Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post

Piwoslaw · 01-22-2012, 03:48 PM

In many parts of the world driving with your lights on during the day is mandatory for part or all of the year. Also, many drivers keep their lights on, even if they are not required to, for safety reasons. Unfortunately, the extra electrical load (150-200W) increases fuel consumption.

Daytime running lights, especially LEDs, can provide the same visibility while consuming much less power because:

They produce only enough light to make the vehicle visible, not to illuminate the whole road ahead,
Only the DRLs are on, while the position, dashboard, and license plate lights stay off, since they are not needed.

A pair of LED DRLs can use as little as 10 watts. In the Europe, all 2012 model year cars must have OEM fitted DRLs.

So, I've started this thread to help make it easier to install DRLs, especially the from the electrical side, which may be a little tricky. European law says that DRLs must turn on when the key is in the position which allows the engine to be operational (though the engine itself need not be turning), and must turn off when the headlights or high beams turn on (except when only flashing the highbeams). Here is a diagram of how my DRLs are wired to fulfill these requirements, and a few extras:

On the left is an ON-OFF-ON switch, the middle pin gets +12V from the accessories wire (off when engine is off). Position II (AUTO) routes through the relay, which disconnects the DRL when the headlights turn on. Position I (ON) bypasses the relay directly to the DRL, so they do not turn off when the headlights go on.
The LED at the top is mounted in the cabin to let the driver know if the DRLs are lit up.

The bypass is not really needed, but may come in handy (for example as foglights). You may want a way to turn the DRLs off, since there are places where using them is illegal (or at least was a few years ago), for example on highways in Portugal, or in Greece within city limits. I'm not sure if this is still the case, if not then the switch itself (and even the cabin LED) can be omitted for simplicity.

In my cockpit you can see the small LED (not lit) above the I-0-II rocker switch on the right:

01-22-2012, 03:48 PM	#1 (permalink)
Piwoslaw aero guerrilla Join Date: Oct 2008 Location: Warsaw, Poland Posts: 3,705 Svietlana II - '13 Peugeot 308SW e-HDI 6sp 90 day: 58.1 mpg (US) Thanks: 1,278 Thanked 731 Times in 464 Posts	How to wire DRLs In many parts of the world driving with your lights on during the day is mandatory for part or all of the year. Also, many drivers keep their lights on, even if they are not required to, for safety reasons. Unfortunately, the extra electrical load (150-200W) increases fuel consumption. Daytime running lights, especially LEDs, can provide the same visibility while consuming much less power because: They produce only enough light to make the vehicle visible, not to illuminate the whole road ahead, Only the DRLs are on, while the position, dashboard, and license plate lights stay off, since they are not needed. A pair of LED DRLs can use as little as 10 watts. In the Europe, all 2012 model year cars must have OEM fitted DRLs. So, I've started this thread to help make it easier to install DRLs, especially the from the electrical side, which may be a little tricky. European law says that DRLs must turn on when the key is in the position which allows the engine to be operational (though the engine itself need not be turning), and must turn off when the headlights or high beams turn on (except when only flashing the highbeams). Here is a diagram of how my DRLs are wired to fulfill these requirements, and a few extras: On the left is an ON-OFF-ON switch, the middle pin gets +12V from the accessories wire (off when engine is off). Position II (AUTO) routes through the relay, which disconnects the DRL when the headlights turn on. Position I (ON) bypasses the relay directly to the DRL, so they do not turn off when the headlights go on. The LED at the top is mounted in the cabin to let the driver know if the DRLs are lit up. The bypass is not really needed, but may come in handy (for example as foglights). You may want a way to turn the DRLs off, since there are places where using them is illegal (or at least was a few years ago), for example on highways in Portugal, or in Greece within city limits. I'm not sure if this is still the case, if not then the switch itself (and even the cabin LED) can be omitted for simplicity. In my cockpit you can see the small LED (not lit) above the I-0-II rocker switch on the right: __________________ e·co·mod·ding: the art of turning vehicles into what they should be What matters is where you're going, not how fast. "... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell [Old] Piwoslaw's Peugeot 307sw modding thread Last edited by Piwoslaw; 01-23-2012 at 01:16 AM..