Either ignition switch or IVR (instrument voltage regulator) on the back of the cluster, or the 8 ohm resistance wire from the ig sw to the cluster has burned up, or bad connection at cluster connector.
Pull cluster, and check for voltage at the GY/Y wire at terminal 48 on cluster connector with key turned to RUN. Using a DMM should net battery voltage. If that checks out, use a test light that draws around an amp between GY/Y and ground. Light should light, but be pretty dim. How dim depends on the exact amp draw of the bulb. If that checks out, the IVR could be bad. Replacement IVRs are around $35, or you can build a solid state one that will last forever following the tech article on this site. Could also just be a bad connection at the cluster connector. Taking the connectors out of the cluster, cleaning the contacts, and reinstalling them may clear up the problem.
BTW, As Ryan said, welcome to the board!
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Jeff Korn
88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 23 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 04 Taurus Duratec (wifes car) // 91 Topaz (daughters first car)
Jeff Korn
88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
11 Crown Vic Interceptor
14 Toyota Camry (wifes car)
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3