Fog Light Modifications (2 Viewers)

[Ayune]

Wow. Amazing. Are you an EE or something? Also, I have a 2004... That looks like 98-2000?

Looks like on later trucks ('04-on) the relevant wiring is underneath the main engine bay junction box on connector 1A. I updated my earlier post to indicate wire numbers & colors to cut/jump.

 

[Ayune]

I think the point here is to run the fogs with the parking lights on, brights, etc. which in turn means the taillights are on as well. I don't think you would want to just run the fogs independently...

In that case you'd want to power the FOG relay's coil (connector 2J pin 11) from the TAIL circuit. On earlier trucks TAIL power can be found on connector 2F pin 2, or connector 2O pin 10 (both green wires), all at the left kick panel junction box.

Controlling the FOG circuit independently would be great for folks wanting to control a lightbar, with an aftermarket front bumper that lacks the OEM fog lights.

 

[DRoppolo]

Looks like on later trucks ('04-on) the relevant wiring is underneath the main engine bay junction box on connector 1A. I updated my earlier post to indicate wire numbers & colors to cut/jump.

I just figured this out myself. Been brainstorming a way to get these damn things to come on and stay on as long as the ignition is on. I want to replace the DRLs with them. I'm considering splicing into the DRL harness and running wires down to the fog light plug but I am concerned that the DRL system doesnt push enough voltage which makes them so dim. Otherwise this is frustrating AF and it shouldn't be.

 

[reznunt]

Ok, after further study you can jumper one accessible wire to make this happen on '98-'03 trucks:

On the driver's kick panel junction box:

- On connector 2J cut pin 11 (red-with-blue-stripe wire) leaving a pigtail to work with.

- Tape the wire end that's coming out of the harness (red-with-blue-stripe wire). This wire is hot when your headlights are on.

- Connect pin 11's pigtail to pin 8 on the same connector 2J (black-with-red-stripe wire). This is ignition-switched power.

This way the FOG relay's coil will get its power from the IGN circuit, ready to be activated when you turn on the Fog switch like always.

View attachment 2194277

For later year trucks this wiring is underneath the main engine bay junction box on connector 1A:

View attachment 2194842

- On connector 1A cut pin 61 (red-with-blue-stripe wire) leaving a pigtail to work with.

- Tape the wire end that's coming out of the harness (red-with-blue-stripe wire). This wire is hot when your headlights are on.

- Connect pin 61's pigtail to pin 60 on the same connector 1A (black-with-white-stripe wire). This is ignition-switched power.

Thanks for doing the legwork! Five minute mod with a t-tap works perfectly.

 

[MoneyMike]

Ok, after further study you can jumper one accessible wire to make this happen on '98-'03 trucks:

On the driver's kick panel junction box:

- On connector 2J cut pin 11 (red-with-blue-stripe wire) leaving a pigtail to work with.

- Tape the wire end that's coming out of the harness (red-with-blue-stripe wire). This wire is hot when your headlights are on.

- Connect pin 11's pigtail to pin 8 on the same connector 2J (black-with-red-stripe wire). This is ignition-switched power.

This way the FOG relay's coil will get its power from the IGN circuit, ready to be activated when you turn on the Fog switch like always.

View attachment 2194277

For later year trucks this wiring is underneath the main engine bay junction box on connector 1A:

View attachment 2194842

- On connector 1A cut pin 61 (red-with-blue-stripe wire) leaving a pigtail to work with.

- Tape the wire end that's coming out of the harness (red-with-blue-stripe wire). This wire is hot when your headlights are on.

- Connect pin 61's pigtail to pin 60 on the same connector 1A (black-with-white-stripe wire). This is ignition-switched power.

I was able to make it work on my 2003 LX470, but the location is under the main junction box under the hood , so it’s a considered a “later year truck” per your instructions. Thank you so much.

It’s the left connector on the headlight side held in by 10mm bolt.

 

[prickly]

Edit:

LX470 2007. I did the mod. An easy mod but was annoying for me to get to. Fogs work on ignition independent of headlights. But they still shut off on high beam.

 

[jasoncjung]

Thanks for doing the legwork! Five minute mod with a t-tap works perfectly.

@reznunt did you simply t-tap pin 11 to pin 8? or did you also snip both wires (11 and 8)?

I'd prefer to not snip wires if possible, but unsure this is realistic. Thanks.

 

[reznunt]

@reznunt did you simply t-tap pin 11 to pin 8? or did you also snip both wires (11 and 8)?

I'd prefer to not snip wires if possible, but unsure this is realistic. Thanks.

I followed Ayune's instructions explicitly and I used a T-tap to make the connection.

 

[AEC]

Just did this on my 2003 as well exactly as Ayune describes for the "later year" trucks. The following post about replacing the junction box does a great job showing how to get to these connectors. Pro tip be smarter than me and use a multimeter to make sure your pins have been connected per the Ayune mod before putting everything back together, ask me how I know... Also make sure you count the number of pins on the connectors to make sure you are tapping into the correct wires! Both connectors look very similar and there are many same color wires down there, use the 1A pin diagram it only has 9 pins in the middle blocks! Use the ribs in the diagram to make sure you are looking at the connector in the right orientation.
2005 LX470 Main Junction Block Replacement - https://forum.ih8mud.com/threads/2005-lx470-main-junction-block-replacement.1003958/

Also combining Ayune's post with this mod will allow you to have full control over your fog lights! (use with high beams on)
Fog Light Switch Rewire for High Beam Use - https://tlcfaq.com/main/2012/04/rewire-your-fog-light-switch-to-work-with-high-beams-on/

Here's mine with low beam off

With low beams on

And with high beams on!