When you are within 500 feet of an oncoming vehicle or you come up behind a vehicle.
You should dim your lights as soon as you see their lights.
when you see there lights you should dim yours
There should be a roll switch right next to your light switch on your dash to dim the lights with.
500'
Dim All the Lights was created in 1995.
You should dim your headlights within 500 feet of the car in front of you. The rule of thumb is, if you can see another car, dim your lights.
You should dim your headlights when an oncoming vehicle is about 500 feet away. This helps avoid blinding the other driver and ensures safe visibility for both vehicles. Additionally, if you are approaching a vehicle from behind, you should dim your lights when you are within 300 feet.
As soon as the oncoming car is in sight.
If you can see the oncoming vehicle then he can see you. Dim your lights at that time.
Check your alternator it could be malfunctioning. Sometimes it gives you warnings like this.
How dim? There are several possible answers. First, the output of the light coil is directly related to the engine rpm. Second, if the regulator/rectifier is not functioning properly, the lights can be dim. Third, if you have a poor ground connection the lights will be dim.
If your interior lights are dimming, either your battery or starter could be failing. You should have your car checked.