I have a 12v low trigger relay module (like this one on ebay ) that is working correctly in an alarm panel. Aux input on the alarm board activates to ground and the relay operates. I currently bridge the ground and trigger pins so the aux input both powers and triggers the relay module. If I remove the wire bridge so the relay module is just powered (but not triggered) and use my multi meter (as ohm meter) to bridge the ground and trigger together, the relay activates. The datasheet says 5ma trigger current but a multi meter resistance is in Mohms isn't it? How could enough current flow? The aim is to use an Arduino low output to also activate the relay but even though I show Mohms between the output and ground, the relay instantly activates. I've tried two different multi meters. Thanks for any insight.