| Also known as | 989R |
| Diagram | Fig. 18 — HEADLAMP, SPEEDOMETER, TACHOMETER · ref 16 |
| Subsystem | electrical |
| Listed in parts books | 1967–1974 |
Bulb (3W. M.C.C. 99-0548)
A 3-watt Lucas instrument/pilot bulb (989, later 989R) used in speedo, tach, and pilot-lamp positions across a range of British bike electrical assemblies.
This is the small pilot/instrument bulb that lights up the speedometer and tachometer faces, and shows up in warning-lamp and pilot-lamp positions across a wide run of headlamp and electrical-equipment figures in the parts books. Lucas number 989, also cataloged under 1505K52 and the later 989R form. It's a 3-watt bulb with the standard small bayonet base used for instrument and pilot lighting duties rather than the main headlamp bulb itself.
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Because it turns up in so many different figure titles - headlamp assemblies, wiring harness and switch groups, tail lamp sections, even ignition capacitor pages - it's clear this is one of those small parts fitted in more than one spot depending on the model and year of the bike. The catalog record doesn't pin it to one specific machine, so if you're chasing a burned-out pilot light or dash bulb, pull the old one and match the base and wattage before ordering.
Our records show this part was later superseded by 989R, so if your parts book lists 989R instead of 989, that's the same bulb under its updated number. Worth keeping a spare on hand since these are simple, easy items to lose track of in a junk drawer full of similar-looking bulbs.
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