I remodeling my wiring harness (completely out of the car and adding and subtracting wires as needed) and will probably have a series of issues - but currently I'm working on adding wiring for a future set of extra fog lights (vintage rally style mounted to the front bumper on brackets). The car and harness are '72 and wiring is already there for the stock fogs. The extras will only be run occasionally and so I'd like to put them on a separate circuit.
I have the front half of a '74 harness that I'm stealing wires, etc from. So from it I've pulled the late fog light switch, stock wiring and the stock relay that they are attached to. My question is how to add and power the relay to the original '72 harness .. any how that then attaches to the fuse panel? Any help appreciated, thanks.
.
Full Version: Adding EXTRA fog lights help?
I do not use "Fog" lights here in Hell.
You need them 2-3 times a year.
If I'm adding lights, they are "Driving" lights.
Put a pair of Hella Euro Drivers (not DOT legal) on a 240Z, ran them direct off of alternator feed through a Bosch relay. Flame throwers!
The customer said he couldn't really use them. He stated they lit up the road 1/2 mile away. Twice as far as the high beam which were "hot rodded" as well.
He was terrified of getting a ticket for them.
He does use them if there is no-one around.
You need them 2-3 times a year.
If I'm adding lights, they are "Driving" lights.
Put a pair of Hella Euro Drivers (not DOT legal) on a 240Z, ran them direct off of alternator feed through a Bosch relay. Flame throwers!
The customer said he couldn't really use them. He stated they lit up the road 1/2 mile away. Twice as far as the high beam which were "hot rodded" as well.
He was terrified of getting a ticket for them.
He does use them if there is no-one around.
If I was searching for a factory look and I did not have the rear window defroster, I’d use that circuit. That would be the forth relay socket on the relay board. It would use the same round relay. You’d want to check what amps are available on that circuit and how many amps the lights will draw. I would imagine that if the defroster was available on your year car that the wiring harness will have the wires for the switch leg in the cabin.
I also use the clear lenses (driving lights) on mountain roads. They have a wider pattern and allow you to see both sides of the road. Comes in handy for seeing critters in the bushes. I also rewired mine so I can also use them as daytime running lights without the headlights.
! didn't answer the original question.
It's easy to add a relay that gets its activation leg power from the original fog lights when on. the ground side of that can be wired into a hidden switch under dash.
This way the extra fogs will only activate when the original fogs are on and the microswitch has been triggered to ground.
The power for the lights themselves can come from an under-utilized fuse in the fuse box or direct from battery. If direct add an in-line fuse to this circuit.
The relay activation power can come from anywhere. The fog light circuit, another fuse that's hot with ignition on or direct from battery.
The fog light circuit means ONLY when orig fogs are on.
The hot in ign fuse is whenever the car is on. They can be used as daytime running lights like this.
Direct to battery is all times on and only turned off when the micro switch is open.
This will often lead to a dead battery if you forget to turn them off. I would not wire it this way, but it will work fine.
The rear defroster circuit might be an excellent choice. I'd have to looks at how that circuit runs in car. This circuit should have pretty good amperage delivery as it ran a heater.
If you use LED fogs the power requirement goes WAY down and wire size is less
important.
The relay will need .2 amps or less to trigger. Running the relay trigger power off of the original fog light feed will not affect the output of the lights.
Hope this helps.
Rick
It's easy to add a relay that gets its activation leg power from the original fog lights when on. the ground side of that can be wired into a hidden switch under dash.
This way the extra fogs will only activate when the original fogs are on and the microswitch has been triggered to ground.
The power for the lights themselves can come from an under-utilized fuse in the fuse box or direct from battery. If direct add an in-line fuse to this circuit.
The relay activation power can come from anywhere. The fog light circuit, another fuse that's hot with ignition on or direct from battery.
The fog light circuit means ONLY when orig fogs are on.
The hot in ign fuse is whenever the car is on. They can be used as daytime running lights like this.
Direct to battery is all times on and only turned off when the micro switch is open.
This will often lead to a dead battery if you forget to turn them off. I would not wire it this way, but it will work fine.
The rear defroster circuit might be an excellent choice. I'd have to looks at how that circuit runs in car. This circuit should have pretty good amperage delivery as it ran a heater.
If you use LED fogs the power requirement goes WAY down and wire size is less
important.
The relay will need .2 amps or less to trigger. Running the relay trigger power off of the original fog light feed will not affect the output of the lights.
Hope this helps.
Rick
QUOTE(technicalninja @ Aug 2 2023, 12:46 PM) 
! didn't answer the original question.
It's easy to add a relay that gets its activation leg power from the original fog lights when on. the ground side of that can be wired into a hidden switch under dash.
This way the extra fogs will only activate when the original fogs are on and the microswitch has been triggered to ground.
