daytime running light
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=134235
Printed Date: July 13, 2025 at 5:28 AM
Topic: daytime running light
Posted By: eg6-sir
Subject: daytime running light
Date Posted: May 19, 2013 at 5:15 AM
I want to install the day time running light for my car .I want to ask if I want to install the 12v led daytime running ,but I need that to turn off when the low beam is turn on.I have been find out the 12v+ when i start the car but How can I connect the wire if I use the relay to make it work?Anyone can help or can show me how to use the relay.
Thanks you
Replies:
Posted By: oldspark
Date Posted: May 19, 2013 at 6:17 AM
Connect the LED- to the low beam's switched +12V.
The DRL LEDs will then normally GND thru the low beam load or filaments.
If the low beams are on, then LED- is +12V, hence 0V across the DRL LEDs and they'll extinguish.
Posted By: eg6-sir
Date Posted: May 19, 2013 at 6:25 AM
Thanks but I need to use a relay to make it works couse those are the CCFL Light so must use the relay to cut off the power when the low beam is on.I don't know how to connect the relay and which relay does I use?
Posted By: oldspark
Date Posted: May 19, 2013 at 9:48 AM
Same connection, but to the relay coil instead.
IE - switch +12V to relay 86; 85 to low beam filament switched +12V.
30 & 87 from fused +12V to CFL (or whatever) +12V.
Any typical 12V SPST (pr SPDT) automotive relay - typically 30A rated - as long as it handles the running light current (which is probably only a few Amps).
Posted By: howie ll
Date Posted: May 19, 2013 at 4:41 PM
This is how you do it.
You use a latching relay that's triggered by the starter wire.
The ignition on shutdown goes to ground which will turn it off.
The second relay passes the voltage through to the DLRs but "disconnects" as soon as you turn on the low beam lights.
The Omron latching relay is readily available from Farnell or Mouser in North America. G6CK21124-US12DC.
It's a DPDT but you will only use one side as a SPDT.
Here's how:- dlr.bmp------------- Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
Posted By: howie ll
Date Posted: May 19, 2013 at 4:43 PM
I've had a long working day today, it's 11:00pm here and I can't be bothered to explain the circuit.
I'm sure Oldspark can explain it for you, the problem is that English isn't your first language is it?
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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
Posted By: eg6-sir
Date Posted: May 19, 2013 at 6:06 PM
Thanks you guy . I can find the constant 12v+ which is when I start the car also I can find the low beam wire.but I need you guy to show me the diagram how to connect it with the relay!what I need to connect is I need the CCFL light turn on when car start and turn off when the low beam turn off.
Thanks you
Posted By: howie ll
Date Posted: May 19, 2013 at 6:17 PM
No 12v constant means it's on ALL THE TIME not just with ignition, if you followed posting rules you'd have given us year, make and model.
I've already given you the complete diagram but since you aren't listening why help?
-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
Posted By: eg6-sir
Date Posted: May 19, 2013 at 6:24 PM
I have the 1992 Honda civic thanks
Posted By: howie ll
Date Posted: May 19, 2013 at 10:23 PM
Your starter wire is BLACK/ white, your ignition BLACK / YELLOW, as for your low beam, test.
-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
Posted By: howie ll
Date Posted: May 31, 2013 at 6:05 PM
Actually I'm being silly, just connect the POS to an ignition source and the NEG to your headlight low beam.
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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
Posted By: eg6-sir
Date Posted: June 01, 2013 at 5:47 AM
Thanks do you have the diagram to show how to connect to the relay
Posted By: howie ll
Date Posted: June 01, 2013 at 11:05 AM
You won't need one, red to ignition, black to low beam headlights.
I did a set on my car yesterday.
Takes it's power from ignition, when headlights are off, that low beam is "sitting" on ground completing the circuit.
When you go to low beam headlights, since your power AND ground wires are at 12 volts, the circuit is broken.
-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
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