Battery drain defog switch on all the time, defog not working seems to be draining battery

Fuse box rear , fuse #23 30 amp ! Do you know where this is located ? There is also a relay for the Rear window defogger , located in the same rear fuse box .
Fuse Block - Rear
Left side of the luggage compartment, behind the left rear wheel well . But you really need to know how it works , you can check fuse an relay .
Rear Window Defogger Operation
Battery positive voltage is supplied through the BATT 1 fuse in the underhood fuse block to the rear defog relay switched input. When the rear defog switch button is pressed, the body control module (BCM) energizes the rear defog relay by providing a B+ to the control circuit of the rear defog relay. This allows battery positive voltage from the relay switched input through the switch contacts and out the relay switched output to the rear window defogger grid. The HVAC control module houses the rear defog switch and also illuminates the rear defog indicator on the switch button, upon this request. Ground for the rear window defogger grid is provided by G301 for the Sedan or G302 For the Extended Sedan.

Rear Window Defogger System Components
The rear window defogger system consist of the following components:
• HVAC control module
• Body control module (BCM)
• DEFOG relay
• Rear window defogger grid
Rear Window Defogger Operation
When you turn the ignition to the ON position, ignition voltage is supplied to the DEFOG relay coil. Battery positive voltage is supplied at all times to the DEFOG relay switched input. When the rear window defogger switch is depressed, the HVAC control module illuminates the rear window defogger indicator and sends a class 2 message to the BCM. The BCM energizes the DEFOG relay by grounding the control circuit of the relay. This allows battery positive voltage from the relay switched input through the switch contacts and out the relay switched output to the rear window defogger. Ground for the rear window defogger is provided by G306 or G390 (crew cab).
When you turn ON the ignition and press the rear window defogger switch for the first time, the defogger cycle lasts 10 minutes. Further operation results in 5 minute defogger cycles.

Do you know what your messing with ? What's the problem ?

You need to disconnect the battery negative lead and place an ammeter between battery and lead, note the current draw with every thing switched off, then start removing one fuse at a time from fuse box and see if ammeter drops significantly if not refit fuse and remove the next one and repeat this until you find the one that causes a significant drop, then you will have found the circuit that is draining the battery, you need to check this circuit to find cause of power draw and repair as required, let me know how you get on

Switch, fuse or maybe the wiring to the window has come loose or off, happens alot, kits are available at local auto parts stores...
I hope that helps...

Look at the light switch. Sometimes it will turn on the headlites by itself and drain the battery.

The switch itself is probably bad. You can pop the switch out and unplug the wires to verify. You can pull the fuse to deactivate temporarily. The fuse is probably powering other items too, so find out what else is sharing the fuse.

The two circuits are separate other than the multi-function switch in the column. So its possible the turn signal switch has failed. And it could be shorted out to the point of draining the battery.
I would unplug the switch and check to see if the voltage drain has stopped.

when u shut the car off use a volt tester and test the battery your looking for any drain on the battery or the batter may not be able to hold a charge anymore.

Can't help with the 4x4,sorry.Fully charge battery hook up pos. wire.Then touch grd wire like you want to arc it.Watch close to see spark.If you see one then go to fuses. Pull one then check for arc if still arcs try another fuse,etc.till you don,t see arc.What's the fuse for? that's your culprit.Power drainers are horn circuits,brake lite switch,radios that should go off with ignition.Does that 4x4 switch work with key off?That could be drain if it stays on when you think it's off?

good luck worked on these for years, trey replacing the battery isolaters.