Simple and cheap DRL using the highbeams
Posted: Thu Dec 06, 2007 12:20 pm
Sometimes I amaze myself. I was thinking about how I hate the lowbeams coming on with my key all the time especially during cold starts and got to thinking how I could cut down on the draw. I thought of wiring it to the park brake switch (might still do that) but then I started thinking about using a dimmed high beam for the DRL. 2 hours later I have it designed, installed and working and it is so stupidly simple and cheap.
Keep in mind I suck at math so I am not sure it draws any less amperage, but it is still cool.
I will add pics and a step by step in the wiki tonight but for the electrically inclined, here is the text version.
Buy a standard automotive 12v relay that is normally closed and when energized, closes a different circuit (dpdt????) basically any relay you buy from Lordco will have a 90% chance of being the one.
The terminals should be marked 85 and 86 for the relay control circuits and 30, 87, and 87a for the load circuit.
Remove the drivers headlight assy, cut the black ground wire that is for the highbeam bulb only. The side of that black wire that heads to the bulb connects to terminal 30 on the relay. Connect the other side of that wire (the side that goes to ground) to terminal 87a (the one in the center of the relay), connect a switched 12v that can handle the highbeam power to terminals 87 and 86. Now, the wire that is power for the lowbeams (I think mine is light blue or something), dont cut it but splice a wire off of it and connect that to terminal 85.
Under the dash, remove the Highbeam fuse (#6 from the top left when looking at the fuse box, 15amp I think)
Ok, that is as far as I have gotten. I need to get a diode today to finish the last step, which will be to put that diode in line with the fuse. I will probably remove the fuse box to do it and install the diode in the wire.
SO, now you have dim highbeams in DRL mode and when you turn on the headlights, the DRL's turn off. And if it gets dark enough that you happen to notice the highbeam indicator is slightly illuminated, (cant see it during the day) then perhaps it is time you turned on your headlights.
I will post up the steps with pics and a part# for the diode when I finish.
UPDATE: 15 amp diode is a bit hard to find in stock locally, I have one coming, should be here next week sometime, around $7, will post part# and order info when I am done.
Keep in mind I suck at math so I am not sure it draws any less amperage, but it is still cool.
I will add pics and a step by step in the wiki tonight but for the electrically inclined, here is the text version.
Buy a standard automotive 12v relay that is normally closed and when energized, closes a different circuit (dpdt????) basically any relay you buy from Lordco will have a 90% chance of being the one.
The terminals should be marked 85 and 86 for the relay control circuits and 30, 87, and 87a for the load circuit.
Remove the drivers headlight assy, cut the black ground wire that is for the highbeam bulb only. The side of that black wire that heads to the bulb connects to terminal 30 on the relay. Connect the other side of that wire (the side that goes to ground) to terminal 87a (the one in the center of the relay), connect a switched 12v that can handle the highbeam power to terminals 87 and 86. Now, the wire that is power for the lowbeams (I think mine is light blue or something), dont cut it but splice a wire off of it and connect that to terminal 85.
Under the dash, remove the Highbeam fuse (#6 from the top left when looking at the fuse box, 15amp I think)
Ok, that is as far as I have gotten. I need to get a diode today to finish the last step, which will be to put that diode in line with the fuse. I will probably remove the fuse box to do it and install the diode in the wire.
SO, now you have dim highbeams in DRL mode and when you turn on the headlights, the DRL's turn off. And if it gets dark enough that you happen to notice the highbeam indicator is slightly illuminated, (cant see it during the day) then perhaps it is time you turned on your headlights.
I will post up the steps with pics and a part# for the diode when I finish.
UPDATE: 15 amp diode is a bit hard to find in stock locally, I have one coming, should be here next week sometime, around $7, will post part# and order info when I am done.