What is a requirement for the high beam indicator on a vehicle?

The requirement for the high beam indicator on a vehicle is that it should work properly when required. This means that drivers must be able to rely on the indicator to properly signal whether the high beams are activated or not. A functioning high beam indicator is crucial for safe driving, as it helps prevent the blinding of other drivers while ensuring that the vehicle's lighting system is working as intended. This aspect is particularly important for maintaining visibility in various driving conditions, thus contributing to overall road safety.

The other options do not adequately capture the core requirement for the high beam indicator. For instance, while color codes for indicators may vary, the actual requirement is the proper functioning of the indicator rather than its color. Additionally, the status of the high beam indicator is not optional based on the age of the vehicle; modern safety standards apply universally. Lastly, there is no general requirement stating that the high beam indicator must automatically turn off, making the operational state of the indicator far more critical.