Automotive Lighting FAQ

What does DRL mean?

Daytime running lights. If a vehicle has DRL, the main intension is that as long as the engine is running, lights will come on automatically.

Where is DRL usage mandatory?

Canada and fourty something countries under ECE regulations. Not required in the US, which means that some vehicles has and some don't, which worsens the saftety standpoint. ECE regulations also require parking and tail lights to be operational. Canada has not adapted that portion.

What are the pros of DRL usage?

Studies showing that collision rates decreases.

Oncoming traffic will see you better.

What are the cons of DRL usage?

Masking. Bright driving lights with the same color as daylight will make your a car invisible viewed against a sunrise/sunset or during an overcast day (very high Kelvin ambient light). Another example of masking is one dark car in a row of many with DRL.

Studies showing that collision rates increases - pretty confusing, ha?

NHTSA website at Docket 4124 has alot of DRL complaints.

What about low beam projector HID DRL?

Oncoming trafic will se you even better when they sparkle in all sorts of colors, and it definatly looks "cooler" than orange halogen on "half speed".

What is the biggest challenge with todays DRL systems?

Allmost non existing regualtions. Some vehicles DRL systems are too glaring, even at daytime Others have shortlived DRL units. There is a need for uniformity of placement, intensity, and tamper-resistance incorporated into DRLs. As it is right now, it's a mess out there, with every kind of daylight lighting.

How does high beam DRL systems with lower intensity work?

Low beam DRL systems are not very common in North America, however, it is perfectly legal. High beam DRL systems are very common. The main reason for using high beam is simply a marketing/safety/relibility thing from manufacturer. Since full power high beams in general are used 30% and low beams are used 70%, automaker can make bulbs last longer by combining high beam with DRL function.

Tecnically, a resistor could be placed in series with bulb to lower voltage and therefor output, but it would not be possible to go below a certain voltage. Below around 10Volts, bulb does not get hot enough and start making inside of bulb glass smoked, which of course is not good. The most common solution to this is to send squared vawed pulses with a vawe length of about 12ms of 12V hight. By varying the time off in comparison to time on, the desired output can be achived. As an example, if you have a 55W bulb, and have 1:1 relationship, it would give half the output. In most realistic cases, squeare vawe is more on than off, giving out 60-80% of full wattage.

Where can I buy aftermarked DRL units?

They are available at Canadian Tire/Pep Boys, build quality is average but they are cheap - less than 15 bucks. Also Ford and GM have available kit for the aftermarked. See http://www.pacificinsight.com/aftermarket/after_daytime.htm for information.