Help with Relay

[LightCrazy]

OK. I am not new to auxuliary lighting or electronics, but have a question. In PA it is legal to use fog lights in place of low beams in conditions of fog, snow, rain, etc., if the low beams actually cause too much glare. I have my fog light relay hooked up so I can turn the fog lights on and off but the parking lights have to be on to power the switch. How do I wire the circuit so the fog lights work with parking lights and low beams, but turn off when the high beams come on? Almost every new vehicle and even my older 87 mustang gt was wired like that. Can someone give me some input?? Thanks. I cant wait to get my 500FF's!!! NOTE: I still want the fog lights to work with just the parking lights on.

 

[krutj]

What vehicle do you have? I'm a Jeep guy and may be able to help. Sounds like you have the fog harness/relay running off the parking lights? yes? Just move it to the hot side of the headlight low beam relay, parking lights come on with the headlights, so by moving the fogs to the low beam relay, should do it.

 

[LightCrazy]

I have a 97 Blazer S-10. I know I can tap the low beam wire, I was just trying to figure out how the manufacturers rig it so fog lights will work with just the parking lights or also low beams, yet turn off when you switch the high beams on. Maybe it is more than just a relay that is involved.

 

[krutj]

I have a 97 Blazer S-10. I know I can tap the low beam wire, I was just trying to figure out how the manufacturers rig it so fog lights will work with just the parking lights or also low beams, yet turn off when you switch the high beams on. Maybe it is more than just a relay that is involved.

I see, won't using the low beam relay do this? ( or low beam/parking light relay) Have you tried it? I've got two aftermarket harnesses on my Jeep JK and I have to fire the relays separately, they both don't fire from one relay. Don't your low beams disengage when you fire the high beam?

 

[LightCrazy]

I can check the wiring diagram and check tapping the low beam relay. The blazer just has the single sealed beam light on each side, and the low and high beams are not on at the same time. Maybe that will let me use the fogs with the parking lts and low beams only. I'll post what I find out.

 

[krutj]

I can check the wiring diagram and check tapping the low beam relay. The blazer just has the single sealed beam light on each side, and the low and high beams are not on at the same time. Maybe that will let me use the fogs with the parking lts and low beams only. I'll post what I find out.

Good, let me know what you find out. I also saw your thread asking about Hella 500ff fog lights, I ran a set for three years, they're a decent inexpensive light and work well as a fog light, very diffused beam so you are not going to get any distance. For the money, they aren't bad.

If you would like to hear how to make your own lights, let me know, this can be done for under $200 and they are amazing....

 

[-Virgil-]

It's very easy to rig up a relay so the fog lamps can be used with parking lights or with low beams but not with high beams. The terminals on the relay are 85, 86, 30, and 87. 85 is your trigger positive, connect it to +12v. 86 is your trigger negative, connect it to a dashboard switch, then run from the other pole of the dashboard switch to the vehicle's high beam feed wire. 30 is your load input, connect it by way of a fuse to +12v. 87 is your load output, goes to the fog lamps.

This way the coil of the relay has a path to ground (through the high beam filaments) whenever the switch is thrown except when the high beams are on.

 

[LightCrazy]

THANK YOU!!! I knew there had to be a way to do it. I will try it tomorrow morning and let you know how it goes.

 

[LightCrazy]

see next reply

 

[LightCrazy]

Sorry about this posting confusion.
If I have this right... 86 on the relay goes to switch- either the feed input or to relay terminal. other terminal on switch to high beam positive? This way when fog light switch is on relay gets a ground- when hi beams come on that ground disappears and becomes power instead. 87 on relay to fog lights. 30 on relay fused to battery. 85 on relay goes to parking lights positive to give relay "trigger positive /power".

Thanks. I have never wired a relay getting power and grounds like this. Itlooks like you are just manipulating where in input triggering power to coil comes from, and where the other side of the coil gets its ground. so its ok for both sides of the coil- 85 and 86 to receive + power once the high beams are turned on?

