Re: Third Brake Light (CHMSL) Problem
Looking at the scat, two possibilities jump out at me. the first, if the 510 Ohm resistor is open, the bulbs would fry immediately, and if it were shorted you'd blow a fuse. After re-reading your post, however, you're not getting power to the lamp assembly, so the theory about the resistor being open is shot, but it could still be shorted and you just haven't located the fuse.
the other possibility is the High Mounted Stoplamp Relay. If it's shot, the power will never get sent up the line to the lamp, however I can't help you on where it's physically located.
If the stop switch were bad, you'd get no break lights at all, so that eliminates the brake pedal.
I don't think the cruise control would affect this, but if you even have CC, does it work? If the cruise circuitry were a dead short to ground, the CHMSL wouldn't work, but then again, you'd blow that 10A fuse... If CC works, the problem is isolated to the CHMSL circuit which leaves you with the relay or a malfunction inside the multifunction switch.
(elctronics technician, US Navy)
(Sold) '98 S-10 4.3L Ext. Cab 2WD, Red
Mods: New Paper Air filter, Bosch O2 Sensors, NGK TR55 plugs, Duralast Lifetime gaurantee front brake pads, Duralast wires, cap and rotor, new driver side mirror, shaved seat recline lever, 2-piece grill
Real mods: Bilstein shocks, Moog 5664 Coils, Dueler A/T 235/75R15, my own version of the airbox mod