MMI unit disables vehicle once fitted

mcbutler · Post by **mcbutler** » Tue Jun 15, 2021 4:52 pm

Hi All,
Well,
Having my replacement iDrive screen fitted today and the garage are fitting the MMI unit at the same time.
Although experienced they have not fitted one before so I sent them an email with all the youtube vids by our friend at BMW Z4 MODS.

Once installed as per the videos the car failed to start, no dash lights or anything.

MMI removed and car back to normal!!!

Anyone heard of this??

Timmyboybunter · Post by **Timmyboybunter** » Tue Jun 15, 2021 5:16 pm

Very odd - haven't heard anything similar from the handful of people (me included!) who have fitted one of these units - the car had power but would not turn over, or there was literally nothing going on?

mcbutler · Post by **mcbutler** » Tue Jun 15, 2021 5:27 pm

Timmyboybunter wrote: ↑Tue Jun 15, 2021 5:16 pm Very odd - haven't heard anything similar from the handful of people (me included!) who have fitted one of these units - the car had power but would not turn over, or there was literally nothing going on?

Absolutely nothing, dead duck! garage is attempting to diagnose but nothing so far. If it turns out that a dead MMI unit can disable your entire vehicle - even when driving I dont think I want it any longer!
Will wait and see what they come up with, at least the car iok again with it removed.
Where did you buy yours chum?

Silverstar · Post by **Silverstar** » Tue Jun 15, 2021 7:45 pm

This is very strange, if I remember correctly the only part the MMI kit that connects to the car, is in between the radio and vehicle harness, the aux port (which just plugs in) and the microphone of which there are two ways of doing it, 1) use the mic included in the kit and mount it in a suitable position and 2) tap into the car's existing mic but none of this ought to disable the car. The kit is mostly plug and play.

mcbutler · Post by **mcbutler** » Tue Jun 15, 2021 8:40 pm

Silverstar wrote: ↑Tue Jun 15, 2021 7:45 pm This is very strange, if I remember correctly the only part the MMI kit that connects to the car, is in between the radio and vehicle harness, the aux port (which just plugs in) and the microphone of which there are two ways of doing it, 1) use the mic included in the kit and mount it in a suitable position and 2) tap into the car's existing mic but none of this ought to disable the car. The kit is mostly plug and play.

Yes agreed it is supposed to be and the process is simple.
I did notice that the dip switch settings given in the youtube videos are different to the ones given by the manufacturer but hardly likely to kill the car.
I am suspecting a faulty loom/plug supplied with the unit or the unit itself.
If it is the unit/loom killing the car then the overriding question is 'what if it fails at 70mph on a motorway?'

Timmyboybunter · Post by **Timmyboybunter** » Wed Jun 16, 2021 9:15 am

mcbutler wrote: ↑Tue Jun 15, 2021 5:27 pm Where did you buy yours chum?

Mine was from AliExpress.

All very odd - as Silverstar mentions, the power to the MMI box just comes in-line from the existing head unit wiring, so even if you did have a dodgy box at the very least I'd just assume the thing would not work and you'd get some kind of warning flash up. I'm sure Dave will stumble across this thread soon and may have some insight. Possibly worth scanning to see if any codes have been generated?

AnubisZed · Post by **AnubisZed** » Wed Jun 16, 2021 9:34 am

Timmyboybunter wrote: ↑Wed Jun 16, 2021 9:15 am ...... I'm sure Dave will stumble across this thread soon and may have some insight. ...

Already on it

Timmyboybunter · Post by **Timmyboybunter** » Wed Jun 16, 2021 10:15 am

You should start charging for all this consultancy work Dave

Argyll Andy · Post by **Argyll Andy** » Wed Jun 16, 2021 10:30 am

Timmyboybunter wrote: ↑Wed Jun 16, 2021 10:15 am You should start charging for all this consultancy work Dave

I notice you’re only suggesting that after yours is in and working

Timmyboybunter · Post by **Timmyboybunter** » Wed Jun 16, 2021 10:35 am

Argyll Andy wrote: ↑Wed Jun 16, 2021 10:30 am I notice you’re only suggesting that after yours is in and working

Absolutely. My consultancy from Dave was FOC just to get the business up and running

Argyll Andy · Post by **Argyll Andy** » Wed Jun 16, 2021 11:39 am

Timmyboybunter wrote: ↑Wed Jun 16, 2021 10:35 am
Argyll Andy wrote: ↑Wed Jun 16, 2021 10:30 am I notice you’re only suggesting that after yours is in and working
Absolutely. My consultancy from Dave was FOC just to get the business up and running

Just like mine was from him too

He’s a great asset to the forum

R.E92 · Post by **R.E92** » Wed Jun 16, 2021 12:33 pm

Sounds like a problem with the CAN bus. From looking at Dave's install video it looks like the unit splices into the CAN bus.

Either the CAN controller in the MMI box is faulty or it's configured for the wrong CAN standard and is scrambling your CAN bus so none of the modules can talk to eachother. The car won't start unless the DME (engine) can talk with the CAS (module for your car keys). Check the wiring of the MMI box into the CAN and also check if any of those jumpers are responsible for selecting the CAN protocol.

Just to answer your worry about it happening when the car is running; if any comms networks fail during driving the individual modules will still work, the engine will still run but everything will be in "emergency" mode where by the run under assumed conditions, so the car will basically just limp along. It wouldn't be able to start again after you shut the engine off though.

mcbutler · Post by **mcbutler** » Wed Jun 16, 2021 4:22 pm

I received advice from Dave (font of all knowledge) Anubiszed via PM yesterday which I forwarded to my indy. They had already nailed the problem being two of the wrong plugs connected....
All up and running faultlessly now and looks great on a spanking new screen
Added bonus is my indy (RL Motor Services - earned a plug) didnt even charge me for the added labour raround the MMI at all...

Thanks for all the advice etc chaps - hope to see a lot of you in the lakes before too long

Timmyboybunter · Post by **Timmyboybunter** » Wed Jun 16, 2021 6:02 pm

Great news, hope you enjoy it - brilliant bit of kit now I've lived with it for a few months, worth every penny.

AnubisZed · Post by **AnubisZed** » Wed Jun 16, 2021 7:41 pm

Yes thats great news, glad it's sorted

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