Speedometer illumination -- not the bulb or fuse

[timinla]

I have a 2008 M45s. I have had very few problems with the car over the last ten years and 170k miles. But I have one now. When I turn on the car and during daylight hours, the speedometer illumination works just fine. As soon as the headlights come on however, the lights on the dash go out. This occurs whether I turn the headlights on manually or allow the automatic feature to turn them on. I can't believe it's a bulb or fuse issue as the illumination is just fine until the headlights come on. Any thoughts?

[EdBwoy]

I think your dimmer switch/dial is bad and will need to be replaced.

I assume at 10 years you haven't messed with it's settings that much. Try setting it to max brightness and move the headlight stalk around.
Do the cluster lights go off or stay on when the switch is set to parking lights?

[CarGuy87]

What's happening on my 2008 M35S.

1. As soon as I turn on the headlights the cluster dies (except for the small warning lights: headlights, foglights, etc)

2. The entire dash has no lights (except the yellow/green LEDs near the climate/audio area) but the clock or all the buttons with numbers, nothing has lights.

Fuses under near driver's side all seem ok.

[Costee]

What's happening on my 2008 M35S.

1. As soon as I turn on the headlights the cluster dies (except for the small warning lights: headlights, foglights, etc)

2. The entire dash has no lights (except the yellow/green LEDs near the climate/audio area) but the clock or all the buttons with numbers, nothing has lights.

Fuses under near driver's side all seem ok.

The lighting/turn signal switch could be malfunctioning.

[CarGuy87]

Ok for documentation purposes I decided to reply to this. Issue is fixed.

When I bought my M35S it had a dealership warranty so I brought it in and an auto electrician fixed it. It was a short SOMEWHERE. Outside of my scope of auto repair.

[Ilya]

Ok for documentation purposes I decided to reply to this. Issue is fixed.

When I bought my M35S it had a dealership warranty so I brought it in and an auto electrician fixed it. It was a short SOMEWHERE. Outside of my scope of auto repair.

Thank you for looping back and providing the resolution. It will at least give our readers a path to go down.