2012 Fog relay

[Absolutely Red 12]

I cant seem to find the fog relay plug.
Remember his is a 2012, all previous diagrams dont mean squat!!

BTW, my 2012 already has a fog light loom under the hood!!

[CTScott]

There is none on the 2012. The fog light relay is built into the body ECU.

To see if it is enabled on your car, you can jump pin 3 to pin 4 on the headlight switch connector D106. Pin 3 will be brown or green (depending on if you have the OEM alarm) and Pin 4 will be green.

Jump those wires and have the ignition on and the headlight switch in the low beam position. If the fogs don't light then the relay is not in there. For the 2nd gens for instance the integrated relay for the power windows and locks is not present on cars that were not built with them (and there are different part number for the body ECU).



D106.jpg

[Absolutely Red 12]

Originally Posted by CTScott

There is none on the 2012. The fog light relay is built into the body ECU.

To see if it is enabled on your car, you can jump pin 3 to pin 4 on the headlight switch connector D106. Pin 3 will be brown or green (depending on if you have the OEM alarm) and Pin 4 will be green.

Jump those wires and have the ignition on and the headlight switch in the low beam position. If the fogs don't light then the relay is not in there. For the 2nd gens for instance the integrated relay for the power windows and locks is not present on cars that were not built with them (and there are different part number for the body ECU).



Attachment 48579

CTScott

Thank you, I was getting that impression from reading the Prius C forums.

The fog harness behind the bumper is already there, as is the fog fuse.

I do not have the OEM alarm, so brown to green?
What wire is the parking light, if I cheese to not use low beam?
Is the illustration pin side, or wire side?


Again, thank you!

[CTScott]

Originally Posted by Absolutely Red 12

CTScott

Thank you, I was getting that impression from reading the Prius C forums.

The fog harness behind the bumper is already there, as is the fog fuse.

I do not have the OEM alarm, so brown to green?
What wire is the parking light, if I cheese to not use low beam?
Is the illustration pin side, or wire side?


Again, thank you!

If you have the alarm or DRLs - Green to brown.
If you have neither alarm nor DRLs - Green to Green.


The connector illustration is looking at the pin side of the connector.


For the parking light turn on, it is a bit more complicated for the 2012, as for the ones with DRLs, that functionality is built into the body ECU, so it will be completely different for DRL vs. non-DRL Yaris. I would start with seeing if it works at all on a non-factory equipped car.

[Absolutely Red 12]

Originally Posted by CTScott

If you have the alarm or DRLs - Green to brown.
If you have neither alarm nor DRLs - Green to Green.


The connector illustration is looking at the pin side of the connector.


For the parking light turn on, it is a bit more complicated for the 2012, as for the ones with DRLs, that functionality is built into the body ECU, so it will be completely different for DRL vs. non-DRL Yaris. I would start with seeing if it works at all on a non-factory equipped car.

Got it, will let you know tonight.

Thanks again!

[Absolutely Red 12]

Pins 3&4 are violet, and green.
Jumping them does not turn the fogs on.
Using DVOM shows no voltage coming from either wire when turning on the
headlights.

[Absolutely Red 12]

OK. DISREGARD my last post.
I forgot to turn on the ignition DOOOOHHH!

Jumping the purple and green wires at 3&4 made the fogs go on!!
The light on the dash also works!!

Time to get some taps, and wire the switch.


Now taking this one step further, how do I make it work with park, low, high.

CT Scott, thank you for the help, also in advance!!

[CTScott]

Originally Posted by Absolutely Red 12

OK. DISREGARD my last post.
I forgot to turn on the ignition DOOOOHHH!

Jumping the purple and green wires at 3&4 made the fogs go on!!
The light on the dash also works!!

Time to get some taps, and wire the switch.


Now taking this one step further, how do I make it work with park, low, high.

CT Scott, thank you for the help, also in advance!!

Do you have DRLs?

[Absolutely Red 12]

Originally Posted by CTScott

Do you have DRLs?

