Hello friends. Bought my daughter a 2006 Mini Cooper S Convertible that she was dreaming about and it has a gremlin...new one for me... On Saturday, I was test driving it after replacing the power steering pump. turned it off and it went dark. Didn't respond to key fob buttons or putting the key in ignition. Absolutely nothing - no lights, no clicks, no beeps. Key turns as expected, just no response at all. Might as well have been a car without a battery. Checked the battery voltage at the underhood terminals and it was sitting at 12.6V. An hour later, tried again and lights came on, and started right up. No codes from that event.

I've been driving it every day now to see if I could capture the problem - today it happened again at my work. SES light came on while driving. Parked and turned the engine off while I got the code reader out - everything went dark again - no lights, no clicks, code reader wouldn't connect, doesn't respond to key in ignition or the buttons on the fob. So far its been about 4 hours and it hasn't come back. Battery voltage still ok.

First thought was the ignition switch, but I don't see why that would keep the keyfob from locking or unlocking the doors and/or trunk (I wisely left the seats down to be able to reach the battery if needed). Maybe fusible link next to the battery? If that was open, wouldn't the terminal under the hood read 0 volts?

Edit: I tried both keys I have for the car and same response with both.

 

I would first try the ground cable under the hood. My '04 connects to the motor mount. Disconnect your battery, clean and reattach the ground cable connected to the motor mount, reattach battery. See if that makes a difference.

 

battery voltage 12.6 volts still. At the battery and at the under hood jump point.

Went to check the grounds, which I had cleaned up recently and noticed the power connection into the under hood fuse and relay box was just finger tight. I must have left it like that after cleaning all the grounds.

There was an unsurprising sizzle as I snugged it up after which the car woke up and cranked on the first try.