mountainbrew

Hi guys! Pretty new to the classic 4RUNNER thing. 1986 22re standard.
When I bought the truck it had a standard rear window, and I swapped it out for one with a rear defrost grid.
My problem questions are...
1) what wires are the pos and neg for the grid? Are they part of the big cluster that runs into the tail gate?
2) what fuse controls the rear defogger? I think my fuse panel on my drivers side kick panel may be a swap out. It's four columns across and three rows down, with the left most row totally empty.

Sorry if this is FNG question, I just could find anything about the path of the wiring for the rear defogger

wyoming9

iTrader: (1)

Does your 4Runner have the switch and relay for the defroster .

It also is tied into the back window limit switch so it will not turn on with the window down

.the fuse is a 20 amp fuse positive is red and your ground is black it grounds in the hatch some place on the left side.

If the wires are in the harness they come into the hatch with the main harness

mountainbrew

So I replaced the appropriate fuse and got the switch to activate. When it did, I could hear/ feel a click from this switch located in the wall behind the driver. As you can see there are four black and one orange wire coming out of the relay. I assume they are +/- in, +/- out, and the switch signal. They feed back into the main cluster, but the are not in the group when it goes into the hatch. Before I start ripping the wiring harness apart, am I even looking at the correct stuff?

wyoming9

iTrader: (1)

Yes that is the relay.

But your a little off on your relay operation .

you always have a coil to pull in the contacts or pull them apart in this case just one set that is normally open.

pins 1 and 3 are the coil pins 2 and 4 are the contacts

Before you go to all this trouble you did check the defroster grid is not open in several places as likes to happen when they get old.

If you plan to keep this vehicle you should look for a copy of Toyota`s Electrical wiring diagrams makes these things so much easier.

AdmiralYoda

The most common point of failure is where the wires connect to the window itself. Grease/Grime and old connectors will not produce the best connection.

Like you I recently replaced my rear window as my old one was scratched to hell. Well I actually replaced the whole tailgate including the harness! My rear window defrost does not work either and I can hear the relay contacts working. When I get some spare time I'll play with my multi-meter and check the connections on the back window.

LITLRED

I spent quite a bit of time troubleshooting the defroster and came to the conclusion that the 28 year old grid was broken in half a dozen places at least.
The window actually got warm but only the bottom 1/2 inch or so.
I would like to buy a new replacement but had no luck searching for one.
Anyone know of a source?

RAD4Runner

Schematic if it would help....

mountainbrew

Thanks guys! So good news, I found the line and threw the multimeter on it... 12v! However the line stops at the final harness adapter right before the cluster goes into the trunk. So now I am just going to jimmy rig some wire to test if the defroster grid is complete and uninterrupted. Anyone know of a good way to do that, I mean, besides waiting for the first hard frost.....

mountainbrew

Nevermind...