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Fog lights only on with full headlights are totally useless. Is there a fix existing where I could power the fog lights with the parking lights?

[b]Second topic[/b]. I discovered I could, while driving, change my NAV destination by entering any of the six registered destination points. It won't allow you to go to the second page while driving. I am aware of Coastal's fix and am patiently awaiting delivery.
Serge

There is extensive discussion on PriusChat about this. You can put a diode between pins 17 (yellow) and 13 (sky blue) on connector B5 going to the body ECU in the driver J/B. The diode is needed rather than just a jumper, as otherwise you will create a latch condition when the body ECU sends a ground to the fog relay coil, it will also unwittingly send the ground to the fog switch input. This will allow the auto off to still function, though you will at least have to have your taillights on.

Thanks Dan, you are always so helpful. I appreciate it.

Sorry Dan, I am sure it's my fault and/or impatience, but could you send me a link to a TechDesc on how to do this, please?
( I only spent ~20 minutes on priuschat searching while working on some other stuff, I confess )

Thanks,
Attila

Here's the link to the discussion and details on priuschat:

http://www.priuschat.com/forums/fog-lights-vt6525.html

Oh, thank you.

So, Dan, just to summarize :
1. No cutting of any wires is needed.
2. Put a diode in, where cathode goes to pin 13, and the anode to pin 17.

About this diode, what kinda nominal zener voltage and surge current you might be proposing?

Attila

Not a zener diode. A small rectifier diode will do, maybe .5A should be plenty. All you are doing is operating a relay coil. Also the wires to the combination switch are pretty tiny, I doubt they could carry any appreciable current, and others have operated the fog relay directly.

No cutting necessary, if you can get both leads of the diode make contact with their respective connector from the back side.

I'll be honest, I haven't done this yet, so I have not taken into account for the physical feasability, only the electrical feasability.

Tried for a while to "plug" a diode in, no luck.
Decided to do it the "less time consuming" way... Works great!

http://www.vassfamily.net/ToyotaPrius/F ... ogMod.html

Thanks,
Attila

Yes, that would work too. I was trying for the least invasive idea; IE not having to tap into wires. However, tapping would work just the same.

Yikes Attila!! Glad that worked for you, but I'd much prefer the 'shove a diode' technique if that could be worked out without disassembling the entire dash! Got the willies seeing all those connectors unplugged.

I think I'll wait for an idiot proof mod on this one.

Here it's illegal to turn on foglights unless you have <100m visibility, thank goodness.

My understanding is that the US and the UK have different definitions of fog lights. In the US, the factory ones on the Prius are small, white lights that are in the front bumper (low to the ground). My understanding is that in the UK, the fog light(s) are in the rear bumper...

I don't quite get the "thank goodness" part, but your foglights might be different than here than. They are most certainly less powerful ( and cheaper to replace ) than the HID lights. So having them turned on vs. the HID is actually not a bad thing...

mrv, you're referring to the rear foglight which is a single (occasionally dual) bright red light in the rear. It may or may not be in the bumper.

Some front foglights are bright, some aren't so we can't jump to a conclusion that all foglights are bad

I hear you. I spent about 2 hours trying to fit the diode without having the dash taken apart. I did several soldering options to strengthen the legs of the diode, I even shaved'em so that they may fit next to the present wires, I even soldered needles on'em etc...

The other problem is space of course. If I only had a hand and a body of a 2 year old for the time of this mod, I might have been able to do it, but again, shoving the diode in to B5 does not seem like an easy thing to do.

So, I think the best solution so far is the way 'totavi99' had it on priuschat...

Again, at least I confirmed that DanMan32's diode solution is not only feasible on paper, but it works in practice as well...

Attila