It is easy to tell a starter solenoid is going bad because the engine makes no noise when turning the key in the ignition. The solenoid is a device that charges and directs current through the starter, meaning a lack of response requires replacing that part. The solenoid is mostly present only in Ford vehicles.
The starter solenoid directs power through the engine and helps reinforce the charge in a starter component. Insufficient flow of electricity results in a lack of response from the engine, causing no sound or response when users try to start a car or truck. As the solenoid goes bad, drivers notice that there is an increasing reluctance from the engine to turn over. Subsequent tries show the car or truck makes a loud clunking or banging noise but does not start.
The solenoid is a mounted above the starter in a car and pulls charge from the device as energy is channeled through it. A bad starter solenoid does not hold or feed the charge back into a starter and does not allow the engine to run. This also happens when the grounding component of a solenoid is insufficient, causing too much charge to pool in the device and making it unsafe to allow power to continue to flow.