The power for the lights themselves can come from an under-utilized fuse in the fuse box or direct from battery. If direct add an in-line fuse to this circuit.
The relay activation power can come from anywhere. The fog light circuit, another fuse that's hot with ignition on or direct from battery.
The fog light circuit means ONLY when orig fogs are on.
The hot in ign fuse is whenever the car is on. They can be used as daytime running lights like this.
Direct to battery is all times on and only turned off when the micro switch is open.
This will often lead to a dead battery if you forget to turn them off. I would not wire it this way, but it will work fine.
The rear defroster circuit might be an excellent choice. I'd have to looks at how that circuit runs in car. This circuit should have pretty good amperage delivery as it ran a heater.
If you use LED fogs the power requirement goes WAY down and wire size is less
important.
The relay will need .2 amps or less to trigger. Running the relay trigger power off of the original fog light feed will not affect the output of the lights.
Hope this helps.
Rick
Yes, very helpful Rick - thanks. I'm sure I won't be running straight off the battery which is why I'd like to use the stock switch and relay from the later '74 harness that I have. I need to learn how to connect them to what's already in the '72 harness/fuse box tho. I know you sort of explained it, but you obviously know the electrical angles better than me. For instance would I be cutting the red/white switched power wire from the stock fog circuit and tapping into, twisting on a power wire to the ('74 relay) aux. lights relay? ..or just power the new added relay thru it's own fuse via an open spot on the fuse block? - Oh, I have extra fuse panels too and have been contemplating cutting one of them in half and mounting somewhere under the dash to add extras to (in the case of this car - aux. fogs, intermittent wipers, electric washer pump, maybe: voltmeter, electric antenna, etc).
Also, I don't think that the '74 came with rear window defrost, but I will look at that harness again.
.
I have some experience in this area:
Click to view attachment
I replaced the fog lights with Cibie Tango driving lights, but modified the wiring to the relay so they are only available on high beam; the outers (Cibie Iode 45 fogs) were done by adding an extra relay switched (and fused) circuit that allows them to only run when headlights are dipped beam. In this way you get a choice of lighting setups but never overload the alternator.
I made up my own loom and wiring (for the added lights) to run alongside the existing harness, much as you are planning to do by modifying an extra factory harness. Feel free to PM me if you are struggling with wiring / relays / fusing.
- Tony
Click to view attachment
I replaced the fog lights with Cibie Tango driving lights, but modified the wiring to the relay so they are only available on high beam; the outers (Cibie Iode 45 fogs) were done by adding an extra relay switched (and fused) circuit that allows them to only run when headlights are dipped beam. In this way you get a choice of lighting setups but never overload the alternator.
I made up my own loom and wiring (for the added lights) to run alongside the existing harness, much as you are planning to do by modifying an extra factory harness. Feel free to PM me if you are struggling with wiring / relays / fusing.
- Tony
LEDs in all the front facing lights. Fogs, Frogs, headlights
If you are going fast, you need a lot of light. I think that you can never have too much. In a turn you want to see where you are going
Bob B this is in #41
Click to view attachment
If you are going fast, you need a lot of light. I think that you can never have too much. In a turn you want to see where you are going
Bob B this is in #41
Click to view attachment
QUOTE(Retroracer @ Aug 2 2023, 08:26 PM)
I have some experience in this area:
Click to view attachment
I replaced the fog lights with Cibie Tango driving lights, but modified the wiring to the relay so they are only available on high beam; the outers (Cibie Iode 45 fogs) were done by adding an extra relay switched (and fused) circuit that allows them to only run when headlights are dipped beam. In this way you get a choice of lighting setups but never overload the alternator.
I made up my own loom and wiring (for the added lights) to run alongside the existing harness, much as you are planning to do by modifying an extra factory harness. Feel free to PM me if you are struggling with wiring / relays / fusing.
- Tony
Hey Tony, that’s a great shot of your car and lights! ..thanks for your comments and insight.. I like the way you’ve separated out the external lights to only work with low beams or high depending, and the options that it affords. I have the JWest wiring “thingy” that lets you run the original fogs with no headlights turned on (still have to figure out how to attach that too), so maybe I’ll use that for the low beam side w/ original fogs or the pilots I have - then hook up the bigger aux.fogs to only work w/ high beams.
I wonder - is there a way to put a rear fog on the same circuit as the aux. front fogs? Is that just a matter of splicing the rear wire into the relay for the aux. fogs and running a bigger fuse at the block? Or would a rear have to be on its own circuit?
A few years back I was on a road trip driving thru the night and got into heavy fog in deepest Mississippi/Alabama and wanted/needed more light (in a modern Volvo w/fogs running), so that’s the main reason I’m doing these - plus the rally look
Yeah make sure you are doing LED conversions for all the forward facing lights. Incandescent and halogen lights draw a lot of power from our already anemic alternators.
Zach
Zach
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.