Xenon headlight switches itself off

[con1981]

I'm currently trying to work out all the bugs in my 172.

When my headlights are on automatic both headlights come on and then after awhile the passenger one switches off.

When the lights are put in manual mode they stay on for the whole of the journey.

Ideas please how to sort this.

 

[Ryzigger86]

Check for water in the ballast unit on the bottom of the headlight,swap the ballast packs over and see if I goes to the other light