This morning I got in the car and the key-less engine start would not work. All the console light were on, but very faint. No MFD!
Then my eye caught the light switch - ON!
Damn, "Flat batteries!", I thought.
I put the key in (inspirational lateral thinking moment) and turned the key.
She started up as if nothing was wrong!
Some items were obviously re-set, such as the clock, but otherwise no problem.
The Touareg has two batteries:
- cranking (starter) battery
- "accessories" battery
It turns out that
- the two batteries are disconnected when the ignition is off
- the ECU monitors the second battery (that runs the accessories), and will switch non-essential items off when the accessory battery's voltage goes below some threshold