Yes, a bad relay can still click, and the clicking sound is often a mechanical indication that the relay is attempting to operate. The clicking noise is typically produced by the movement of the relay's internal switch mechanism when the coil is energized.
However, the fact that a relay clicks does not necessarily mean that it is functioning correctly in terms of controlling the electrical circuit it is meant to manage. A relay can click but fail to properly switch the load or exhibit other issues due to internal electrical or mechanical faults. Here are a few reasons why a relay might click but still be considered "bad":
Internal Contacts Failure: The contacts inside the relay may be worn out, corroded, or otherwise damaged, preventing proper electrical continuity.
Coil Issues: While the relay may produce the clicking sound, the coil might not be generating enough magnetic force to close the contacts effectively.
Sticking Contacts: The relay contacts may stick in the closed or open position, preventing proper operation.
Overheating Damage: Over time, relays can overheat due to high current loads or poor connections, leading to internal damage that affects their performance.
Mechanical Failure: Mechanical parts within the relay, such as springs or the armature, can fail, hindering the relay's ability to switch effectively.
If you suspect a relay is bad, it's crucial to perform a comprehensive testing procedure, including electrical and functional tests, to assess its overall functionality. This may involve using a multimeter to measure resistance, checking for continuity, and applying the appropriate voltage to the coil to observe its behavior. If the relay is controlling a specific component in your car (such as a fan, fuel pump, or headlights), testing the functionality of that component can also provide additional information.
In automotive troubleshooting, if you encounter a clicking sound but the associated component is not operating, it's a good indicator that further investigation and testing of the relay and related circuits are needed.