This multi-voltage glow plug tester from Sykes Pickavant works on all types of glow plugs and indeed, at any voltage. It displays open and short circuit an also measures actual glow plug resistance for testing the plug specification.
The unit has a 9V internal battery and warns you when it’s running low on juice.
Danger, high voltage!
Click to enlarge25 Aug 2011
Glow plug tester from Sykes Pickavant