The fog lights are all in and wired, and I had only problem left to go; I wired in the fog light switch and light from separate fused 12v sources. This meant the switch worked, but the light was ignition=on.

That's not right,

so I re-wired the light in series with the 12v in to the switch. The fog light switch is running off fuse 14, so I only have fog lights when headlights are on, as OEM rear fog light. However, the switch light was headlight on = foglight switch on.

That's not not right either. So I'm thinking the power source for the light in the switch should be wired in series with the switch out to relay, so it's only powered when the switch is foglights = on. Right?

Sheesh. Is the last version the correct wiring procedure for the front fog light switch?

Thanks O Brickboarders,

Lanval

That fog light switch you are using. Is it the same one the 1986+ 240s have that is mounted horizontally just below the headlight switch?

That one has a light inside, which is on when the switch is closed and the headlights are on. Power comes into the switch, then closing the switch sends power to a terminal for the fog lights, and inside the switch body to the light. The terminal on the light is its ground connection.

If you are using a different fog light switch, maybe one mounted in the central control panel, check for the same internal connections. Close the switch, apply +12V to the switch input and ground the light terminal, light should come on if the bulb is good.

Without knowing more about your car model and year, that's my best guess.

Good Luck,

Bob

:>)

Bob,

Sorry, clarification:

Car = 92 244 GL auto
Foglight = auxiliary front foglight switch/green in center console.

The back of the switch has 4 spades
1 = 12v in to switch
1 = 12v out to relay, switched power
1 = 12v fused to light
1 = 12v ground to body for light

I assumed that the switch had an internal regulator which only allowed the light to come on when switch is in 'on' position. Either this is not the case, or the switch is broken internally.

I say this because if you have constant 12v power to bulb, it's always on. flipping the switch itself has no effect. Thus it seems to me the only way to get 12v to the bulb in on position only is to have the power to the bulb running of the 12v out to relay...

Currently the bulb 12v power is coming from the 12v in to switch, which as I said, is run off the same fuse as the rear foglight switch on the dash, above the headlight knob. This means, though, that when the headlights are in 'on' position, the foglight bulb lights up, regardless of whether the foglight switch is in 'on' or 'off' position.

So, I'm thinking that I need to wire the bulb off the 12v out to relay, since that line only has power when the switch is the 'on' position. I'll check out the OEM switch today, and see how they did it. Thanks for reminding me of that.

Best,

Lanval
--
92 240GL - Virgos, IPD 25/25 sways, 150,000 mi strong

So, I'm thinking that I need to wire the bulb off the 12v out to relay, since that line only has power when the switch is the 'on' position. I'll check out the OEM switch today, and see how they did it.

Don't take the time to check the OEM, you are on the right path.

Just jump the 12v input to the light onto the switched 12v output from the switch.

Just remember that the signal light can be on and the fog lights not. I check my rear fog lights (got two on each 240, '86 and '88) by backing up towards a closed store window and watching the reflection.

Good Luck,

Bob

:>)