the magnet is about 5 ohms. There is no diode. It measures the same when changing polarity. When back probing the connector with the magnet connected I get 0 volts. When I unplug it it jumps to 11.49v. I checked the gap again. 15'''. I smacked it with a small dead blow hammer to see if it would engage but it did not. Not surprising with 0v on the magnet.Is this with the magnet plugged in? I use push pins to backprobe the connector. If the magnet isn't plugged in when taking a voltage reading any high resistance connection will not be found. (Reads good voltage unplugged with no current: plug it in and voltage drops like a rock to near 0 with a high resistance connection.)
An ohm test of the magnet will also answer questions. Keep in mind to measure it both ways as there may be a diode built in to the magnet.