JKJ

This week I started getting an intermittent "Adaptive Light Defective" message on my 2015 3.0T Prestige with ~39k miles. It doesn't come on unless you turn on power and don't start the engine for at least 10 seconds. If you unlock the car and start the engine directly, the error does not post. Regardless of whether the message posts, the adaptive lights are clearly not working. The power-on self test where they pivot down and up before finding level doesn't happen, and they're not swiveling during cornering or stepping up to highway mode when travelling fast enough. Something's broken, but what? I thought the message was supposed to come on and stay on if the module was bad or a wire was broken, so this has me a little confused. It's cold out, so I don't really want to do exploratory disassembly without some idea of what i'm looking for. And of course, I'm hoping I don't need a new headlight - those are expensive!

Edd W

It could easily be a level sensor failing. The adaptive lights need the suspension to be working normally or they stop working and just sit at a default position.

Check codes - as always with these type of faults.

JKJ

I had the car in for brake work today and had them take a look at the lights error message. Turns out the Headlight Range Control Module had failed. Fortunately I'm still in warranty for a few more months, otherwise it was a $450 part. Still cheaper than a new headlight, though!