Daytime Running Lights without resistors

I was just reading some varying posts about DRLs and thought I'd post my 2 cents.

Most of the info here is based off of wiring info I've gotten from my '02 Sunfire; however it would be reasonable to think that the same info would apply to other vehicles which use only the headlights as the DRLs.

On this car, the headlights are wired as follows:

Each bulb has its own constant 12v power supply.
The low beam and high beam ground wires from each bulb(this car has one bulb for both) are common, and go to the headlight switch.
The switch grounds either the low or the high beams, depending on the position of the dimmer.

The DRL relay is wired as follows:
87a - constant 12v supply for one of the two bulbs
87 - ground
30 - goes to the power side of the bulb and nothing else
85 - DRL relay control wire(from the BCM or the instrument cluster)
86 - switched 12v

Whenever the relay is activated, it completes the circuit; but it does so with the bulbs in series, which increases the resistance, and results in the reduced brightness, without the need to add additional resistors into the circuit.

You can use this information if you are looking to add DRLs to headlights or foglights; obviously, you should check the vehicle's wiring first, but this setup should work. If your lights have switched 12v instead of switched ground, then you could hook up 87a to ground, 87 to 12v, and 30 to the ground side of one bulb in the circuit.

Questions? Complaints? Comments anyone?

better than burning off power in a resistor