stormin94

Actually, it should be maybe you're hot, and I'm not. I'm talking about the rear defroster. I've had the back part of my 4Runner taken apart quite a few times, and I've looked around where the defroster blower thing is, and I couldn't find a heating element, or anything. My question for you all is:

How the heck does the rear defroster work?

Does anyone know, or were the last written records about it burned in the library of Alexandria, so we have to start from scratch.

I push the switch, the light comes on, and I think there is air blowing over the back window, but it's cold, and I'm not even sure if there is air blowing over the window, it could just be a draft or something.

Any help?

ETRNL

if i understand it correctly it dosent blow air, it heats up the glass by heating small wires in the glass itself. it should only be 2 wires, somewhere..

stormin94

Mine doesn't have the grid of wires on the rear window, but it does have the defroster button. I've checked out a few other 4Runners, and they don't have a grid on the window either.

NwRunner

mine had little wires running through the glass, there was no air involved.

stormin94

Is this on a 2nd gen 4Runner, or a 3rd gen?

CyMoN

it means you do not have one if the window dose not have the wires on it

yotaman90

My 4runner has the wires on the glass, and it's a '94 also

eric-the-red

My 93, and all the 2nd gens, I've seen had the defroster wires. Of course up here in the Great White North things like that aren't optional. Either it was an option on yours or someone's replaced the window. I would think the only way to get rear defrost would be to put another window in, with the wires. Maybe you can find a used one.

sleaz22xx

Do you have defroster wires running thu the passenger side cargo area glass? I ask because if this is the case, my guess would be replacement glass from a PO(if there is a PO that is)?

My 94 sr5 has defrosters in both these locations

eric-the-red

The wires in the side glass aren't a defroster, it's an antenna. Supposed to help with radio reception, especially in the city when buildings block the signal.

ETRNL

i dont know if its optional or not but a way it tell if my windows are stock or not is that every window on my rig has the vin engraved in it. It is possible that it is a dealer option but i know that my rear window was a replacement because i war rear ended in the hatch and the window with defrost wires was 300 more it doesnt have the vin etched, i didnt pay for it the other persons insurance did cause he was at fault.

Noltz

That's not true with 2nd Gen 4Runners. Unsure about other models.

The wires in the back glass are the defroster. It does not use air. It's possible the glass has been replaced with one that does not have the wires (heating element). If there are no wires on your glass then there is no defrost.

I just repaired mine, so I'm sure about this. There's a single wire on each side of the gate running up to a tab on the glass itself. 12V+ is applied on one of these wires when you switch on the defrost BUTTON (not defrost lever on the HVAC controls). The other wire is a ground. Both must function in order for the defrost to work.

And to address ERTNL's note, VIN's are etched in at the dealership using 1-time-use papers. If you break a glass, you cannot get that number re-etched. When I was doing etching I would insert the 2 spare papers into the owners manual in case one broke. That way the owner could return and have the glass re-etched. It's the only way.

ETRNL

this too is true on mine as well its called a diversified fm antenna system.
then again mines a 3rd gen...
i wish i had got an owners manual with spare papers.

Noltz

Whoops! I completely missed "SIDE" in that post. Very sorry. Yes, the side glass antenna wires are just that.

leebee

hey noltz, get ready for some good natured jabs from the other toy techs on here! you might want to take that line and put it in your sig line:

Whoops! I completely missed "SIDE" in that post. Very sorry. Yes, the side glass antenna wires are just that.

nice to see another toy tech join the forum, can never have enough of them.

lee

stormin94

So I've got the wrong window. I don't have the wires, but I have the button, so I figured it was like the 1950's Pontiacs, with a little blower fan in the back window for a defroster. Well, similar anyway.

When I got my 4Runner, it was hit in the back, and the rear bumper/tailgate were replaced. I guess the donor vehicle didn't have that option.

This explains a lot. Thanks.

interrunner

so when i press my rear defroster button the light doesnt always come on. well most of the time the light doesnt come on. then when the light does come on it shuts off. and Im thinking the wires dont heat up when the light shuts off too. I think i have a bad relay or something? if it has a relay. any body else had the button fail before?

stormin94

It's possible, or it's hooked up wrong/one of the wires is frayed, or something. I think it has a timer to tell it when to shut off, and that could be bad, too.

I'm probably going to work on wiring mine up early next fall, since I won't really need a defroster going into the summer months. I've got the correct rear window now.