Interesting. Any time I have issues like this I usually suspect a bad connection somewhere.

Here's where I'd look in order:
1. Fuse box under hood. If any fuses are not the newer style brass metal type, replace them. Also inspect for any corrosion. Also, take a fine sandpaper and clean the contacts where the fuses connect in the box.

2. The grounds for the light. and make sure they're referenced to the chassis ground near battery ground.

3. The switch above the CCU push buttons.

Many electrical problems in these cars come from problem number one.

__________________
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