I have a 2020 Sentra that I was putting in an aftermarket fog light kit for my son. I was surprised to see factory wiring in there for the fog lights but thought it would be much easier to use it than run the new harness. The only issue I have is that I'm trying to identify the fog light output wire from the BCM and I'm struggling. The diagrams I can find all say "Combination Switch output 4 or 5 or whatever" but don't say the actual function of that output. Can anyone point me to a resource for the combo switch functions/wire function or just flat out tell me the color/pin out of the fog light wire from the BCM? Thanks!

The combination switch uses a strobed matrix and not discrete wires for each function. In a typical late model Nissan matrix there are 5 outputs and 5 inputs, the inputs have a pull-down resistor to ground and the outputs are P-transistors to drive the line high. The BCM "strobes" the outputs one after another for 1 millsecond each. For any switch which is "closed", the voltage shows up on the corresponding input. If the switch is "open", the input stays low. There's a matrix diagram in the ESM showing which in and which out will turn on the fogs, but there are diodes inside the switch and you'll need to add an external diode for it to work right. If you want to post or PM me your VIN, I can look up the exact wire colors for your son's ride next time I'm at the shop.

PS - The BCM reads the switches but it doesn't actually run the fog lights. The IPDM does that, under CAN command from the BCM.

Is there a fog relay in the IPDM that I can ground a leg and turn on the lights? I'm just trying to find someplace I can pop a + or ground signal that will turn on the lights with the factory wires. Otherwise, I'll just use the aftermarket harness that came with the lights. I don't want to fry a multiplex switch, I like simple electronics

No, the relay is internal to the IPDM. There isn't really anything to fry in the combination switch, though. The circuit uses all high-value pullups, so the worst a crossed wire causes is something turning on and off. You'll just need a switch plus any common diode like a 1N4001 or 1N914 to wire in series. Like I said, I can give you explicit wire colors and instructions if you want them.

As most that know me will attest: "I'll try anything once" I have several 1N4001 diodes and a few hundred different resistors if I need them. Let me know if you need the VIN or whatever and I'll get it over to you. Thanks for your help, I hope this will be valuable for others too, as I haven't seen a lot of factory integration tips for the latest Sentras.

imtfox wrote: ↑

Sun May 02, 2021 10:07 pm

As most that know me will attest: "I'll try anything once" I have several 1N4001 diodes and a few hundred different resistors if I need them. Let me know if you need the VIN or whatever and I'll get it over to you. Thanks for your help, I hope this will be valuable for others too, as I haven't seen a lot of factory integration tips for the latest Sentras.

Happy to help. I'll just need your VIN to make sure I pull up the right documentation. You can PM it if you don't want to post it. I'm actually thinking to do a short "How To" about adding switches to the matrix, since there seems to be a lot of mystery about the subject and they really aren't mysterious. Nissan's documentation about it is really quite good. The ESM's all have a section showing the exact matrix and whether it's arranged P or N, so all you need to do is plot In X by Out Y for the switch you want to use, then get the wire colors from the WD and wire across them with a diode facing in the correct direction. Definitely not rocket science!

Okay, I just posted a generic How-To about fooling Combo Switches here:

topic629036.html

I know the WD's for '20~'21's aren't available, so just get me your VIN and I'll pull up the info for your son's ride from ASIST.

Since I'm not able to PM you, the vin is 3N1AB8CV6LY239XXX. That other write up is stellar BTW.

imtfox wrote: ↑

Mon May 03, 2021 6:50 pm

Since I'm not able to PM you, the vin is 3N1AB8CV6LY239XXX. That other write up is stellar BTW.

Glad you liked it! I'll get your info at the shop tomorrow and post it when I can, probably in the evening.

Got a chance first thing, here you go:

In 1 is VIO on pin 1 of M28, Out 5 is YEL on pin 2. Cathode stripe needs to face YEL.

OK, that all worked for the fog lights. I got the 1 and 2 pins jumped by the switch with the diode and it turns the fogs on and off and even pops the light on the dash to show the fogs are on. So many thanks!
the connector at the combo switch fog lights on New issue he says that the reverse camera is showing a blue screen sometimes... but I'm going to let them fix that under warranty. No way what I touched today could have broken that... :P

Nope, the cam wiring goes straight to the AV and noplace near the steering column. "Blue screening" usually means an issue with the cam itself, they generally go black if it's a wiring problem. Looking good with those fogs, you're most welcome!

OP, which trim do you have? Curios if all trims are pre wired.
Did you had just plastic plug in place of a fog light?

