Running Fog Independent of Headlight (1 Viewer)

[TeCKis300]

This is a riddle that's brought up from time to time - How to enable running the fog light without the headlight being on, with the factory fog light switch.

Factory logic, allows fogs to function only when the headlight is on. I'd like to turn them on independently at times. I've made this mod previously with an IS300 by jumpering some wires, but haven't had time to sort a solution on the 200-series yet.

Leveraging the hive mind here to give this deeper thought.

Seeding this with the following. If I'm reading this correctly...

Assumptions:
1) Fog light switch on the steering column pulls FFOG (plug E2, pin 28) on the main body ECU down to ground as the turn on signal.
2) FFGO (plug E1, pin 4) on main body ECU pulls FR FOG Relay (pin 1) down to ground to turn on the relay and power the fog light on

I believe the fog on logic with headlight only is within the Main Body ECU

CAUTION!!! HIVE MIND, PLEASE ASSESS WHAT I'M SUGGESTING BEFORE ANYONE PHYSICALLY PERFORMS THIS MOD AND BREAKS SOMETHING.
Mod:
EDIT - Recommended solution here
3) Jumpering the circled pins may bypass the fog with headlight on logic in the main body ECU? Allowing the fog light switch on the stalk to directly pull down FR FOG Relay to ground, and turning on the fog?

*Ignore gray block on rear fogs as that's for international spec 200-series.

 

[KLF]

I think it is important to be able to also manually turn the fogs OFF from the switch (I assume you want to do this), and I am pretty sure it's a DOT requirement that fogs turn off when Hi beams are on (someone please correct me if they know for sure I am wrong). I would need this functionality, in order to be able to pass annual inspection, and I get a fussy inspector.

I have done this exact setup in my Miata, it is very common and easy to have the fogs come on with the ignition (one jumper wire in the fusebox under the hood), while the stalk switch can still turn them off. I had to add a small relay to make sure they turned off with Hi beams. Now I have very bright LED bulbs installed, all in the effort to make the car less invisible on the road.

Carry on... and safe travels.

 

[ton504]

What if all you need is full time 12v at FRFOG Relay pin 2 vs 12v at FRFOG Relay pin 2 whenever the headlight (really, the tail light) is on?

 

[619TOY]

This is exactly what I’ve proposed in the past as well. One step I would recommend would be to measure the current out of the switch to see if the switch itself is passing the current as opposed to a transistor inside the BCM. If the switch is actually passing the current I'd feel pretty comfortable with the mod. If not, I'd recommend adding a relay to pass the current (same current on both red wires). I realize that post BCM the wire is just triggering a factory relay also, but it's still something I'd check.

 

[TeCKis300]

Good stuff @619TOY. I'm liking the idea of bridging outside rather than jumpering.

Anyone wants to put a meter on these wires under the instrument panel?

 

[luke27617]

Why not use wiring kit for any off road lights and connect fogs to those instead of regular relay and bring cables into cabin with an independent switch. Exactly how you would wire any off road lights. Quick, easy and not messing with factory wiring in case you want to reverse. You can as well keep everything factory but tap in fog lights wires to this independent switch which becomes an overwrite to keep it on all the time.

 

[grinchy]

step 1, tap the control on from the stock fog light switch
step 2, tap the hi beam on at the stock headlight switch
relay waterfall
relay one is normally closed, and is open based on hi beam on
relay two is normally open and is closed when fog light is on
output of relay two joins in to fog light control before fog on relay

state 1
headlights off fog off - no
state 2
headlights off fog on - yes
state 3
headlights on fog off - no
state 4
headlights on fog on - yes
state 5
headlight hi off fog off - no
state 6
headlight hi On fog on - no

 

[grinchy]

There is probably a foxy way to use normally open and normally closed from headlight hi and from fog switch using just one relay but I’m not sure if the relay will close or not if both signals are present.

 

[mtweller]

Good stuff @619TOY. I'm liking the idea of bridging outside rather than jumpering.

Anyone wants to put a meter on these wires under the instrument panel?
View attachment 2333902

What's the source for these diagrams? Sorry, nothing to add to the foglight discussion.

 

[bloc]

What's the source for these diagrams? Sorry, nothing to add to the foglight discussion.

Factory service manual.

 

[bloc]

Why not use wiring kit for any off road lights and connect fogs to those instead of regular relay and bring cables into cabin with an independent switch. Exactly how you would wire any off road lights. Quick, easy and not messing with factory wiring in case you want to reverse. You can as well keep everything factory but tap in fog lights wires to this independent switch which becomes an overwrite to keep it on all the time.

