This is quoted from a member on jeepgarage-
“I have successfully changed the values with Appcar DiagFCA. Those are the same default values. It took some understanding of how it works and two attempts. I will try to log back in and tell you the values but the changes I made are not that dramatic. I had the same issues with full sunny weather in the morning, but facing away from the sun, and the headlights would be on.
I increased the ON threshold to 3.75 V and also the OFF threshold to 2.75 V but I will double-check. The logic is that the darker it gets, the higher the Voltage reported by the sensor. So you set the threshold for activation at a higher Voltage read-out by the sensor (i.e. it is darker outside) and the threshold for turning off also higher, so the headlights turn off sooner. You have to change both, otherwise and possibly even make the difference between them smaller than factory settings. If you just change the ON value, requiring a higher voltage for activation = darker outside and leave the OFF value unchanged, then as it gets progressively sunnier / less overcast etc. your headlights still stay activated because the sensor will trip the circuit when daylight hits cloudless Hawaii beach levels.
Auto Headlamp ON Threshold: 3.75 V
Auto Headlamp OFF Threshold: 2.75 V”
I tried setting tunnel detection before, and it just caused the headlights to stay on all the time with no way of shutting them off (until the truck was off).