Wiring aftermarket DRL lighting so that they turn on during the day but off at night….

[corneileous]

….without having to use the factory DRL wires that go to the headlights for the premium projector headlight trucks.

Right now the white DRL’s in my aftermarket foglights and the white DRL’s in my switchback DRL/turnsignal light bars that I have mounted above my front tow hooks are wired to the factory DRL wires which is fine but I’m just not real crazy about how they don’t turn on until after the transmission is shifted out of park.

I’d really like for them to turn on as soon as the engine is fired up like how I had them wired the first time when they were connected to the ignition coil circuit in the fuse box with a fuse tap but I didnt like the DRL’s being on at night when the headlights were on. That was the only downside to having them wired like that. Now, if I could find a circuit in the fuse box that would go dead as soon as the headlights were turned on, that would be wonderful but I don’t think such a circuit exists so is there another option aside from just wiring those lights to a switch so that as soon as I turn the headlights on, I would just turn off the switch and then have to remember to turn it back on?

Thanks.

 

[diymirage]

hook them up as the first time only this time, install a relay in between the power and the lights

(power to 30, ground to 86, wire to the lights to 87)

this should be on as soon as the 30 wire is hot (so used a keyed postive for that)

then you find a wire that is hot when the lights come on, tap into the headlight, or an interior light and run that to the 85 post

(Or since you mentioned fuse taps, see if there is a fuse that gets hot when the headlights come on, and put a tap on it)

now, this should be a "normally closed" system, meaning when there is no power to the 85 post, the power from the 30 goes to the 87

but once you put power to 85, it should open the switch and kill the lights


Then, when you kill the headlights, the relay will revert back to its "normally closed" state and turn the DRLs back on

 

[corneileous]

hook them up as the first time only this time, install a relay in between the power and the lights

(power to 30, ground to 86, wire to the lights to 87)

this should be on as soon as the 30 wire is hot (so used a keyed postive for that)

then you find a wire that is hot when the lights come on, tap into the headlight, or an interior light and run that to the 85 post

(Or since you mentioned fuse taps, see if there is a fuse that gets hot when the headlights come on, and put a tap on it)

now, this should be a "normally closed" system, meaning when there is no power to the 85 post, the power from the 30 goes to the 87

but once you put power to 85, it should open the switch and kill the lights


Then, when you kill the headlights, the relay will revert back to its "normally closed" state and turn the DRLs back on

Hmmmm…. You might just be on to something here. I guess it just all boils down to knowing how relays work…lol.

But anywho, are all 4-post relays the same? After looking at this one, it’s saying ground goes to 85 but you’re saying to put the ground on 86, a headlight wire tap to 85 and then 87 would be power to my lights with the trigger wire for daytime use would go to 30 which is from the ignition coil fuse that I used before….

 

[crash68]

this should be a "normally closed" system, meaning when there is no power to the 85 post, the power from the 30 goes to the 87

The normally closed terminal is 87a.

are all 4-post relays the same?

Need to use a SPDT relay that has the fifth terminal 87a

 

[diymirage]

Hmmmm…. You might just be on to something here. I guess it just all boils down to knowing how relays work…lol.

But anywho, are all 4-post relays the same? After looking at this one, it’s saying ground goes to 85 but you’re saying to put the ground on 86, a headlight wire tap to 85 and then 87 would be power to my lights with the trigger wire for daytime use would go to 30 which is from the ignition coil fuse that I used before….View attachment 543821

I was thinking of a 5 post relay, those can be wired up as normally closed, or normally open

To the best of my knowledge, all 4 post relays are normally open, which wouldn't work for you

As far as how they work, think of a relay as a switch, but instead of using your finger to activate it, you use an electrical signal

 

[corneileous]

The normally closed terminal is 87a.

Need to use a SPDT really that has the fifth terminal 87a

So then I'm assuming this is what I need correct? And hopefully this is the same thing? My local Oreileys has one.

So if thats what I need then what wires would go where? Keep in mind I'd still be using the ignition coil circuit in the fuse box which I guess which would continue to power the lights during the day when the headlights are off and I suppose in order to make the lights turn off when the headlights come on, I would use the marker light wire which is close to what @diymirage suggested, correct?

 

[crash68]

So then I'm assuming this is what I need correct? And hopefully this is the same thing? My local Oreileys has one.

Either relay will work.
You'll wire the DRL power using the #30 and #87a (NC contacts) and then wire the coil(85 & 86) to the marker or headlights. That will turn the DRLs off when the marker or headlights are turned on.

 

[corneileous]

Either relay will work.
You'll wire the DRL power using the #30 and #87a (NC contacts) and then wire the coil(85 & 86) to the marker or headlights. That will turn the DRLs off when the marker or headlights are turned on.

