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Here is a link >> https://www.bernardiparts.com/Images/Install/2017_Ridgeline_FogLights_AII02857-34.PDF

Resources such as this are abundant on the web. A quick search for Ridgeline Fog lights or Ridgeline OEM Fog lights, would land you in one of many sites that carry OEM wiring diagrams.

Also the 2017+ do not carry the wiring diagrams like the G1.

 

Yes, but I can't share it.

$10 buys you access to every Honda service manual and TSB dating back to 1990 for 24 hours.

http://techinfo.honda.com

The fog lights are powered by a yellow wire connected to pin 9 of the under-hood fuse/relay box through the M6 fog light relay. The coil of this relay is energized by the MICU grounding a light green wire connected to pin 73 of the under-hood fuse/relay box. The MICU determines when to ground the relay coil based on signals from the combination light switch, automatic lighting control unit, automatic high beam control unit (camera), and gauge control module.

You'd need to energize the coil of the fog light relay using a normally-open relay contact driven by the parking lights in series with a normally-closed relay contact driven by the high beams. The challenge will be that there doesn't appear to be a +12V signal to the parking lights. Instead, the LED DRL/parking lights receive a control signal from the MICU.

 

Thank you, both for the replies.
I'll take a look at the schematic you mentioned, smufguy.
zroger73, thanks for the writeup. Having been an old school electronics tech for nigh onto 50 years and a certified shade tree mechanic I believe my plan will be doable.

Again thanks to you both.
Joe

 

The high-beam signal is easy - it's just switched battery voltage. The "parking light" signal may be the challenge. The LED "strip" in the BE's headlights serves as both DRL's and parking lights. The MICU tells the headlight assembly to operate these LED's at one of two brightness levels depending on a combination of inputs. The LED's operate at high intensity as DRL's and parking lights, but switch to low intensity when the low beams are on. The intensity of these LED's is controlled using PWM. Honda does not specify if the signal between the MICU and headlights that accomplishes this is encoded information over a data bus or a simple trigger like +5 or +12 VDC. This would be a great time to grab your DSO.

If you could get a signal for "DRL low" and combine it with the high beam signal, you could turn the fog lights on when the low beams are on and the high beams are off, but the vehicle already does that. As far as operating the fog lights with the parking lights only, when the parking lights are switched on you'd lose the "DRL low" signal (and fog lights).

Ideally, you'd need to design a controller that would read the vehicle's data bus with the following logic:

IF headlights OR parking lights are ON AND high beams are OFF THEN turn the fog lights ON.

 

@jmbiii If you actually accomplish what you’ve described the documentation you create and photos you provide will be referred to by many others, just food for thought.

 

did anyone do it?

 

Not yet, but I'm going to.
Of the two smaller pins (and females in the socket) for the fog light relay, the one on the passenger side gets grounded to turn the fog lights on. The other small pin, driver's side, has a constant +12. That ground gets disconnected when the high beams get turned on. My plan is to put a small piece of "bell" wire into the left side, small pin socket and plug the relay back in. (If that doesn't stay fixed in place well enough, I may solder it to the pin on the relay, up near the relay body itself. The relay then will not seat "fully" into the socket, but well enough to make good contact) Then just run that wire to a switch. The other side of the switch is ran to a ground. The OEM switch will still activate the fogs as normal, they will go off with the high beams or just parking lights. Flip your new switch and they will come on, whenever you want them to. Caution- they will be on at anytime, even with the vehicle off. Ultimately, my plan is to use a wireless 12v relay/fob to supply the ground and to be my "switch." It will get its 12v power from a switched ignition source, therefore go off when the vehicle is off too. It will also be less obtrusive and no holes in the dash or firewall. If you'd rather, you could just run a diode from the ground of the fog light relay to the ground of the low beam relay (in the socket right next to it) but that will make your fogs on anytime the headlights are on, high or low (I'm not sure why that relay still has a ground even when you switch to high beams).

 

Did you ever do this? I want to use the fogs anytime as a DRL on my RTL. Did the mod on my Tacoma where a tab was just bent on the relay and pulled ignition switched power from another source. That way the fogs would be turned on by the factory switch in the vehicle when the ignition was powered on and would stay on, even with the hi beams. Anyone figure this one out yet?

 

Thread necro for possible updates.

 

No, not yet. I'm waiting until my warranty is up in a few months. Every time I try something, I get a Christmas tree on my dash, then I have to reset codes.