Hey there. I just bought a 2022 Sentra SV and would like to install fog lights as well.

Based on this awesome thread, I think I generally understand what the process did to get it to work. A few questions (forgive my noob-ness)

1) What fog light kit did you buy? I’ve seen a few and just curious what you installed.
2) The splice wiring as instructed would take place inside/under the steering column? Any pointers as to how to access the wiring in there?
3) Are there wiring pigtails inside the bumper where the fog lights are installed? Any pointers on how to get into the bumper?
4) Stupid question - so in a factory vehicle with fog lights inside…the BCM is different than in my vehicle? Hence the reason to splice the wires and spoof the BCM with a diode?

Thanks!

1) I'll let the OP respond to that
2) There are either 2 or 3 phillips screws holding the clamshell cover to the steering column, 2 in front that can be seen when the wheel is turned and maybe one on the bottom, I can't recall. Then the clamshell just pries apart. The connectors for the spiral cable and switches are completely exposed with the clamshell removed.
3) Usually, yes. They'll be taped back to the harness.
4) No, the turn/headlight stalk is what differs. The BCM is the same but there's no Fog Switch on the stalk.

Wow thanks for the quick response! Sorry for all the questions. Just don't want to blow up a new car!

1) I'm holding my breath! Come on OP don't fail me now!
2) Perfect, doesn't sound too bad.
3) I installed the Nissan OEM fog light kit on a 2012 Frontier. It was similar, the pigtails were right there and just replaced the covers with the lights.
4) Hmmm... so my OEM Frontier fog light kit came with a new stalk that had the fog light switch and it worked perfectly - no extra diode needed. In these Sentra fog light kits, they come with a pushbutton fog light switch that goes into a small slot to the left of the steering wheel. Where I'm confused is, do you know why the upgraded OEM Frontier stalk with fog light control I installed moons ago didn't need an inline diode? Was there one built into the Frontier OEM stalk switch? If that's the case, I'm now wondering if the nissan oem fog light switch for a Sentra SR (which comes with fog lights) might avoid needing the inline diode?

Sorry about all the questions. Just trying to wrap my head around it.

Just wait until I start asking how to hook up/activate front parking sensors...hahahaha!

Also, I'm assuming the wiring direction you sent on the 2020 Sentra SV should still apply on the 2022 Sentra SV?

Thank you!!!

Wait, my bad. Upon looking at the parts list, it looks like the fog lights are factory controlled by the stalk on the Sentra as well. The aftermarket kits use a little push button switch that gets mounted in the dash to the left of the steering wheel.

So, last question (I think) would be- if you upgraded the Sentra SV stalk to a Sentra SR stalk with fog light control, and plugged in the fog lamps to the pigtails behind the SV bumper, I imagine you'd have close to "factory" fog lights?

NissanDriverMD wrote: ↑

Thu Feb 17, 2022 6:27 am

Wow thanks for the quick response! Sorry for all the questions. Just don't want to blow up a new car!

You're most welcome, and don't apologize. My Dad used to say, "The only stupid question is the one you don't ask and get your a$$ kicked because you didn't." He was right.

NissanDriverMD wrote: ↑

Thu Feb 17, 2022 6:27 am

In these Sentra fog light kits, they come with a pushbutton fog light switch that goes into a small slot to the left of the steering wheel. Where I'm confused is, do you know why the upgraded OEM Frontier stalk with fog light control I installed moons ago didn't need an inline diode? Was there one built into the Frontier OEM stalk switch? If that's the case, I'm now wondering if the nissan oem fog light switch for a Sentra SR (which comes with fog lights) might avoid needing the inline diode?

Most of the models till '19 had "saddle" type combination switches that could be replaced without removing the steering wheel and spiral cable, so the kits simply included a new combo switch with a Fog position. The majority of the new stuff is coming through with "full circle" type switches that need a lot of expert disassembly/reassembly. Hence, no factory kits. So you need a separate switch and a diode to utilize the factory mechanisms.

NissanDriverMD wrote: ↑

Thu Feb 17, 2022 6:27 am

Also, I'm assuming the wiring direction you sent on the 2020 Sentra SV should still apply on the 2022 Sentra SV?

The WD's indicate the Fog system on the '20 and '22 are identical.

Ha! Your Dad was right!

It's a shame they didn't just stick with the easy combo switch-a-roo for minor upgrades like this!

Thanks for comparing the WD for the 2022 as well!

Who knows, maybe I'll get adventurous and put a kit in now that I have a much better understanding thanks to you!

You're most welcome, happy motoring!