fog lights

I was taught to use only the low beams of the headlights while driving in the fog and to never use the high beams in those situations.

By the way, the Prius' fog lights will lit only when the low beams of the headlights are on. They go off the moment you switch to the high beams.

 

>>Has anyone dealt with the issues of re-wiring the fog lights to work without headlights?

I gather this may not be legal, but I can tell you for sure it is necessary! <<

Honestly, this has been discussed, but they are driving lights, not real "fog" lights. Fog lights are usually yellow. The color helps cut the fog.

 

Hum. They do call them foglights. I just think the yellow would help more.
I did drive in some fog here with the HIDs. Probably not as bad as what you experienced. Didn't suck much more than normal.

 

You may have meant it; however, you did not write it quite that way.

This is what you wrote:

The words "Low beams" did not appear anywhere in that post.

 

wow someone else who found the fog lights one notch better than p**s useless. This subject was beaten to death last winter and spring on PC, do a search on them and read up. Yup fancy junk! useless in real fog.

 

I understood him fine.

The HIDs light up the same intensity, 'low beam' or 'high'. A shutter masks the top rays in low beam mode, and move out of the way in high beam, thus throwing out light upward as well.

So with that much light, fog can definitely reflect it back in all directions.

I agree, the fog lights are useless. They are drowned out with the HID lights. They'd be more useful if they could be turned on without headlights.
And they will seem yellow compared to the more white HIDs.

 

<div class='quotetop'>QUOTE(tomdeimos\";p=\"63550)</div>

The Prius replaced my 1987 MBZ 300E which I drove for 17 years and four months for a total of almost 217,000 miles.

<div class='quotetop'>QUOTE(DanMan32\";p=\"63553)</div>

So, DanMan, you are the expert in these matters, is it doable?

 

Hmm, a challenge. I love it!

It looks like one end of the fog switch on the combo switch connects to the body ECU, which in turn engages the fog relay to turn the lights on.

Now the other side of the fog switch connects to an orange wire, which connects to a blue wire through a terminal block, and goes to the low beam side of the headlight dimmer, which isn't used for anything else. It seems if you feed ground to the orange wire after disconnecting it from the junction block, the fog light could come on any time. At first I thoght that might defeat the auto off, but I think the body ECU will turn it off automatically no matter what you feed to to the fog terminal.

Will have to do some trial runs.

 

Someday I'll tackle full-Auto DRL, but I suspect I'll have to get the DRL ECU and sensor. I am suspecting that may not be cheap, and I'll have to get that from Canada.

 

Well, I tried to ground the sky blue wire, pin 4 on the combination switch, which goes to the body ECU for the fog light. Unfortunately, the body ECU is too smart, and won't turn on the fogs unless the headlights are on low. They won't come on with highbeams even if I ground the SB wire going to the ECU, bypassing the dimmer switch, so I don't know why they make use of the low beam switch for the fog.

So Tom, jumpering pins 14 and 15 won't do it.

We could bypass the body ECU and turn on the fog relay ourselves. If we don't mind turning on the fogs only when the tail light is on, then we can jumper the SB wire on pin 13 at the ECU to the yellow wire at pin 17 on the ECU. The tail lights go off automatically, and the fog relay gets its power from the tail lights, so it will cut out automatically, and turn off the fogs.

 

<div class='quotetop'>QUOTE(Frank Hudon\";p=\"63552)</div>

Are they ever. Purely cosmetic and better left off. A "real" foglight, like a Hella with a yellow lens, would work wonders.

You could wire the real foglights on a separate circuit, and put the headlight switch to Park. I'm not sure if that would be legal in the U.S. or Canada though.

Headlight aim is very important for driving in snow, rain, and fog. After I had my headlights properly aimed at an Autopac-certified bodyshop using a digital reference aiming machine, nighttime performance in poor conditions was much improved.

If the headlights are dirty with slush/salt or road grime, the light can be diffused or diffracted. I've noticed this driving on slushy roads in Winnipeg. I frequently have to stop at a gas station to squeegee the headlights. Here is wishing for headlight washers/wipers.

 

DanMan, Please let us know when you succeed. I asked Wonderful Wayne to look into this a year ago and he said he would. But he has dissappeared. You really want only the fog on when you need near illumination. When really needed it does not light the road very far, but enough so you can stay on the road while you slow down.
I know I can get an ign switched hot to switch an add-on relay and bypass the OEM, but there oughtabe a better way.