Anyone else getting dcdc charge fault & more errors leading to MG5 breakdown?

[MickeySw]

Cheers, yeah I fitted a new 12v battery got the car driving and took it to a Rapid charge! It accepted the charge but when driving the battery only showing 11.8 and when I got home its not accepting an AC charge! I’ll get it booked into the EV garage tomorrow but it’s obviously a part needed that allows an AC charge and that works like an alternator on an ICE vehicle?!?!

The CCU (Combined Charge Unit) in a MG5 has two functions:

• provide low voltage power (14V ish) when driving or charging
• convert AC mains voltage into DC battery voltage during Type1/2 charging

You’re correct, it certainly looks like the CCU is defective (or fuse ‘M’ under the hood has blown)

It’s essential to externally charge the 12V aux before you attempt to drive it again as it currently provides all low voltage power which it’s not designed to do.

 

[Richierich37]

The CCU (Combined Charge Unit) in a MG5 has two functions:

• provide low voltage power (14V ish) when driving or charging
• convert AC mains voltage into DC battery voltage during Type1/2 charging

You’re correct, it certainly looks like the CCU is defective (or fuse ‘M’ under the hood has blown)

It’s essential to externally charge the 12V aux before you attempt to drive it again as it currently provides all low voltage power which it’s not designed to do.

Cheers man,

I’ve just fitted a brand new 12V battery and have about 76% range left so hopefully that’ll be enough to get me to the EV garage to let the professionals deal with it!

 

[MickeySw]

I’ve just fitted a brand new 12v battery and have about 76% range left so hopefully that’ll be enough to get me to the EV garage to let the professionals deal with it!

It’s highly recommended to externally charge even a brand new 12V aux overnight as you don’t know how long it’s been sitting on a shelf.

The car will shut down immediately once the 12V aux goes below a certain limit (11.8V is too close for comfort imho), regardless of the SoC of the main battery.

 

[Coulomb]

Yes, charge the 12V battery with an ordinary 12V battery charger! The car could shut down any moment with only 11.8V.

 

[Richierich37]

It’s highly recommended to externally charge even a brand new 12V aux overnight as you don’t know how long it’s been sitting on a shelf.

The car will shut down immediately once the 12V aux goes below a certain limit (11.8V is too close for comfort imho), regardless of the SoC of the main battery.

Ok thanks, any idea how long it can drive for if not using any 12V stuff in car? The EV garage is about 30 mins away on the motorway

 

[kevin ellard]

Ok thanks, any idea how long it can drive for if not using any 12v stuff in car? The EV garage is about 30 mins away on the motorway

Tricky question to answer. Try to turn off everything electrical. I think the lights will still be on but the battery can cope with those. Does anyone know if there is a way to shut the infotainment system down as much as possible? If you've got an alternate route , I'd consider it. Recovery will be more complicated on the motorway.

 

[Richierich37]

Tricky question to answer. Try to turn off everything electrical. I think the lights will still be on but the battery can cope with those. Does anyone know if there is a way to shut the infotainment system down as much as possible? If you've got an alternate route , I'd consider it. Recovery will be more complicated on the motorway.

Didn’t want to risk it so I’ve arranged a Recovery Company to lift the car tomorrow morning and deliver it to the EV garage! Just not worth the hassle of breaking down on way there! I’ll keep you posted with the EV garage diagnostics!

 

[Richierich37]

Tricky question to answer. Try to turn off everything electrical. I think the lights will still be on but the battery can cope with those. Does anyone know if there is a way to shut the infotainment system down as much as possible? If you've got an alternate route , I'd consider it. Recovery will be more complicated on the motorway.

Well the EV garage are 99% it’s the onboard charger that’s gone and unfortunately they can’t fix it as it’s a MG dealer part only that needs coded to the car! They are running more checks and will confirm tomorrow! The part is over £2k alone ***

 

[Richierich37]

Yes, charge the 12V battery with an ordinary 12V battery charger! The car could shut down any moment with only 11.8V.

I got the car lifted and recovered! MG took the car in, £320 to diagnose the fault and confirmed it’s the CCU (onboard charger) that needs replace so my total bill is £2773 and they’ll be working on it next week once the part arrives! Car is nearing 3 years old but has covered 98k miles as I’m a Private Hire. Hopefully it can do another 98k and nothing else at that price blows! Cheers guys

 

[Richierich37]

Kind of, neither the dealer or MGUK could fix it. In the end I had to take legal action and the dealer replaced the vehicle.

