bulb voltage for M813 pre-heater/glow plug indicator

[US6x4]

It looks like oshkosh equipment lists this bulb as 6 volt and others don't mention a voltage. Needless to say the 2.5 volt bulb that came with my truck was fried. What is the correct voltage? 24v?

 

[162tcat]

A 24 volt bulb will work no matter what, just may be dim. Check the TM for part number or nsn


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[Scar59]

The stock intake heater on the 813 is 12 volts .hence the power lead in on one battery. - the bulb is 12 volts also.

 

[US6x4]

It looks like the NSN # is 6240-00-012-5588

 

[US6x4]

The NSN posted above correlates to a size 55 miniature automotive bulb which is rated for 7 volts. I put a multi-meter in the socket and got steady readings between 6.7-7.1 volts.
This bulb socket had power to it regardless of the battery ON/OFF switch position so you wouldn't want to leave the pre-heater switch on.