After rereading your post I should say that I dont think your radio problems are caused by your GEM. Chances are the problem is in the radio unit itself. The other problems could easily be the GEM or fuse box though.
The GEM is attached to the back of the fuse box or as the manual calls it the "instrument fuse junction panel". I guess "fuse box" was too easy
Look carefully above the fuse box for any signs of water that has dripped down....stains, clean lines in the dust etc.
I've never had any luck drying out fuse boxes but some people have.
As for what manuals are good.....some people here highly recommend Haynes manuals but I always use genuine Ford ones.
Apparently the Ford cds and dvds can be found easily on Ebay and sell for not too much money. The Ford cds usually cover only one year of either car or truck while the dvds covers many years of all lines.
Also take a look at
motorhaven.autoanything.com and see if you can find a manual for your truck there.
A site with some online manuals that isnt too bad is
As for what the GEM controls here is what the manual says....
GEM Features and Functions
The GEM controls the following features:
Wipers/washers (front/rear).
Warning chimes.
Battery saver.
Illuminated entry and courtesy lamps.
Driver power window.
Accessory delay.
4-Wheel drive.
I cant post the pictures from the manual here but the instructions for replacing the GEM/fuse box are.........
--------------------------------------------------------------------------------
Generic Electronic Module (GEM)
Removal
Disconnect the battery ground cable (14301).
Remove the cover from the instrument panel fuse junction panel.
NOTE: On vehicles equipped with automatic transmissions, move the shift lever to the 1 position to ease removal.
Carefully press the (A) clips and remove the (B) steering column opening cover.
Postion the hood latch release handle aside.
Remove the screws.
Position the hood latch release aside.
Position the parking brake release handle aside.
Remove the screws.
Position the parking brake release handle aside.
Remove the lower instrument panel steering column cover (044F08).
Remove the six lower instrument panel steering column cover bolts.
Remove the lower instrument panel steering column cover.
Remove the two (A) bulkhead electrical connectors from the (B) instrument panel fuse junction panel.
Remove the two (A) instrument panel fuse junction panel bolts and remove the two (B) interior fuse junction panel nuts.
Disconnect the three (A) GEM/CTM electrical connectors from the (B) GEM/CTM.
Remove the three GEM/CTM screws and the GEM/CTM.
Installation
NOTE: When the battery (10655) is disconnected and reconnected, some abnormal drive symptoms may occur while the vehicle relearns its adaptive strategy. The vehicle may need to be driven 16 km (10 mi) or more to relearn the strategy.
To install, reverse the removal procedure.
Check for proper operation.
Install the lower instrument panel steering column cover.
Position the lower instrument panel steering column cover.
Install the six bolts.
Install the parking brake release handle.
Position the parking brake release handle.
Install the screws.
Install the hood latch release handle.
Position the hood latch release handle.
Install the screws.
NOTE: On vehicles equipped with automatic transmissions, move the shift lever to the 1 position to ease installation.
Carefully press the (A) clips and install the (B) steering column opening cover.