DIY yaris III fog lights installation

[CTScott]

OK - Here's another thought:

Looking at the EWD, the four connection points of the relay are all accessible at easier to get at points. With that in mind you could use a normally open automotive relay and connect it as follows:

Coil + to the green wire in connector 3A pin 55 of the body ECU
Coil - to the pink wire in connector 3A pin 15 of the body ECU
Contact common terminal to the beige wire in connector 3A pin 4 of the body ECU
Contact normally open terminal to the beige wire in connector F3 pin 12 of the instrument cluster

[karloslatynos]

At least thanks to the master now we know, that there is another way of making front fogs working in 3-rd yaris.

I went to the dealer today and they only said the front fog relay is accessable without removing upper dash panel (HALLELUYAH) rather through the glove box. Now I can confirm that.

To get to the front fog relay nest we need to remove the glove box (to have the access) and the front dash panel (RHD) to be able to see (some kind of torch is also required)

I am waiting now for relay to be delivered. I'm gonna do some photos & descriptions. See you soon.

[karloslatynos]

Relay plugged in, front fogs working but...

When jumped green to light green its kicking itself out...

link to the video demonstration below

https://www.youtube.com/watch?v=gc-J...ature=youtu.be

[CTScott]

Can you post a picture of the wires going into the headlight switch?

[karloslatynos]

Originally Posted by CTScott

Can you post a picture of the wires going into the headlight switch?

as requested

[karloslatynos]

057A.jpg

058B.jpg

060C.jpg

062D.jpg

065E.jpg

066F.jpg

[CTScott]

OK. All of the wires are where I would expect them to be.

The body ECU is involved in the process of switching the fogs on. The front and rear fog switches are inputs to the body ECU and it in turn drives the relays for them. From what you are seeing it may be that it has enough smarts to want them to truly be separate inputs. Try just jumping the front fog's dark green wire to the brown wire (which will allow the fronts to turn on) and then turn on the rears as well as see if they both stay on.

[karloslatynos]

Originally Posted by CTScott

OK. All of the wires are where I would expect them to be.

The body ECU is involved in the process of switching the fogs on. The front and rear fog switches are inputs to the body ECU and it in turn drives the relays for them. From what you are seeing it may be that it has enough smarts to want them to truly be separate inputs. Try just jumping the front fog's dark green wire to the brown wire (which will allow the fronts to turn on) and then turn on the rears as well as see if they both stay on.

All of the wires are in place as they should be. When jumped dark green to the brown, front fogs are automatically switched on when turn the headlights. The rears operate as normal.

When swapped over light green with dark green, none of fogs are able to switched on.

[CTScott]

Originally Posted by karloslatynos

All of the wires are in place as they should be. When jumped dark green to the brown, front fogs are automatically switched on when turn the headlights. The rears operate as normal.

When swapped over light green with dark green, none of fogs are able to switched on.

OK. So, the body ECU is definitely not happy with them connected together, so you will have to add another switch or obtain one of the stalks with both switches.

[Eforno]

I know this post is rather old, but are 3rd gen Yaris in the US pre-wired like the EU ones?

[CTScott]

Originally Posted by Eforno

I know this post is rather old, but are 3rd gen Yaris in the US pre-wired like the EU ones?

Yes. There is a DIY thread for 3rd gen US ones.

[Eforno]

Originally Posted by CTScott

Yes. There is a DIY thread for 3rd gen US ones.

Thanks! Are you talking about this one?

[Skriptenfresser]

Hello everyone! Although this topic is rather old, I want to answer, since I came here using Google.

I am also thinking about adding front fog light, so I read this thread and perhaps I know the reason for your car's behaviour, I want to give a deeper insight and there MAY be a solution.

At first, we need some general explanation regarding the wiring.
The front and rear fog lights are both controlled by the Body ECU. This ECU controls two relays, which simply connect these lights to the 12V supply. The ECU switches the lights on, when the user requests this by turning a switch on the light stalk. Usually (if factory fitted!), there is ONE(!) multi-position switch for the front and rear fog lights. This switch has three positions:
- Off
- Front Fog Light
- Rear Fog Light

The "Off" and "Front Fog Light" positions snap in, the switch keeps its position there. (like a typical on/off switch). But the "Rear Fog Light" position is DIFFERENT. The switch does not snap in this position, there is a spring pushing it back (like a push button). So if you turn your light stalk switch to "Rear Fog Light" for the first time, the rear Fog light turns on and the switch returns into the previous position (but still keeping the rear fog light on). If you turn it again, the rear fog lights turn off again. All fog lights turn off, if you turn the switch back to "off".

The key point is: The front fog light switch position connects the wire PERMANENTLY to Ground, as long as the front fog switch is in its position. But the rear fog light switch position outputs only a brief connection to GND (as long as the switch is held in the "rear fog light" position).
Furthermore, it looks like the ECU automatically turns off the rear fog lights, when it sees, that the front fog lights are turned off (=its wire is not longer grounded).

