Thanks for your response! Yeah it all seemed dodgy to me with MG, its worth noting that the car was completely dead like in your video, however we charged the battery after a jump start didnt work and now it turns over but just doesnt start (we think the lights were on low which drained the battery even though the dial was set to off - weird). We've also had it try and start itself a few times with the key being in but not even being turned. I will check the plug and fusebox tomorrow. If this is the case and its corroded whats the next step? Or if its not that then what to try instead? Appreciate your help on this, where in the UK are you based out of interest?

[@pistonbroke]

@@scotttt93 I'm in South Wales. I've had issues with headlamps before on the 3 and it turned out to be the switch. i'll try and help with this but it's not going to be easy without having the car in front of me. Are you on facebook? if so, join my group and you can post videos of the faults and I can try to guide you in the right direction. facebook.com/groups/340443653866985/ Do you have electrical test equipment? multimeter etc?

[@scotttt93]

I’ve joined the group and can post videos but all it will show is me trying to start it with it cranking but not starting - unless you need me to video something specific? The white plug/fuse box was not corroded or water damaged, however when I took it out to look and put it back in again it randomly started when I cranked it? I gave it a 30 minute drive and it was a little shaky but ran okay without stopping. However today it now won’t start again, I tried taking the white plug out and putting it back in again in case it was that but no luck. I have a multimeter yes - any ideas? Cheers

[@pistonbroke]

So it does crank but not start? First off you said you had the exact same issue as the dcdc fault. Does the instrument cluster work? Post a video of it cranking so I can hear the engine. You may have a timing chain problem, common on pre 2016 mg3's

[@shogunkarate7407]

Great Video! My wifes is 4 years old so not covered by the warinty! Going to cost £400 to fix by the Dealers! But wont this keep happing when it rains? Would love your opinion?

[@pistonbroke]

You need to find and fix the water leak otherwise it will happen again.

[@sarahcripps3393]

Hi what socket size did you use to take out the seat please? Also could I just buy a new converter and fit it myself or would it need to be done by a garage due to resetting etc? Thank you

[@pistonbroke]

T45 for the seats. Ecu is plug & play so no programming needed.

[@sarahcripps3393]

@@pistonbroke great thank you very much. Dealer is going to charge me £600+ for repair but with your video I feel confident to do it, thank you so much 😁

[@sarahcripps3393]

Are there any other tools I may need, etc different socket size for seat belt? Thank you

[@pistonbroke]

@@sarahcripps3393 17mm socket or spanner for the seat belt, trim remover tool to prise the bonnet release lever off and to prise off the sill trims.

[@sarahcripps3393]

@@pistonbroke great thank you very much you are a life saver! 😁

[@ourkarl6239]

Hi , great video . Did you find the area where water was getting in ? Were having the same problem .

[@pistonbroke]

It usually leaks from the door seals but you'll need to water test it

[@yonellowernet5984]

If you have sunroof...the drain could be clogged

[@pistonbroke]

Mg3 doesn't have a sunroof. Not in the UK anyway

[@yonellowernet5984]

Ok...didn't know that. Wel..that was my problem...the sunroof drain clugged

[@ashrafabdulla7404]

Nice information 👌thanks 👍

[@s.mulcahy8211]

Where can I buy a convertor, looking on-line, but not sure if they are available

[@pistonbroke]

Mg dealer. They're not that expensive

[@s.mulcahy8211]

Thanks mate, I'll contact one tomorrow, hopefully they will post/ship one to me. Great video 👍🏻

[@faz752]

Nice one brother 🤜🤛

[@briantingle2069]

well done sir and thank you+++++++++++++++++++++++++++++++++++++++++++++++++++++

[@pistonbroke]

No problem