Sorry! Another fog light question. - Toyota Yaris Forums

Jrilla · 08-22-2009, 08:50 PM

I just spent an hour reading through fog light threads and I didn't see this exact question: I installed my own fog lights by cutting holes in my 09 Sedan trim pieces and I used the relay in the fuse block method and my own toggle switch to connect pin 3 and 4 on the headlight stalk. Everything works fine, except I din't realize the fogs would only work with the headlights on and would not work with only the parking lights or even the high beams. This is not a big deal, but I would like the option of turning them on anytime the ignition is on. I am pretty sure I would settle for then being able to be turned on when the parking lights are on.

All I have seen so far in my reading has been to skip the connection to pin 3 and 4 and run wires through the firewall. I am perfectly comfortable and knowledgeable of that procedure, and i even found out how to trigger the cluster light if I still want that after abandoning the pin 3 and 4 method.

I guess I am wondering if there is a way to trick the car into thinking the headlights are on, or something like that. I tested pin 3 and 4 and they are constant 12volts+ even with the key off. The only change that happens is one of them (I forget which right now) turns into a ground signal when the headlights are on and only when they are on.

I am very familiar with 12volt wiring, but my problem is I learned it all on my own and I never really learned much theory. My first thought was that all I need to do is ground the wire that changed to ground when the headlights are on, but then I would still need to connect the two wires (3 and 4). There is something wrong with this idea I'm sure, but I think a little more knowledge of the whole setup would help. like what is causing that pin 3 or 4 to change to ground when the headlights are turned on?

Any ideas? If I missed the thread that talks about this, I apologize and if you could point me in the direction of such thread, I would appreciate it greatly.

CTScott · 08-22-2009, 10:02 PM

This was discussed a while back in a fogs with high beams thread, but the simple answer is take the wire from your switch off of pin 4 and go straight to ground with it (leave the other on pin 3 though). This will bypass the DRL module and the logic for fogs only on with low beams.

Jrilla · 08-23-2009, 01:36 PM

Thanks. Just to clarify, will the switch be in complete control of the fogs then regardless of the ignition being on or off?

CTScott · 08-23-2009, 01:54 PM

Quote:

Originally Posted by Jrilla

Thanks. Just to clarify, will the switch be in complete control of the fogs then regardless of the ignition being on or off?

correct

Jrilla · 08-23-2009, 02:25 PM

OK, thanks for the help. I will either keep it the way it is, or if I decide I want the option of turning them on with the parking lights or high beams I will just put a relay inline on the ground wire to the switch that either closes the circuit when the parking lights are on or maybe I'll use the ignition as the trigger so I can use the fogs as daytime running lights if I want.

Thanks again for the help.

08-22-2009, 08:50 PM	#1
Jrilla Drives: 09 Yaris 4Dr Sedan Join Date: Aug 2009 Location: Fargo, ND Posts: 20	Sorry! Another fog light question. I just spent an hour reading through fog light threads and I didn't see this exact question: I installed my own fog lights by cutting holes in my 09 Sedan trim pieces and I used the relay in the fuse block method and my own toggle switch to connect pin 3 and 4 on the headlight stalk. Everything works fine, except I din't realize the fogs would only work with the headlights on and would not work with only the parking lights or even the high beams. This is not a big deal, but I would like the option of turning them on anytime the ignition is on. I am pretty sure I would settle for then being able to be turned on when the parking lights are on. All I have seen so far in my reading has been to skip the connection to pin 3 and 4 and run wires through the firewall. I am perfectly comfortable and knowledgeable of that procedure, and i even found out how to trigger the cluster light if I still want that after abandoning the pin 3 and 4 method. I guess I am wondering if there is a way to trick the car into thinking the headlights are on, or something like that. I tested pin 3 and 4 and they are constant 12volts+ even with the key off. The only change that happens is one of them (I forget which right now) turns into a ground signal when the headlights are on and only when they are on. I am very familiar with 12volt wiring, but my problem is I learned it all on my own and I never really learned much theory. My first thought was that all I need to do is ground the wire that changed to ground when the headlights are on, but then I would still need to connect the two wires (3 and 4). There is something wrong with this idea I'm sure, but I think a little more knowledge of the whole setup would help. like what is causing that pin 3 or 4 to change to ground when the headlights are turned on? Any ideas? If I missed the thread that talks about this, I apologize and if you could point me in the direction of such thread, I would appreciate it greatly.

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08-22-2009, 10:02 PM	#2
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	This was discussed a while back in a fogs with high beams thread, but the simple answer is take the wire from your switch off of pin 4 and go straight to ground with it (leave the other on pin 3 though). This will bypass the DRL module and the logic for fogs only on with low beams.

08-23-2009, 01:36 PM	#3
Jrilla Drives: 09 Yaris 4Dr Sedan Join Date: Aug 2009 Location: Fargo, ND Posts: 20	Thanks. Just to clarify, will the switch be in complete control of the fogs then regardless of the ignition being on or off?

08-23-2009, 02:25 PM	#5
Jrilla Drives: 09 Yaris 4Dr Sedan Join Date: Aug 2009 Location: Fargo, ND Posts: 20	OK, thanks for the help. I will either keep it the way it is, or if I decide I want the option of turning them on with the parking lights or high beams I will just put a relay inline on the ground wire to the switch that either closes the circuit when the parking lights are on or maybe I'll use the ignition as the trigger so I can use the fogs as daytime running lights if I want. Thanks again for the help.