I do not think, that the ECU is intelligent enough to KNOW, that both wires are connected and somehow does something to prevent you from doing this.
What you are seeing is the correct behaviour, as expected from the wiring explained above.

What happens is:
- You connect both green wires together
- You bring the rear fog light switch into the "on" position for a short time (since the switch returns into the original position afterwards)
- This connects both wires to GND for a short time
- In the very first moment, the ECU sees the front fog light wire connected to GND and switches on the front fog light
- The ECU also sees the rear fog light wires connected to GND and switches on the rear fog lights as well
- In the next moment, the switch returns into its original position and the connection to GND breaks
- The ECU sees, that the rear fog light switch returned (no action taken)
- The ECU ALSO sees, that the front fog light switch ALSO returned and switches off the front fog light. The ECU thinks, you turned the light stalk switch to "off". The rear fog light is therefore also switched off, since this is the intended behaviour with the original light stalk (the ECU now thinks, you are using this one!)


There may be some solutions:
- Use the original light stalk with the switch for BOTH fog lights. Should work out of the box now.
- Add an additional switch for the front fog lights (on/off switch with two real positions, not a push button!), but that is perhaps not what you want. Nevertheless, this is the solution I would use, since I need to control the front and rear fog lights independently (legal reasons, some situations allow front fog lights but not rear fog lights on).
- Build a more complex circuit: Connect a toggle relay (I am not sure about the name) to the rear fog light switch, so the relay changes its state each time, the switch is actuated. The relay then switches the front fog light wire of the light stalk to the ECU.

I hope this clarifies the behaviour.

//EDIT:
Today, I successfully verified my post on my car (Toyota Yaris Hybid, latest version, bought in May 2015).

Another very interesting fact is that the front fog fuse as well as the front fog relay were already in place. Maybe the relay is integrated into one of the ECUs, I was not able to locate it. I heard it clicking and then I was able to measure +12V at the front fog light connectors. Since I am the first driver of this car, this must already have been factory fitted.
So the upgrade becomes more simple: I do not have to buy a relay or do much wiring. I will just have to add a switch and mount the light. :-)

[karloslatynos]

well explained. Thank you

[neofitos]

Hello everybody,

I am from Greece!
I have a 2012 Mk3 Yaris, made in France.

I bought an ebay fog light kit(lamps wiring and switch), installed the lamps, the wiring already exists.
I cannot do the connection inside the cabin for the switch.

I have read all the threads for ebay fog lights. I put a fuse for front fog lights under the dash panel .

Connecting pin 3 to pin 4 in the stalk light switch will not light my front fog lights.
Everybody says that relay already exists(i cannot see it).What am i doing wrong??
My Yaris has alarm installed by Toyota, i dont know if this helps somewhere.Furthermore my genuine toyota light switch installed on the car has only a spring powered switch for the rear fog lights . There is no position in the geuine switch for the front fogs.

Shall i buy a new toyota switch with two positions??
Every opinion is appreciated! I have been searching everywhere, Toyota here in greece say that they do not help me because it is aftermarket and if sth goes wrong i will blame them.(I cannot understand that since the wiring already exists , there is nothing aftermarket except the plastic cover from the lamps)

[karloslatynos]

Originally Posted by neofitos

Hello everybody,

I am from Greece!
I have a 2012 Mk3 Yaris, made in France.

I bought an ebay fog light kit(lamps wiring and switch), installed the lamps, the wiring already exists.
I cannot do the connection inside the cabin for the switch.

I have read all the threads for ebay fog lights. I put a fuse for front fog lights under the dash panel .

Connecting pin 3 to pin 4 in the stalk light switch will not light my front fog lights.
Everybody says that relay already exists(i cannot see it).What am i doing wrong??
My Yaris has alarm installed by Toyota, i dont know if this helps somewhere.Furthermore my genuine toyota light switch installed on the car has only a spring powered switch for the rear fog lights . There is no position in the geuine switch for the front fogs.

Shall i buy a new toyota switch with two positions??
Every opinion is appreciated! I have been searching everywhere, Toyota here in greece say that they do not help me because it is aftermarket and if sth goes wrong i will blame them.(I cannot understand that since the wiring already exists , there is nothing aftermarket except the plastic cover from the lamps)

I think if you have used the existing wiring circut (as I did on mine) a new (second hand) switch/stalk is the best solution. Its going to look like factory installed. By the way can you send a link of your ebay purchase? Does it have any manual?

[neofitos]

thanks a lot for your quick answer karlos!!

this is the one that i bought.there was no manual. i want to use the existing wiring

http://www.ebay.com/itm/380995092067...%3AMEBIDX%3AIT

where should i connect the new switch? what kind of switch should i buy?
do you have any link ?

[neofitos]

Sorry for the delay , my last post was not posted(dont know why).

thank you karlos for youw answer!

http://www.ebay.com/itm/380995092067...%3AMEBIDX%3AIT

this is the one that i bought.
i want to use the existing wiring.
that type of switch should i buy? there should i connect it?