I have a 2000 ford Ranger XLT with the 4.0. Fuse 6 blows immediately. 6 powers 4x4 and reverse lamps.

 

Welcome to the foum

Manual or automatic?

And is it a 4x4?

Remove fuse 6 and with Key on test which slot for the fuse has 12volts, thats the power side, the OTHER slot is the Load side, the side with the short that blows the fuse
Turn off the key

Test that Load slot with OHM meter to any Ground, should be above 10 ohms, below that is a short

Fuse 6 powers a few things, its not the 4x4 system its just the Vacuum solenoid for the front hubs, so try unplugging it(on passenger side frame rail under engine area), has 2 vacuum hoses and 3 wire connector
After unplugging Vacuum solenoid test fuse 6 load slot again, if ohms are up then that solenoid is bad leave it unplugged

If ohms don't change then plug it back in

If automatic trans fuse 6 also powers OD on/off Button, and these are known to short where wire comes out of shifter arm in steering column
You need to remove clamshell on steering column to unplug this one, but needs to be done
Unplug it and test OHMs

Yes, it powers backup lights but also Daytime driving lights(DRL)

If automatic, there will be a DTR switch on drivers side of transmission, its on the shift linkage, unplug it and test OHMs to see if they go high

If you have a DRL module then you will need to find it and unplug it, not sure where it is in 2000 Ranger, and see if OHMs go high

 

Thanks for the reply! I'll try that this weekend. Its a 4x4 also.