DIY: How-To Enable “Anytime” Fog Lights for $15 or Less
DIY: How-To Enable “Anytime” Fog Lights
2007 – 08 Tundra
For $15 or Less
Design by Daless2
Note: I have made updates to these instructions to give you a choice as to how your Fog Lights will perform, based on Ignition Key Position.
Your Options Are:
Option “A” = Fog Light Operate Independent of Ignition Switch Position
Option “B” = Fog Lights “Off” when Ignition Switch is Turned “Off”
Option “C”= Fog Lights “Auto Off” 2-Hours after Ignition Switch is turned “Off”
You get to pick the option of your choice.
I have also added a Version Number to the file name FogLightsVx.pdf where x = a number. The higher the number is, the more current the document.
Overview of Factory Fog Lights
The Factory Fog Light Switch, mounted on the stalk, does not turn the Fog Lights “On”.
Instead, when you turn this switch “On” it makes a “Request”, (via a ground signal) to the Main Body ECU to turn the Fog Lights “On”.
The Main Body ECU then decides, based on a set of rules, if it will supply a ground to the Fog Light Relay “coil”, or if it will supply +12 volts to the other side of the Fog Light Relay “coil”.
The Main Body ECU must supply both a “ground” and a “voltage” at the same time, for the fog lights to turn “On”.
The “rules” which the MB-ECU applies when you “request” the Fog Lights be turned “On” are as follows:
q Fog Lights cannot be turned on by themselves
q Headlights Lights must be “On” for Fog Lights to turn “On”.
q High Beam Headlights “On” cause Fog Lights to “Turn Off”
Basic Design Description
More then a few Tundra owners have expressed an interest in being able to turn the Fog Lights “ON” anytime they want, regardless of the rules that apply to the truck as it comes from the factory.
This design will do this for you by divorcing the Factory Fog Lights both physical and electrical from the control of the Main Body ECU.
This is accomplished by physically removing the Factory Fog Light Relay, installing and wiring up a New Bosch Type Automotive Relay and cutting one wire.
Please Note:You must be willing to cut this wire. DO NOT under any circumstances think you can just “tap” into this wire. If you do you will put your Main Body ECU at unknown risk..
If you want this function bad enough, step up to the plate, suck it in, be brave, and snip it!
As a second feature, this design will allow you to put your Fog Lights back to the way it works now (factory) in about 5 minutes using no tools. This includes the cut wire.
I performed this modification on one 2007 Tundra’s and one 2008 Tundra this weekend.
It works.
If you are reading this as a part of a forum thread, please double click on the “FogLightsVx.pdf” file located at the bottom of this post to view and download the “How-To” instructions.
Note2: Eddie has designed an alternative means of turning on the Tundra Fog Lights.
Being I have the pictures of the connectors involved and their locations I have elected to document Eddie’s design.
Eddie’s single wire solution will enable your Fog Lights to be “On” any time the Tundra Main Light Switch is “On” in any position.
I test installed Eddie’s solution on my Tundra (2007) and can verify it works as designed.
If you are reading this as a part of a forum thread, please double click on the “FogLightsEddieVx.pdf” file located below.
I hope some find this useful.
Have a great night.
Frank
Last edited by daless2; 04-16-2008 at 07:31 PM.
Reason: Edited to Add Options to Fog Light / Ignition Switch Operations
Re: DIY: How-To Enable “Anytime” Fog Lights for $15 or Less
Pedro66, I’m afraid I won’t be able to help you on the “Bling Lights” you have installed.
These instructions will only work for the Factory Installed lights, using the Factory switch, wiring harness and Main Body ECU to control the lights.
Cutting the PINK Wire
YOU MUST CUT the PINK Wire.
DO NOT perform this modification if you are not willing to cut the Pink Wire.
Tapping into this wire, instead of cutting it will expose the Main Body ECU to +12 volts on a terminal that is designed to see only a “ground”. The effects of doing this are unknown, and probably will be “BAD”.
Please read that “Putting the Main Body ECU at risk.”
Cutting the wire eliminates ALL RISK.
Thank you for asking this question. I thought I had it covered in the instructions. I will make a change to the instructions later putting more emphasis on this requirement and why.
Fog Lights On/Off with Ignition Switch
About a week or so ago, in another thread on this forum I asked how folks would like the Fog Lights to work.
My understanding was most wanted these light to work from the stalk switch “Anytime” this Fog Light Switch was in the On Position.
That is what this design will do. Ignition On or Off, fog lights work.
Leave fog lights on when you take the key out of ignition and go to work….they will stay on till the battery goes dead.
That said, the Factory Fog lights could be made to Turn Off with the Ignition Switch,
Or
Turn Off “automagically” Two Hours after the Ignition Switch has been turned off.
Either of these two options will involve routing a second wire, from the new relay you are adding, into the cab of your truck where it will tap into an existing wire.
I’ll get this done a bit later and update the document to reflect either of these two options.
That said I have a busy day here today. Heck I’m already ready for a nap. (Don’t get old!) If I don’t get to it today I will do so this evening.
Thank you for your kind words. Please feel free to add this to the DIY thread. I'd enjoy seeing other get value from this.
HOWEVER, Please note, I just updated the PFD File to include Options. You might want to pick up the new file as I think it may be of more value to others.
Re: DIY: How-To Enable “Anytime” Fog Lights for $15 or Less
This is great!! Thanks for taking the time to check into this and do the wite/rewrite/rerewrite. I've got V1 and V3 saved for later reference.
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Re: DIY: How-To Enable “Anytime” Fog Lights for $15 or Less
Quote:
Originally Posted by daless2
Thank you for your kind words. Please feel free to add this to the DIY thread. I'd enjoy seeing other get value from this.
HOWEVER, Please note, I just updated the PFD File to include Options. You might want to pick up the new file as I think it may be of more value to others.
Have a great day,
Frank
DIY Sticky updated with new version.
Thanks.
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My Truck: 2005 Tundra, 2UZFE. 4WD. AccessCab. Spectra Blue Mica (8M6). TRD. AT. CC. CK. DZ. FE. AW. LD. OF. TO. VP.
DIY: How-To Enable “Anytime” Fog Lights for $15 or Less
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