 

[LightCrazy]

YOU DID IT!!!!!! NOW... the fog light switch is grounded so the switch will illuminate when power is on to the fog lights - but... now that the switch is between the relay and the high beam +, the light is off when the fog lights are on, and on when the high beams are on killing the foglight relay ground and turning them off. you know. SO since I will be able to tell the fog lights are on anyway, should I just disconnect the fog light switch ground so that the light is not opposite and playing games with me?? Thanks Scheinwerfermann- you are great!!!

 

[-Virgil-]

so its ok for both sides of the coil- 85 and 86 to receive + power once the high beams are turned on?

Yes, that is electrically identical to neither side receiving power.

 

[-Virgil-]

YOU DID IT!!!!!! NOW... the fog light switch is grounded

How/where? There should be no separate ground specifically for the fog lamp switch.

the light is off when the fog lights are on, and on when the high beams are on killing the foglight relay ground and turning them off.

Is it an LED or a bulb in the switch?

 

[Alaric Darconville]

NOTE: I still want the fog lights to work with just the parking lights on.

If the fog is often THAT thick that even low beams cause too much backscatter, I sure hope you've got a good rear fog lamp, too! I also hope you use the fog lamps to help you get off the road as far as you can before you get rear-ended! :)

 

[LightCrazy]

The switch is a Dorman LED Rocker, 84840.. The top terminal goes to ground (under dash), the middle terminal is supposed to go to the relay/lights, and the bottom terminal is the feed power from parking lights or in this case to/from the high beam positive wire.

 

[LightCrazy]

WELL, now something is not right. I just drove my vehicle, and the fog lights no longer work with the parking lights like they did earlier, and I am losing voltage someplace. I disconnected some wires and both fuses from the battery to each fog lt and driving lt relay so my car starts later. Anyone have any ideas? I had the trigger from the parking lights and the lead to the switch and high beam positive wire on either side of the relay. Relay was powered from the battery, and the wire to the lights were both left "as is" when I mad the change. I don't suppose it matters what side of the relay the trigger from the parking lights and the ground through the high beam positive wire were??

 

[-Virgil-]

The switch is a Dorman LED

In that case, swap the positions of the two wires connected to the middle/bottom terminals and see if that fixes the indicator light.

It's not clear from your 2nd posting (#16 in this thread) whether your fog lamps were working correctly with the new switch/relay hookup and now are not, or if they have never worked correctly with the new hookup.

 

[LightCrazy]

I did your hookup and tested them in the driveway. The fog lights came on with the parking lights and low beams, and turned off when I switched on the high beams. the only thing I noticed was that the LED indicator light built into the fog light switch only came on when the high beams turned on. The driving lights worked correctly with the high beams only- but instead of just the LED on the driving light switch illuminating with the hi beams, the fog light switch illuminated also. could that be because I split the positive wire from the high beams to the driving light switch to also serve as the ground for the fog lights like you said? I dont see how two seperate wires from the positive high beam wire would be any different. Right now all wires but the grounds on the switches are disconnected, and the fuses are pulled from battery 12 volt power to the relays so I don't drain my battery. Should we try again- the hookup seems to make sense, or should I just tap the low beam positive wire for the fog light switch and the high beam power for the driving lights and skip using the fog lights with the parking or low beams? This should not be that hard.

 

[LightCrazy]

More help with fog lights

Ok I have figured out how to get my fog lights off with the hibeams. If I want them to bea able to be on with only the low beams and not parking light- I am hitting a wall. My 1997 blazer has the single sealed beam headlp on each side. If I tap the low beam wire at the lamp, it has enough voltage in it because of the DRL that the fog lights can be turned on. How can I tap just the power for low beams without this erroneous voltage?

 

[Alaric Darconville]

Re: More help with fog lights

You should update the old thread (http://www.candlepowerforums.com/vb/showthread.php?331044-Help-with-Relay) and ask a moderator to close this (or merge this with that thread).