DIY yaris III fog lights installation

[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.