Because we want to use the perfectly good fog light switch that is already on the stalk, and the factory wiring is almost certainly higher quality and more durable than aftermarket stuff.
Personally I prefer to use what’s there instead of add extra switches and wiring all over the place. Even if we need to revert to factory setup it is only a couple high quality crimps or solder joints.

 

[grinchy]

step 1, tap the control on from the stock fog light switch
step 2, tap the hi beam on at the stock headlight switch
relay waterfall
relay one is normally closed, and is open based on hi beam on
relay two is normally open and is closed when fog light is on
output of relay two joins in to fog light control before fog on relay

state 1
headlights off fog off - no
state 2
headlights off fog on - yes
state 3
headlights on fog off - no
state 4
headlights on fog on - yes
state 5
headlight hi off fog off - no
state 6
headlight hi On fog on - no

I think I’ve convinced myself that this is too complex.
tap the fog switch. Run it thru as switched line not control on relay that is normally closed with output to the fog light relay stock Input. Tap headlight Hi on and put it to normally Closed control. When the headlight Hi is on, it will Open the relay and fog light is disabled. Otherwise the circuit I controlled by the fog switch on/off. Regardless of normal healight switch.

 

[electro992]

I posted this in the past but never got around to trying it. If someone wants to try it out it can be done without cutting or modifying any factory wires. The modification is done to the fog light relay itself which can be easily replaced. You want to take pin 2 of relay 10 (FR FOG) in the engine bay and bend it out as shown in the attached picture. Use a spade terminal to connect that pin to switched 12V.

Fog lamp mod - Anyone figured out a low/high/independent option?

With the 100 Series a single wire in the master light switch can be modified to allow use of the fog lamps in expanded scenarios, i.e. run them in park, low beam or high beam. Has anyone figured out such a thing with the 200?

forum.ih8mud.com

http://www.top4runners.com/cgi-bin/image.pl?/ja/2007/115vpower/115vpower4.jpg

 

[ton504]

@electro992

Just what I was thinking. Glad to see it works for the 4 runner folks. I'm not sure if I would do this mod as I never felt the need to run fog only.

 

[TeCKis300]

Good stuff! We've got several strategies here. Just need to put a probe on the thing.

The manuals website seems to be down at the moment. Where is this taillight relay located?

 

[ton504]

Good stuff! We've got several strategies here. Just need to put a probe on the thing.

The manuals website seems to be down at the moment. Where is this taillight relay located?

You probably want to be looking for the FR FOG relay. Its likely in the engine bay fuse box.

 

[TeCKis300]

Anyone have time to meter leg 2 of the FR FOG Relay to see if it's switched 12V with the tail light? Should be relatively easy to access in the engine bay.

 

[TeCKis300]

So I went and probed the FR FOG relay at lunch. Easy thing to get to.

May be two things we need to solve to get the fogs to work completely independently.

1) FR FOG Pin 2 is not powered until the rear tail lights come on.
2) FR FOG Pin 1 is not grounded until the headlights come on. (therefore fogs don't just turn on with parking lights (i.e. tail lights)

It may be good enough to solve #2 to allow the fogs to come on with parking lights rather than being strictly tied to headlights. That's primary when I use fogs independently in my other cars. Dusk or dawn, or low visibility situation, to have my fogs on with parking lights.

 

[electro992]

If that's the case I would err on the side of caution and suggest using an external switch. Ground Pin 1 of FR FOG and use an external switch between the battery (or ignition switched 12V) and Pin 2 of FR FOG, much the same as installing any other accessories.

I would not recommend cutting FFOG as described earlier in this thread because we don't want the factory switch to pass more current than it may be rated for.

 

[TeCKis300]

^All good points. I'm considering various strategies. It really comes down to the use cases I want to use the fog light for.

I agree with your concern about not cutting the relay to FFGO. E1 Pin 1 is a heavier gauge wire than E2 Pin 28, and that's a clue that the switch is not expected to carry the same current. It may very well work as the current coming through the FOG relay is minimal. Perhaps that current going to the BCM also drives the indicator lamp on the dash.

At the risk of complicating this discussion - for me, it's also consideration of the lighting system as a whole because I intend to take this further. Actuating high beams will turn off fogs. Undesirable for me as it effectively cuts flood for spot. (to satisfy DOT laws of max 2 pairs of driving lights which I don't particularly care about). I also will be modifying my high beams which in my '09, are DRLs. I may want my fogs to also perform as driving lights.

I may very well just add a relay and switch outside of this so I can turn on/off the fogs and avoid additional complexity here.