OK, I'm confused.... the wires coming from my DRL lighting would go to both terminals 30 and 87A?

Not understanding the last part, either.

 

[crash68]

OK, I'm confused.... the wires coming from my DRL lighting would go to both terminals 30 and 87A?

Not understanding the last part, either.

Using the example picture you posted above but instead use terminal 87a. The red would still go-to a fuse, the blue wire to the DRLs. The green and black wires would get wired to the running lights.

Wired this way will turn the DRLs off when your running lights are on.

 

[corneileous]

Using the example picture you posted above but instead use terminal 87a. The red would still go-to a fuse, the blue wire to the DRLs. The green and black wires would get wired to the running lights.

Wired this way will turn the DRLs off when your running lights are on.

Ok so let me get this straight.... The wire that goes to the DRL lighting would go to 87, the power supply wire coming from the ignition coil fuse tap in the fuse box (that I used the first time) would split off and go to both 30 and 87A and the wire coming from the marker lights would split off and go to both 85 and 86?

 

[crash68]

The wire that goes to the DRL lighting would go to 87,

NO..do not use the 87 terminal at all.
The DRL wire goes to 87a and the supply power wire from the fuse tap goes to 30.
85 goes to the marker light, 86 is the ground (best to use the same ground as the marker light).

 

[corneileous]

NO..do not use the 87 terminal at all.
The DRL wire goes to 87a and the supply power wire from the fuse tap goes to 30.
85 goes to the marker light, 86 is the ground (best to use the same ground as the marker light).

Ok, I think I got it now…lol. I guess it was the way you were explaining it that was confusing the heck outta me….lol.

But what do you mean by using the same ground as the marker lights? How would I do that? In order to get a wire from the marker light, I was just gonna pull the driver side headlight out and tap into the marker light circuit to run to the relay and just ground the relay to the chassis.

 

[crash68]

But what do you mean by using the same ground as the marker lights? How would I do that?

There is two wires(positive and negative) that go to any light bulb, same goes for the marker light. You'll run both to the relay (one to each terminal, not both together)
Technically the marker light will have three but one of them is the turn signal, don't use that one.

 

[corneileous]

There is two wires(positive and negative) that go to any light bulb, same goes for the marker light. You'll run both to the relay (one to each terminal, not both together)
Technically the marker light will have three but one of them is the turn signal, don't use that one.

Well I guess I could see that if I had the plain reflector headlights but I have the premium projectors so then would I just tap into the white wire with orange tracer that goes to terminal 2 for the marker lights but which ground would I use? There’s 2- one that goes to terminal 9 and one that goes to terminal 13.

 

[crash68]

but which ground would I use? There’s 2- one that goes to terminal 9 and one that goes to terminal 13.

either one should work but unplug the headlight and see which one shows the least resistance between it and terminal #2.
Just taking a guess it will probably be #13.

 

[corneileous]

either one should work but unplug the headlight and see which one shows the least resistance between it and terminal #2.
Just taking a guess it will probably be #13.

So you’re saying to unplug the big wiring harness from the headlight, turn the marker lights on and then take an ohm reading between the marker light terminal and the two ground terminals to see which one has the least resistance?

But just outta curiosity, why is this way better than just running a ground wire from the relay to a good chassis ground?

 

[crash68]

So you’re saying to unplug the big wiring harness from the headlight, turn the marker lights on and then take an ohm reading between the marker light terminal and the two ground terminals to see which one has the least resistance?

But just outta curiosity, why is this way better than just running a ground wire from the relay to a good chassis ground?

Take the resistance reading on the headlight pins, this is to determine which ground is the one wired to the marker lights.
Being all the bulbs are monitored, using the headlight ground wire there's less probability of problems with false bulb out errors occuring.

 

[diymirage]

Take the resistance reading on the headlight pins, this is to determine which ground is the one wired to the marker lights.
Being all the bulbs are monitored, using the headlight ground wire there's less probability of problems with false bulb out errors occuring.

By that reasoning, wouldn't it make more sense to just ground it to the chassis or the battery ?

 

[crash68]

By that reasoning, wouldn't it make more sense to just ground it to the chassis or the battery ?

There have been members who have reported issues with wiring loads to a bulb then to a chassis ground.
In part it has to do with voltage biasing of the PWM circuitry that controls the lights on the truck. Where the ground path is referenced is important.

 

[bm02tj]

It sounds he want the DRL the moment he starts truck then off with lights
Pick up switch signal from HVAC output to switch relay for lights on then a second relay NC
and switch off with power from park light