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"Driving lights" as Daytime-use running lamps

3K views 47 replies 9 participants last post by  csouers 
#1 ·
I'm pondering around the idea of throwing on a pair of cheap driving lights from wal-mart or someplace to run with my marker/parking lamps.

My idea is for them to come on ONLY when the parking lights are one, but not with the headlights on. This way they sort of act as DRL's so I can save my headlight bulbs. I have the factory fog-light switch in my XJ, just took off the lights when I hit a deer last May (one was broken into pieces and the other had a burnt bulb. they were lights from k-mart)

I believe that I would have to relay the switch as I'm pretty sure it is not relayed from the factory. As far as wiring it to come on with the parking lamps and turn off with the headlights, I'm not quite sure how I'd do that.

Keep in mind, I'm not going to put big expensive lights, as this is really only for safety when weather conditions are so so.
 
#2 ·
in my state is legal to run fog lights anytime the brights are not being used on the headlamps.

i'd just wire up a switch and away you go. I guess you could put a relay into the parking lamp circuit or something so it would switch on the fog lights automatically if you wanted. the problem is you can't turn on headlights without parking lights so you would have to manually switch the relay off somehow for when you were running with headlights.

Planned: Entire new exhaust with flexible exhaust manifold
Not to jack your thread...but flexible? Where can I get this?
 
#3 ·
#4 ·
bumparoo

I know to hook the aux lights to come on with the parking lights but not how to make them go off with the headlights. I suspect that would require some other kind of electrical unit that I'm not aware of.
 
#5 ·
Fused main battery power to a changeover relay ( the same relay as used for most stuff in an XJ )

Battery power out from the change over relay to a normal relay.

Battery power out from the normal relay ( activated by the park light wiring ) to the lights.

Having a connection from the low beam circuit to the change over relay will deactivate the power supply at the change over relay when the headlight switch is fully extended.

Just make sure you understand the terminal connections in the links below.

There is probably other ways to do it as well.

Relay_Info

Relays
 
#6 ·
Automatic/daytime running lights are pretty pointless, especially considering your geographic location. And even if you were far enough north to require use of headlamps during daytime hours, I'm still unsure why it would be so difficult to just switch on the lights.

And it seems to me that you would save yourself a ton of time just turning on the headlights. You're going to have to go through the motion anyway to turn on the parking lights, why not just pull the extra 1/8" to turn on the headlights? If that's too much effort every time you get in the truck, why not relay the headlamps to come on with the ignition?
 
#7 ·
The point of all of this is to save my headlight bulbs. It's not that I'm too lazy to pull the extra length.

Safety is the key here. The more visible you are in hazardous conditions, the better. I like to use my lights when it's raining or gray outside. I just feel a bit more safe that way.
 
#9 ·
You can actually do it with 2 relays. These relays can be bought from any automotive shop, radio shack, or a specialty electronic store.

I'm trying to think of a good way to draw it out because I actually suck with computer graphics but I could if you want me to, send me a PM if the following explanation doesn't cover what I'm trying to convey.

The first relay would be spliced into your running light switch so when you turn it on, it triggers the relay and activates your lights. From that relay, take it to the NC loop of another relay that is triggered from your head lights (when they're on, it would trigger the relay, thus breaking the circuit).

I could draw a diagram in a few minutes on paper, but would need a good way to get it on the computer to post it.

Again, I could do it with MSPaint if needed. Let me know.
 
#11 ·
Sorry, my knowledge of electronics in general (and relay logic specifically) far surpasses my knowledge of vehicles as of this date and time.

A NC loop is a normally closed loop. Basically, when the relay is sitting in it's normal, untriggered configuration, this loop allows current to pass. A NO loop (normally open) is a loop that won't allow current to pass until triggered by a voltage applied to the trigger mechanism.

In the Diagram above, 86 and 85 are the trigger circuit (wired in such a way that when switch is thrown, it triggers the relay.

30 is known as the common (not to be confused with ground. it's called a common (c) because it's common to both the NC and NO loops). 87a is the NC loop because if the relay isn't triggered, 87a is allowing current to flow and 87 is the NO loop because it won't allow current to flow until the trigger is applied. (this actually changes depending on the application, but we'll use this definition for this example because it's the most common.)

If you were going to use that relay to do what you wanted, you'd need 2.

The first would use the switch for running lights to trigger either 86 or 85 depending on which side is positive and which is ground and whether your switch is switching positive or ground (going a little deep here).

30 would go to your battery + termanal (the lights will be grounded independantly so we'll switch the positive side.

87a be left blank and 87 would go to the other relay.

on the 2nd relay, 86 or 85 would be wired to your head lights (so when they are on, they trigger the relay) and 87 from the other relay would go to 30 with your lights being wired into 87a and 87 would be blank. That way when your head lights come on and trigger the relay, it would break the circuit.
 
#12 ·
That's very descriptive. So if I wanted to switch to enable/disable the lights all together, would that require ANOTHER relay? It seems to me that it would. 1 for the switch itself, another from a parking lamp circuit, and another from the headlamp circuit.

Also, from what you're describing, I wouldn't need a relay with the 87a terminal. I could just get on with the 87 only and be okay?
 
#13 · (Edited)
Actually, the 87a circuit is used on the second relay to turn the lights off when your headlights are turned on.

If you wanted manual control over them to by pass the other circuits, you would need two switches added to the configuration.

