Hello Ronv
Not sure how to check if battery is tired to negative on buzzer but there is not continunity between them
Sorry no link as the information is not helpful
If i simply turn on one unit with the buzzer connected to the unit the buzzer sounds and stops ,when i turn off the unit the buzzer sounds getting quieter and stops
If i remove the buzzer and test voltage between postive and negative i get 10.81 on start up this reduces to 0.01 / 2 /3 volts and about the same when i turn off .It like a surge ?
Now when i test voltage between the negative of the buzzer wire being switch on / off and the negative of the buzzer wire from another parking unit on but not detecting i get
turn on -0.16
turn off 10 volts
turn on 3 volts
As these wires would normally go to a buzzer they seem to be used for power on and off as well as sounding when under detection
So im thinking of just putting a blocking diode on each negative to block the current with a resistor ,i have tried this and it works
have also wired the negative side of a buzzer to negative side of buzzer wire and the postive side without diode. now when testing across both negatives the voltage is blocked
When i connect this to source it all works buzzer works and when i power on / off power makes sound and stops, and sounds when detecting How i dont know
When i now test voltage negative wire going to source and the buzzer negative wire but its buzzer`s positive side i get a live voltage at source and negative at the positive side .
My only concern now is if i just use a blocking diode would i need a resistor to dissapate the voltage
Thanks Tony got there at last