How to Test if Your Limit Switch is Functional
In this short post, I am going to show you how to test if your magnetic limit switch sensor is functional. The steps work for switches from Aleko, Lockmaster and Viper gate openers. There are two types of limit switches, normally open (NO) and normally closed (NC). Aleko gate openers use Normally Close limit switch which will indicate a sticker stating NC you can see this on the top of your limit switch
Functionality check of these switches is quite easy and you just need a multi-meter and a limit magnet that is provided with your gate opener kit. There are three wires coming out from the switch; red, blue and white. White wire is common and other two are phase wires. So, you have to connect the white wire with the negative terminal of multi-meter (black wire) and other two wires with the positive terminal (red wire).
The multi-meter is to be set to continuity mode. Now, you observe the multi-meter reading. For a NO switches, it will read a finite voltage, generally 1.5 V and for a NC switch, it will read 0 V. Now, you take the permanent magnet close to the switch. If the switch is functional, the reading will reverse, that is for NO, the reading will become 0 V showing the switch is now closed and vice versa. If the limit is non-functional, you will see either fluctuation in voltage or no change. One important thing to keep in mind is that all limit switches are divided in the middle with some electronics. Thus, it has to be tested in two halves; top and bottom. If you don't take care of the divider, your results might be confusing.