Got the call from MG today and unfortunately the car won’t drive now, I’ve had to pay another £1800 for a battery module that works in tandem with a CCU I’ve just paid them £2773 for! What an absolute joke as when the car got taken in it was driving and only showing a charging fault!!!

 

[MickeySw]

Got the call from MG today and unfortunately the car won’t drive now, I’ve had to pay another £1800 for a battery module that works in tandem with a CCU I’ve just paid them £2773 for!

Not sure what ‘battery module’ they are talking about. Certainly not mentioned in the service manual in connection with CCU replacement, unless it’s the VCU that’s always replaced as a last resort?

 

[Everest]

Well the EV garage are 99% it’s the onboard charger that’s gone and unfortunately they can’t fix it as it’s a MG dealer part only that needs coded to the car

Am I missing something? I thought the 'right-to-repair' laws meant that manufacturers had to make available such info for independent garages?

 

[Richierich37]

Am I missing something? I thought the 'right-to-repair' laws meant that manufacturers had to make available such info for independent garages?

The CCU needs coding in and only MG can do this, my independent garage could have replaced the part but doesn’t have the tooling or software to code in?!

 

[MickeySw]

The CCU needs coding in and only MG can do this, my independent garage could have replaced the part but doesn’t have the tooling or software to code in?!

It is possible for an independent garage to purchase a VCI and download the necessary service software from the MG service portal.

Folks do it DIY style for the MG4, should be similar on the MG5

Thread 'Diagnostic VDI, VNCI, MDI with MG4'

Jul 14, 2024

[ Edit moderator: Links to various useful posts for quick access. Mention @Coulomb to have more links added.

A tutorial guide for software updates.

Trophy/Luxury 22/23 FICM loading guide (separate thread).

The various SAIC server access plans and costs.

An inexpensive VDI dongle needed for any update work. See a few posts later for alternatives.

An alternative TBOX updating method using a USB stick and SIPS.

]

Hi all my other cars I have/the wife has owned I've had the diagnostic interface & dealer software

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Tech2 & TIS2000 for Saab
MDI &...

• haloweenhamster
• diagnostic interface mg4 software
• Replies: 484
• Forum: MG4 EV Forum

• 

 

[kevin ellard]

Folks do it DIY style for the MG4, should be similar on the MG5

They are very different vehicles. You could argue that they aren't even the same make.

 

[MickeySw]

They are very different vehicles. You could argue that they aren't even the same make.

That may well be, however OEM diagnostic/service tools usually work across the complete model range…

 

[Muffler]

That may well be, however OEM diagnostic/service tools usually work across the complete model range…

Agree. I have 4 + 5 and successfully access both via VNCI dongle and SIPS software without issue.

 

[Richierich37]

Not sure what ‘battery module’ they are talking about. Certainly not mentioned in the service manual in connection with CCU replacement, unless it’s the VCU that’s always replaced as a last resort?

Well I got the car back yesterday, total bill £4466 I had a meeting with the manager and master tech that did the work where they explained the repairs and gave me the parts away Did 160 miles today and all is well, it’s on charge now and no issues I’ve added the invoice showing the repairs (if you’re interested) and the parts damaged/replaced! Just glad it’s over now, it’s been a stressful 4-5 weeks

 

[Coulomb]

Not sure what ‘battery module’ they are talking about.

With the explanation on the final bill, it seems that it's the high voltage distribution module, which seems to be a glorified junction box plus it seems (at a stretch) the pre-charge resistor, and possibly the main contactors. But the pre-charge resistor and contactors are usually in the main battery module.

It's a sign of the times that the cracked and scorched ceramic resistor (worth perhaps £25) was replaced by swapping out the whole distribution module (costing £1700 presumably plus tax), and would have been a fair bit of labour to replace (all those stiff orange cables with their bolts). If only more repairers did board level repair. Actually, the pre-charge resistor is sometimes bolted in with flying leads, meaning no soldering required, just a smaller socket for the wench!

 

[Everest]

It's a sign of the times that the cracked and scorched ceramic resistor (worth perhaps £25) was replaced by swapping out the whole distribution module (costing £1700 presumably plus tax), and would have been a fair bit of labour to replace (all those stiff orange cables with their bolts). If only more repairers did board level repair.

almost unbelievable.

They even invoiced it as a Honda, doh.

Oh well, at least the OP now qualifies for a "FREE top up to your screen Wash".