W205 - Dead touch pad and buttons

[AntC43]

After a 2 hours drive this morning i parked the car for 30 minutes and now there is no power to the touch pad or buttons including scroll wheels. I stupidly switched the head unit off before leaving the car (was watching something on my phone) so have no reverse camera.

Removed the Carplay MMI (aftermarket) with no change, have inspected the harness from the underside of the controller to the plug and all appears to be okay.

Any thoughts?

 

[markjay]

So the infotainment system display is working normally? Only the touch pad and scroll button are not working? Is the battery fully charged?

 

[AntC43]

I'm unable to switch the infotainment system on as the power button next to the joypad is fubar. Is there another way to switch it on?

 

[markjay]

What's the battery charge level? If you sat in the car with the ignition on, it would have drained the battery even if COMAND was switched off.

 

[AntC43]

I thought that could be the case so left it for an hour or so during the drive back from London. Point to add, the battery is new.

 

[AntC43]

Took the infotainment unit out and found two broken wires on the harness, repaired and problem solved.

 

[aminyo]

I have the same problem, it happens after trying to fit an aftermarket Screen, now the touchpad and all buttons around it are OFF. Any ideas? Checked the voltage to the touchpad and seem it’s getting 12V when ignition but nothing illuminates! (Volume, Dynamics, Auto start .. all OFF).

 

[AntC43]

I have the same problem, it happens after trying to fit an aftermarket Screen, now the touchpad and all buttons around it are OFF. Any ideas? Checked the voltage to the touchpad and seem it’s getting 12V when ignition but nothing illuminates! (Volume, Dynamics, Auto start .. all OFF).

After repairing the broken wires It's been problem free. However My neighbour has exactly the same issue on his 2018 w205, where he's also added a MMI box. Pulled the fuse (fuse box is in the passenger footwell) left it a couple of hours, put the fuse back in and it's working again. He noticed that if CarPlay is active and he switched the power off by the power button it's nearly impossible to restart the system. I believe it's more a problem with the MMI box than the headhunt.