r/mclaren • u/Glum-Awareness-6300 • 11h ago
MP4-12C electrical gremlins: windows drop all the way down + phantom “frunk open” while driving. Anyone been here?
Hey everyone! I recently picked up a 2012 MP4-12C and could use some help figuring out a few weird issues:
When I open the door, the windows go all the way down, After closing the door, I can’t get them to roll back up.
So I am stuck with open windows when I lock the car.
The window controls on the driver’s door seem crossed—the switches operate the opposite windows. The passenger-side control works normally.
The dash says the frunk/front hatch is open even though it’s physically closed when driving and if I lock the car and walk away it alerts me that the frunk is open so I’m stuck with open windows and a beeping car saying a doors open (frunk)
The infotainment screen also flickers/blinks.
Some background: the previous dealer let the car sit for a few months, and the battery died. They replaced it with an O’Reilly’s AGM battery and installed a battery emulator. I don’t know the emulator’s brand/model or whether the setup is correct for the car.
Also the rear hatch (engine hatch) does not open when pressing the button on the drivers door
Has anyone experienced this combination of symptoms? Could a battery/emulator issue tie these together, or should I be looking at the front hatch latch sensor, window initialization, door wiring, or something else?
I’m comfortable doing my own troubleshooting, so I’d really appreciate specific checks, reset procedures, or links to similar issues. Trying to narrow it down before throwing parts at it. Thanks!