Quote Originally Posted by radargeek View Post
How are you measuring it? If you measure it relative to ground, it'll always be zero volts. You should connect the + lead of your voltmeter to a 12V source and the - lead to the mute wire. Then the meter should read 12V when the ground (mute) is active and 0V if it isn't.

It should active when alerting (jamming).
I made a continuity test : negative lead of the voltmeter to chassis and the positive lead to the blue\green : circuit is closed.
When i was doing the same test with the Li , the circuit was open under no alert and closed under alert with the Osprey.

I have no way to trigger an alert , no tester no gun

I will test your way '' + lead of your voltmeter to a 12V source and the - lead to the mute wire.
Then the meter should read 12V when the ground (mute) is active and 0V if it isn't.''