The bulb is the least likely reason, but possible. Even so, if you work by "process of elimination" starting with the easiest, the bulb is not your first try.

Do this: Remove the D+ wire connector from the alternator, and ground it. Not to the alternator housing, which is isolated on its rubber bushings, but to a known good ground like the studs protruding from the shock tower. Then turn on the key to the run position. The light(s) should come on. If not, then you can pursue a fix in the instrument cluster, or, as some have found, at the gray plug on the firewall.
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Art Benstein near Baltimore

Don't be irreplaceable. If you can't be replaced, you can't be promoted.