Rear window defogger -- Timed version available?
 

Seems to me that I saw a post a couple of months ago about replacing the existing manually controlled rear window defogger with a timed one... can anyone point me to the post? If not, does anyone know if this is a possibility? Now that I've got manual control over running the A/C during defrost, this item is the next one on my "hit list".

I haven't found a timed defrost button. Considering the defrost and AC buttons are combined, might be hard to do.

We're counting on you, and have faith in you!!! ;)

You can do it!! LOL!

CLARIFICATION -- I'm talking about the rear-window DEFOGGER (demister) button -- not the front defroster. This is a separate control and has nothing to do with the AC/vent controls. Currently (on the US Fit anyway), you have to remember to turn it off manually instead of having it turn itself off automatically. I thought I remembered seeing that someone had swapped out the current button with one from another Honda (but which?) that had a timed feature on it. I searched around in the posts but can't find it so perhaps I was just dreaming?

This sure would be nice if it was available! Even our '02 Forester has this :)

I was under the assumption that the Fit defrost button was timed...After 15min it cuts off...

Like I stated before, the North American Fit uses a combined AC and rear defrost button. Af first Honda.ca website lead to believe that the Canadian Fit had a timed function, but it doesn't. See part #1?

http://collegehillshonda.softwareglo...4sln70_b17.gif

Most Hondas have an integrated rear defrost timer built into the fuse box with the wiper controls, something the Fit seems to be lacking.

Thanks for the drawing detail... unless the existing 2-position defogger switch can be substituted with a momentary there isn't an option that I can see for going to a timed defogger. I was intrigued by the pins/screws marked 3 & 4 in the exploded view -- is there a bill of material that calls these out and describes them?

Sigh...

i beleive that 3 & 4 indicate the bulbs and holders that provide the switch on light and the ambient light when you have your headlights on.

While I haven't taken the Fit switch a part I have had success in converting other switches from 2 position to momentary. Once we have that adding the timer function shouldn't be too hard. Any idea on the switch's price? Also how/where can we get a schematic? I really want to make the rear wiper intermittent. What would be really cool is to have the front and rear trigger at the same time.

I haven't gone any further on looking into timed defrost... I did quite a bit of work on intermittent rear-wiper - to the point that I have demonstrated that my approach works (see alternate post) - but I haven't pulled enough of the final circuitry together to make it "real" (I'm more of an embedded software geek than a hardware geek).

I would think you could add a timer function to the rear defogger by adding a time-delay relay to the switch circuit. Specifically, you'd add an interval timer, so that after your preset number of minutes on, it would open the circuit and turn the defogger off. To restart the timer, you'd press the defogger button twice.

A possibly suitable timer relay can be found at McMaster-Carr, at the bottom of page 869. The DC-controlled versions of any of the relays listed under "DIN-Rail Mount Long-Life Relays with Multiple Timing Functions" would probably work. The price would be about US$50. I'd have to take a look at the wiring diagram in the service manual to be sure that it'd be as easy as I think it would.

eta: I found the datasheets for the pictured relays here and here.

Aaron T.

Hi arteitle - thanks for the links. Yes, the use of a solid state timer in line with the current dual position switch would probably achieve most of the desired effect. Depending on the circuit layout, this might (or might not) be able to cycle the built-in indicator light on & off to indicate when the timer is in operation.

I'm busy thinking about the intermittent rear wiper again so I may investigate the defogger in greater detail in a couple of months - thanks again.

My '06 Civic had a timed read window defroster... the button looks to be identical to the one in my Fit.