There is no bulb for this. There is a service bulletin though for the radio display being dark. If you will send me your VIN I will tell you if you are eligible for the repair under a warranty extension. This is assuming that this is an American Honda, not Canadian.
If eligible , your audio unit printed circuit board can be replaced by a dealer.
NOTE: Because of a class action settlement, the
warranty extension coverage for the audio unit display
on affected vehicles purchased or leased between
April 13, 2002, and November 7, 2006, is now 7 years
or 105,000 miles, whichever occurs first. For more
Extension: Vehicle Warranty Mileage.
In some audio units, a component failure on the PCB
(printed circuit board) could cause the audio display to
become dark or dim, and prevent the audio/HVAC
panel buttons from illuminating.
To ensure that customers have adequate warranty
coverage for this potential problem, American Honda is
increasing the warranty on the audio unit display to
7 years or 100,000 miles, whichever occurs first. For
other defects the standard 3 years or 36,000 miles
warranty applies, whichever occurs first.
NOTE: Affected vehicles do not have the navigation
Only a small number of vehicles within a wide range of
vehicles are affected by this warranty extension.
Before beginning work, verify vehicle eligibility by
checking at least one of these items:
2-Door LX V6 - ALL
2-Door EX and EX-L L4 Without Navigation - ALL
2-Door EX V6 Without Navigation - ALL
4-Door LX V6 - ALL
4-Door EX and EX-L L4 Without Navigation - ALL
4-Door EX V6 Without Navigation - ALL
2-Door EX L4 Without Navigation -
From VIN 1HGCM7...4A000001
2-Door EX and LX V6 Without Navigation -
From VIN 1HGCM8...4A000001
4-Door EX L4 Without Navigation -
From VIN 1HGCM5...4A000001
From VIN JHMCM5...4C000077
4-Door EX and LX V6 Without Navigation -
From VIN 1HGCM6...4A000001