On Tuesday, June 7, 2016 at 12:46:08 PM UTC-4, wrote:
Hella horn for an intermittent alarm.

which pin is ground ?

how tell ?

is either pin grnd-pwr ?

https://photos.google.com/photo/AF1Q...Wf7oZ1B-iTQkit

If the contacts (Usually push-on make connectors) are both isolated from the body of the horn, it makes no difference which one is "hot" and which one is "ground". But, use a VOM to check each terminal for continuity to the mounting studs - and if there is continuity, that one will be the Ground.

Pretty basic if this is for an automotive application where the frame often serves as a common ground. But, again, these days, alarm systems try to isolate key components and provide separate grounds so that they are less easily defeated.

Peter Wieck
Melrose Park, PA