To test a relay coil when it is out of the circuit, what should you measure?

When testing a relay coil that is out of the circuit, measuring resistance is the ideal choice. This method allows you to determine whether the coil has an open circuit (indicating a broken wire or an open coil) or if it has a short circuit (which may cause it to be inoperative).

When you measure the resistance of the coil, you will obtain a specific value that corresponds to the rated resistance of the coil. If the resistance is significantly higher than expected or infinite, it indicates that the coil is faulty. If the resistance is close to zero, it suggests a short, which is also a problem.

Measuring current or voltage while connected to the circuit is not effective because the conditions of the circuit could influence the readings, potentially leading to misleading conclusions. Capacitance is not relevant for testing a relay coil, as it does not provide a measure of functionality in this context.