Removed my old burned out fog light switch.
I wanted to check my new fog lights before replacing the switch.
Long story short I checked the wire harness that goes to switch for volts dc.
Number 3 (on the pciture above) the power into the switch had no voltage.
Tested with headlight and ingintion on / high beam off.

So what supplies the voltage into the fog light switch?
Where does it come from fuses ect...?

I found tons of info about what's supplies voltage to the fog lights after the switch but nothing about where the power comes from going into the switch.

 

It would help to know what year XJ this is.

 

My bad it's a 97

 

Well, check the fuse for the lights. If that's good then check the relays. Your manual has the diagram for which ones to check.

 

97 PDC (relay), Fog Lamps fuse F24:

 

97 Fog Lamps circuit:

 

I actually think I figured it out but thanks gents.
It seems fuse number 6 controls the power into the switchs and it blown so that's probably my problem.

 

97 JB. Fog Lamps relay control coil fuse F7:

 

Please post your year in the CP area so all will know without you posting it every time, very useful for others to help you.

 

What he said. You can swap in a relay from one of the other spots to see if it's the relay.