If you wanted to kill them regardless, you'd need a switch to interrupt the + to the battery that's being used to provide current to the lights regardless of the state of any of the

Switch A would be put in the line heading to 30 of your first relay above (this switch would be left on to run them as you want and off would kill them regardless of your current light switch.

Switch B would be used to turn them on regardless and would between + battery (assuming grounds at the lights) and tied into the wire coming from 87a and your lights, that way when you threw the switch, it would allow current to bypass the relays and run the lights regardless of the relay configuration.

It can get a little more complicated as you add different configurations. In the above descriptions, Switch B will turn the lights on regardless of the anything else. Switch A will only turn them off if Switch B is off, regardless of the state of your current light switch.
 
#16 ·
The idea you posted before is starting to form in my head.

I'm assuming when you are saying switch a and b that you are describing SPST switches, instead of SPDT.

I have an extremely similar setup on my reverse lights. I have a position to be on with the headlights, off completely, or with reverse lights(regardless of headlight power) That only require one switch, due to the Double Throw mechanism.
 
#17 ·
disclaimer:

The above configurations were done after a rough day at work while drinking more then 1 budlight. I've run over it in my head but have yet to draw it out. I tried on MS paint but the symbols for a battery and a light made me realize that I was in for more then I expected. I would be more then happy to draw it out on paper and send it to anybody who wanted it.

If you decide to do something like this, the wires running from your + battery terminal need to be fused and I recommend having extra fuses on hand incase there is a mistake in my description and one blows. I'll be more then happy to trade PMs to help troubleshoot of if worse comes to worse, we can trade phone numbers and I can talk you through it.
 
#18 ·
You're correct, I'm talking about SPST switches.

TBH, when talking about switches, they are usually SPST, relays come in a SPDT configuration where a single trigger actually throws 2 sets of contacts (2 c's, 2 NC's and 2NOs). This is different then a triple position switch.

The above configuration may be done with a single triple position switch, I'd have to give that some thought.

SPST stands for Single Pole, Single Throw (where the pole is your trigger) and SPDT stands for Single Pole (trigger) Double Throw (it throws or moves 2 sets of contacts.) It may be different in automotive, but this is the accepted use in electronics.
 
#21 ·
Those driving lights you want to use .... Do you intend to use them as running and night time driving lights ???

Coz you can do all your talking about without any switches ...

If your going to fit a switch for them .... just use it to turn them on & off whenever you want ... a 20amp fuse, 30amp wire and a 30amp switch will do it as long as your wiring doesnt rub through somewhere.
 
#22 ·
I am planning on using the SPDT switch just to have the control. I would only use the lights as daytime running lamps. In theory, I wouldn't even need a switch, but I want that extra measure of flexibility. We all like to play right? :thumbsup:
 
#27 · (Edited)
I am planning on using the SPDT switch just to have the control. I would only use the lights as daytime running lamps. In theory, I wouldn't even need a switch, but I want that extra measure of flexibility. We all like to play right? :thumbsup:
Yep ... always fun.

Try this for thought ... Its a bit more detailed than my original post with the links ;)

Change Over Relay Connections

30 .... fused power from battery
85 .... connection to Lo Beam
86 .... connection to battery earth
87 .... insulated spade terminal only / no wiring
87a .. outgoing power for lights to terminal 30 on the normal relay

Normal Relay Connections

30 .... power from change over relay terminal 87a
85 .... connection from park light via an on/off switch
86 .... connection to battery earth
87 .... Driving Light 1
87 .... Driving Light 2

Driving Lights will turn on when park lights and/or Hi Beam are selected,
Driving Lights will turn off when Lo Beam is selected,

The switch between the park light wiring splice and terminal 85 on the normal relay will also let you turn them off any time you want.

Earth your lights back to the battery too .... Its the better way to go instead of rattly self tappers in the bodywork.

and my disclaimer is ....

Your the one with the sidecutters / tape / soldering iron and wires in your hand ... not me ..... :laugh:
 
#25 ·
Never mind. This wouldn't work. Because even with manual on and headlights on, the relay b will still kill the lights because it sees that the headlights are on. This would almost certainly require the DPDT switch you were talking.
 
#26 ·
where the problem lays with trying to use a single 3way switch instead of 2 switches is the switches don't have a common point. I may be able to do it, given a little more time, but you'd def need a 3rd relay, just not sure how'd it be wired in. Again, I'd have to look at it and do some more deep thinking.
 
#28 ·
Ok, how about this one?



Power comes from the battery to the first relay. It is controlled by the ignition coming on. Wire it into the power distribution panel to something that only turns on with the ignition (wipers, heater, rear window defogger, etc).

This supplies power to the second relay, which is reverse controlled (through connection 87a) by the headlights coming on. Tap into the low beam wire for this.

Power then goes to the fog lights. Connect at the fog lights in parallel to the existing wiring (which has a factory relay already in it). The factory foglights only come on with the low beam headlights. And your "DRL" circuit cannot come on with the headlights, so no cross contamination of circuits there.

No switch required. Fully automatic.
 
#30 ·
Very nice diagram. That is more for them to run when the headlights aren't on, regardless of running light mode. I would use the same type diagram, with maybe relay or two more and a switch. I think with a good understanding of what's going onnow, I can design the system to my needs. I'll draw up a diagram and post it up once I get home.
 
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