Having a ground-switched system works - I believe the horn is ground-switched - but can be more difficult to diagnose.
From your explanation of your switch wiring, though, it seems like you've wired the relay signal through the lightbulb. This means your foglights will go out if the bulb in the switch burns out.
The 56a vs 56b vs plain ground thing seems to depend on whether you want your foglights on only with the low beams, the high beams, or independent.
IMO, I would suggest the following changes:
- Rewire the relay as follows:
* Terminal 85 to the switch.
* Terminal 86 direct to ground or to the appropriate terminal on the headlight step relay.
* Optionally, an extra wire can be added from Terminal 87 to the fog-light switch, so a relay or fuse failure will cause the fog-light indicator to go out. This seems to be the stock configuration.
- Rewire the switch as follows:
* Pin 1 to key-fused power. You can use an existing fuse in the fusebox for this.
* Pin 2 to Terminal 85 on the the fog-light relay.
* Pin 3 to Pin 4 OR to Terminal 87 on the fog-light relay.
* Pin 4 to ground.
Please double-check my work since I'm just doing this in my head based on the diagrams available. This should accomplish the following things:
* Fog lights turn off when key is off.
* Switch circuit of the relay is not ground switched.
* Switch circuit of the relay is fused.
* Switch circuit of the relay is not dependent on a functional light-bulb.
* Optional: Fog-light switch bulb is off if relay has failed or fuse has blown.
* Optional: Fog-light control depends on the state of the headlights.
The suggestion is extremely interesting, thank you for it!
What if, though, instead of changing around a few terminals, we instead focus on Terminal 4 of the switch and terminal 86 of the relay.
So run Relay Terminal 86 straight to Fuse #1 which is hot only in run or start. Then run Terminal 4 to Fuse #8 which is hot at all times.
I'm also thinking off the top of my head, but this should accomplish the following:
* The fogs will now only work with the key on, which is good, that's a feature I like of the headlights that if I leave them technically on with the car off, it won't drain my battery.
* But the fogs will still be independent of low/high beam headlights
* Relay Terminal 86 is now getting a fused connection to the battery.
* Terminal 4, and therefore the light, are now independent of the relay, so if the light goes out the relay can still work as long as the switch is switched.
* Terminal 4 also has a fused connection and now the fog light switch light is out of the troubleshooting picture if the fog lights should for some reason fail to turn on.
In thinking more about it, not sure if that would totally work. But if we think about the whole system as a whole as configured today, if the fog lights don't work then it can only be three possible causes right?:
* Fog light bulbs bad
* Fog light switch bulb bad
* 30A integrated relay on terminal 30 has blown.
Those would be the only reasons right? So for the purpose of simplification, it's actually quite simple and is easy to troubleshoot if anything goes awry, correct?