Take this 4 pin NC relay as an example; you can test a relay with a multimeter in the following steps:

1. Turn off any power load to the relay

2. Set the multimeter to 2KΩ resistance mode

3. Attach the probes with two coil contacts of the relay

A standard 12V relay has a coil resistance of around 50~200 ohms.

4. Switch the multimeter to continuity mode (some DMM integrates it with the diode mode)

5. Connect the probes with both the COM contact (30) and the NO contact (87)

6. Supply an independent power source to the coil terminations according to the relay ratings

7. Keep the relay mounted with power and connect the meter probes with two switch contacts again.

(Originally posted on Easybom, Click to Read more)