What Are the Symptoms of a Faulty Solenoid Switch?
3 Answers
When the ignition switch is turned to the start position, the solenoid switch shows no response. Possible causes include an open circuit in the pull-in coil, an open circuit in the hold-in coil, burnt contact disc, or insufficient contact thickness. More details are as follows: 1. Under normal circumstances, when the ignition switch is turned to the start position, a "click" sound should be heard from the solenoid switch, indicating that the drive gear engages with the flywheel ring gear. If this does not occur, it indicates a solenoid switch malfunction. Remove and disassemble the solenoid switch for inspection. If the pull-in coil or hold-in coil connections are broken, solder them firmly with a soldering iron. If a soldering iron is not available, clean the ground terminal of the hold-in coil and press it into the solenoid switch cover, then tighten the cover screws. If the above conditions are normal, check if the contact disc is severely burnt. If so, polish it with fine sandpaper or flip it for use. If the contact thickness is less than the minimum requirement (e.g., below millimeters) or severely burnt, replace it. 2. The working principle of the solenoid switch is that when the coil is energized, it generates electromagnetic force, moving the plunger. This action, on one hand, pulls the drive mechanism to engage the starter pinion with the engine flywheel ring gear, and on the other hand, pushes the switch contacts to close, energizing the DC motor to start the engine.
Last time my car wouldn't start, it had this exact problem. When turning the key, there was no response at all, but the dashboard lights were still on, indicating it wasn't a battery issue. If you listen carefully under the hood, you can hear strange clicking or clunking sounds, especially noticeable when the engine is cold in the morning. Once after starting, the starter motor kept spinning freely, making a harsh whirring noise. If the car suddenly stalls while driving and you find the starter can't engage with the engine when trying to restart, it means the part in the solenoid that pushes the gear is stuck. This situation shouldn't be delayed - I once tried starting multiple times and ended up blowing the ignition switch fuse.
From an electrical circuit perspective, the solenoid switch acts like the master valve of the starting system. The typical symptom of its failure is the complete absence of the engaging "click" sound when turning the key to the start position—you won't hear that mechanical snap. If the internal contacts of the solenoid are burnt out, you might hear the engaging sound but the starter motor won't turn at all, and the voltmeter on the dashboard will suddenly drop. More subtle is the case of poor contact, where it might take seven or eight attempts before the engine starts successfully once. Problems are more common during the rainy season, as moisture can reduce the solenoid's magnetic pull, causing the car to make a tractor-like rattling sound.