No DRLs.

Also now using a PIAA switch, as the cheap Chinese Toyota looking switch would not allow the fogs to turn off.

New switch is a 3 wire, internal lighting, when on. It also allows the dash icon to turn on!!

[CTScott]

Originally Posted by Absolutely Red 12

No DRLs.

Also now using a PIAA switch, as the cheap Chinese Toyota looking switch would not allow the fogs to turn off.

New switch is a 3 wire, internal lighting, when on. It also allows the dash icon to turn on!!

You should use a four, not three wire switch. The illumination should be isolated from the switching.

I just noticed that for both the DRL and non-DRL Yaris the fog relay coil is tied directly to the body ECU internally in such a way that it prevents the fogs from turning on except when it decides it is OK to. You would have to either do some surgery on the body ECU or use an external relay and rewire the fogs to it to override that behavior.

[Absolutely Red 12]

Originally Posted by CTScott

You should use a four, not three wire switch. The illumination should be isolated from the switching.

I just noticed that for both the DRL and non-DRL Yaris the fog relay coil is tied directly to the body ECU internally in such a way that it prevents the fogs from turning on except when it decides it is OK to. You would have to either do some surgery on the body ECU or use an external relay and rewire the fogs to it to override that behavior.

Ok, Ill leave it like this for now.
The Chinese switch was a four, with isolated illumination. Wouldn't allow the fogs to turn off!! The three wire works as expected, Ill get another 4 wire to avoid future issues.

Thanks a bunch.

[CTScott]

Originally Posted by Absolutely Red 12

Ok, Ill leave it like this for now.
The Chinese switch was a four, with isolated illumination. Wouldn't allow the fogs to turn off!! The three wire works as expected, Ill get another 4 wire to avoid future issues.

Thanks a bunch.

The one that came with the kit has some internal circuitry which ties the switching and illumination together. What you want is one where the two are truly isolated.

[Absolutely Red 12]

Philips CrystalVision Ultra 9003, and H11 in the Headlights and fogs.

[Absolutely Red 12]

Originally Posted by CTScott

You should use a four, not three wire switch. The illumination should be isolated from the switching.

I just noticed that for both the DRL and non-DRL Yaris the fog relay coil is tied directly to the body ECU internally in such a way that it prevents the fogs from turning on except when it decides it is OK to. You would have to either do some surgery on the body ECU or use an external relay and rewire the fogs to it to override that behavior.

Scott,

The green wire is the trigger when the head lights lights go on, the violet loops to the other row. Looks like the Violet triggers the fog realy, and dash light.
Im having difficulty finding the wire that is live when the park/low/high get selected.

Do you have a wiring diagram for 2012??

[CTScott]

Originally Posted by Absolutely Red 12

Scott,

The green wire is the trigger when the head lights lights go on, the violet loops to the other row. Looks like the Violet triggers the fog realy, and dash light.
Im having difficulty finding the wire that is live when the park/low/high get selected.

Do you have a wiring diagram for 2012??

The green wire is "activated" by the Body ECU, when it decided that it is OK to let the user turn the fogs on. Once it is active, shorting it ground (which is what the violet wire is tied to) at that time allows power to flow through the fog relay coil.

The blue wire in pin 18 is the one that is activated when the park or headlights are on. It is 12V with them off and then switches to ground with them on.

[Shroomster]

So dumb question, and sorry to necro-bump, but all I need to do in theory is get the foglight kit, plug the lights into the pre-existing harnesses, then tap the two wires to the switch and install it in place of a delete plug?

[CTScott]

Originally Posted by Shroomster

So dumb question, and sorry to necro-bump, but all I need to do in theory is get the foglight kit, plug the lights into the pre-existing harnesses, then tap the two wires to the switch and install it in place of a delete plug?

Correct

[Shroomster]

Originally Posted by CTScott

Correct

Woot! Time to see what kind of deal I can get on an o.e.m kit from dealer through my job!