California Signals, Horns & Headlights Rules
Proper use of signals, your horn, and headlights is essential for safe driving and a critical part of the California DMV knowledge test. These rules exist to keep all road users informed and reduce collisions.
Turn Signal Rules
You must signal at least 100 feet before turning on regular roads. On a freeway, signal at least 5 seconds before changing lanes. Always signal even if you don't see other vehicles nearby — cyclists, pedestrians, and drivers you haven't spotted yet need that information too.
Horn Use
Your horn should be used to avoid collisions or warn others of a hazard — not to express frustration or greet friends. On narrow mountain roads where you cannot see at least 200 feet ahead, you should use your horn to alert oncoming traffic before proceeding around a blind curve.
High Beam & Low Beam Rules
Dim your high beams within 500 feet of an oncoming vehicle, and within 300 feet when following another vehicle. It is illegal to drive using only parking lights — they are for parking, not driving. Use headlights whenever visibility is reduced, including during rain, fog, or dust.
Key Rules at a Glance
- Signal before turning (regular road): At least 100 feet in advance
- Signal before lane change (freeway): At least 5 seconds in advance
- Dim high beams for oncoming traffic: Within 500 feet
- Dim high beams when following: Within 300 feet
- Parking lights while driving: Illegal — not a substitute for headlights