Built-in Fog Light Switch (Front/Rear) Installed

[Aminorjourney]

So I took the plunge and picked up a switch for factory-style front/rear fogs. My ultimate goal is to implement front-fogs in the lower grille as some others have done, but have it tied to the light switch.

So far, it's just the switch install, and some FORsacn tweaks, giving me front fog IPC telltale and auto-cancel for front fogs for when I actually install them. I will need to wire up a custom loom between front fogs and BCM -the factory manual seems to suggest it should work if I run the appropriate wires. (and relays)

The rear fog light switch and tell-tale have been enabled in FORscan, but they're not toggling on the IPC like the Front fog. Interestingly, I had a play yesterday evening with FORscan and was able to track the switch registering as a rear fog switch push (momentary only, so it showed ON when pushed and off when released).

I was also able to send the IPC the correct CAN code via FORscan to turn the tell tale on and then off again, so if for some reason my plan of trying to get it working factory-style doesn't work, I can program something on the can bus to latch the rear fog and activate the tell tale, using an aftermarket relay if required.

It's late, and I'm tired, and it's been a week - but hey, have a video. Turns out the light control cluster is modular, and we can switch out our bed lighting switch to keep a factory look.

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[Truaz]

That’s cool!

 

[nate002]

Interesting, can’t wait for the next one!

 

[21st Century Truck]

So I took the plunge and picked up a switch for factory-style front/rear fogs. My ultimate goal is to implement front-fogs in the lower grille as some others have done, but have it tied to the light switch.

So far, it's just the switch install, and some FORsacn tweaks, giving me front fog IPC telltale and auto-cancel for front fogs for when I actually install them. I will need to wire up a custom loom between front fogs and BCM -the factory manual seems to suggest it should work if I run the appropriate wires. (and relays)

The rear fog light switch and tell-tale have been enabled in FORscan, but they're not toggling on the IPC like the Front fog. Interestingly, I had a play yesterday evening with FORscan and was able to track the switch registering as a rear fog switch push (momentary only, so it showed ON when pushed and off when released).

I was also able to send the IPC the correct CAN code via FORscan to turn the tell tale on and then off again, so if for some reason my plan of trying to get it working factory-style doesn't work, I can program something on the can bus to latch the rear fog and activate the tell tale, using an aftermarket relay if required.

It's late, and I'm tired, and it's been a week - but hey, have a video. Turns out the light control cluster is modular, and we can switch out our bed lighting switch to keep a factory look.

OP, thank You for this ongoing research. Having had a US-spec BMW, a Ford Fusion and a Ford Mach E with factory-installed or self-installed OEM rear fog lights, I thoroughly appreciate having them when it counts.

NOTE for Your sleuthing: when I had installed a Ford OEM rear fog light onto my US-spec Mach E, I discovered that FORScan only listed one needed software change for this function within the BCM, whereas the BCM in the Mach E actually needed two separate software line changes. A German non-Mach E Forum member who specializes in Ford software found this additional solution by comparing the US/North America spec and EU spec BCM schematics for the Mach E.

Additionally, when I replaced the US-spec Mach E light control button with the Euro-spec Mach E light control button, I found out that there was no need to run a new wire from the light control button to the BCM.

Here's my write-up from the Mach E Forum blog. Maybe it'll be helpful to You:

https://www.macheforum.com/site/thr...nish-a-rear-ender-accident.28707/#post-845377

Separately, on my last trip to Europe I found out from Euro Ford dealer technicians that, as the F150 Lightning is not homologated for EU approval, the Lightning tail lights do not have an option for an internal OEM rear fog light, unlike the Mach E which does have this rear fog light built into its reverse center light (as described in the URL just above).

 

[roddiaz1]

Thanks for tackling this project. When complete, this will help many folks out there.

 

[Aminorjourney]

Thanks all - I'm wondering if there's lessons to learn from our Bronco cousins. They do have the option to add rear fogs, and I'm wondering if the lack of tell-tale on the IPC for the Rear Fog is part of a code issue, or just because I don't have anything plugged into the right BCM circuit for this.

Given that the Rear Fogs use a PWM controlled circuit, I wonder if it's just seeing an open circuit and therefore not showing it. I did some more digging into the FORscan thread on this one - and I think it's going to be a while...

 

[DavidS]

With the headlights placed so low on the front of the Lightning, do fog lights really improve visibility?

 

[Aminorjourney]

With the headlights placed so low on the front of the Lightning, do fog lights really improve visibility?

Yes. Fog lights are designed (the SAE ones at least) to give a consistent, low spread of light that isn't blinding, but give you a better view of the road.

Most SAE lights I've seen are yellow (although many stock ones are white) and that can also improve visibility in thick fog. My experience with the Ford F150 Lighting main headlights is that they don't always do great in fog, and can sometimes get confused by reflections.

As for the rears? Personal preference. I would rather allow my truck to be seen further down the road in heavy fog than the regular lights allow - and here in the PNW we do get some really nasty fog.

 

[rdr854]

We lived in Belgium years ago (actually decades) and rear fog lamps were mandatory. We had a US spec Volvo 244 and my Dad had to add the rear fog lamp so that it would pass the Belgian inspection. Interestingly, this was not required in Germany when we were there (car bought in Germany as part of US forces before moving to Belgium to months later).

 

[jwrezz]

Question for clarification, a "telltale" is a light on the switch indicating it's on or off?

 

[Aminorjourney]

Question for clarification, a "telltale" is a light on the switch indicating it's on or off?

Tell-tale on the dash - Ie, an icon that tells you it's on.

I think I've tracked down the issue - but I'll need a few minutes with the truck to confirm. Watch this space

 

[Firn]

With the headlights placed so low on the front of the Lightning, do fog lights really improve visibility?

In fog, yes.

In clear weather? No

 

[21st Century Truck]

Question for clarification, a "telltale" is a light on the switch indicating it's on or off?

On our Lightnings, the various telltales are the very bottom row of small colored icons on the IPC screen... i.e. high beams (blue), glare-free headlights (green), low 12V battery (red), etc. etc.

 

[Aminorjourney]

I did some more digging, and I am not 100% sure we can add the rear fog just from FORscan changes. What I need to do in order to be 100% sure is to order some pins to add the relevant pin connector on C2280C - which may only operate and latch if a load is detected on it. My current plan of action is to grab the right pins, then add a pin to C2280C (pin 25) and see if it's possible to drive a 12V load via what should be a FET driving that output pin. Since it's a FET, I'll have to make sure it's a small enough load to not cause issues.

In parallel, I'm going to capture the raw CAN/LIN bus traffic when the rear fog switch is pressed, which will tell us exactly what message the BCM is receiving. If the load test doesn't produce a latch, that CAN data will be the foundation for an ESP32-based middleware solution that can handle the latching logic independently of the BCM.

TLDR: Because the switch DOES register a rear fog switch press (but not a latch) that transmits on CAN/LIN and seems to arrive at the BCM, we can listen for that with a separate device - and then SEND the "illuminate the fog light dash icon/tell tale" to the IPC. We can also build some latching logic based on if the truck lights are on or not - which would be required to prevent the rear fogs coming on if we don't have the headlights on. That's a legal requirement in Europe that I'd like to mimic here.

However, that's the *worst case scenario*

Before I go further though, can someone confirm what I'm seeing here:

That the BCM pin I need for Pin 25 is... Molex 33012-3003?

I may actually have some in my stash

 

[I <3 My Lightning]

Above my pay grade but pretty cool reading about those that tinker with the electronics and build things... If I wanted a rear fog light, I would have used the trailer harness and added an additional running light of my choice as the rear fog light.

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