3 function fog lights
Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=134365
Printed Date: July 04, 2025 at 6:09 PM
Topic: 3 function fog lights
Posted By: mindlesspleasur
Subject: 3 function fog lights
Date Posted: June 13, 2013 at 5:05 AM
Hey folks I wonder if you could help me out, I purchased a set of fogs for my 94 Del Sol that have 3 functions. There is the regular fogs, which I want to use as normal, (on/off using the factory switch) this part is working no prob. Second function is a LED halo which I want to switch separately using its own switch. Third function is a strobe, these I want to connect to my turn signals so each strobe works with its corresponding turn signal. I believe this requires the use of relays, but I'm not sure of how many or how to wire them. Any help would be greatly appreciated thanks.
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Rob
Replies:
Posted By: oldspark
Date Posted: June 13, 2013 at 7:22 PM
It's probably just a matter of connecting each side to its corresponding flasher signal (+12V) but using diodes in each line to prevent fog feeding the flashers, and diodes between the fogs and the switches (so the flashers don't feed the other side or the switches).
So probably 4 at least diodes with line ends towards the fogs.
If the fogs are under 1A each, then 1N400x diodes (eg, 1N4004).
If <3A, 1N540x (eg 1N5404).
[ Any diode in those series will do but I've given the common 400V versions which are often used for (relay) spike protection etc. ]
If the fogs take a higher current, or if the ~0.7V diode voltage drop is too high, then a relay is required for each fog. It's the same wiring but with the 1N400x diodes to the respective relay's coil 86 (85 to GND, 30 from fused +12V & 87 to the fog +12V), BUT that may not be suitable for the strobe...
If the strobe is a fast strobe (as used for LEDs), then the relay is unsuitable - it may not switch fast enough or may fail quicker.
But an alternative strobe circuit should be possible.
If you get relays, I suggest SPDT (5 pin relays with 87 & 87a outputs) which is our general recommendation anyhow (same price, same footprint/terminal locations, and one part fits all) but it MIGHT be one of the requirements for the strobe circuit.
Likewise buy several 1N4004 (else 1N4007) diodes - maybe a pack of 10 or even 100 if the per-diode price is low - as they are so often used in a multitude of car circuits - eg, joining sources/signal as in this case, isolating alarms from other circuits using door switches, etc.
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