While it might sound like a bit of extraterrestrial tech, a starter solenoid is a common component of modern vehicle ignition systems. Starter solenoids are reliable, often lasting 100,000-150,000 miles before showing any troublesome symptoms.
How do you know if your starter solenoid is bad? If the engine struggles during startup or doesn’t crank at all, the solenoid may be going defective/have failed.
Pay attention to clicking sounds while turning the key or continuous grinding/whining after the engine starts, which might suggest issues with the starter solenoid.
Below, we’ll explore the symptoms of a defective starter solenoid in greater detail. But first, let’s look at how the starter solenoid works and where to find it.
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What Is A Starter Solenoid, And How Does It Work?
Simply put, a car’s starting solenoid is a device that relays power from the battery to the starter motor. For more information on the exact process, read on. Otherwise, skip to the next section to learn where the solenoid is located.
Inside a solenoid is an iron piston that can move forward and backward. The piston has copper wire wound around one end and a coil on the other.
As electricity from the battery flows through the solenoid’s copper wiring, it becomes activated, creating an electromagnetic field that attracts the metal piston and pulls it back. This also compresses the spring, which returns the piston to its original position once the solenoid de-energizes.
With the piston pulled back, an electrical circuit is closed that allows power to reach the starter motor and, in turn, rotate the flywheel that cranks the engine. Once the engine starts, the circuit opens again, the piston returns, and electricity ceases flowing.
Want to see a visual illustration? Don’t forget to watch the video below from TecknoMechanics:
Where Is The Starter Solenoid Located?
The starter solenoid is cylindrical shaped and is often attached to or incorporated into the starter motor. The motor’s location varies between models, and you may need a flashlight, but it’s usually under the transmission or under the exhaust or intake manifold.
You can also follow the battery’s positive terminal to the starter solenoid, though, depending on the vehicle, you may need to remove the battery and platform to access it.
Look for a couple of electrical connection points coming out of the back of the solenoid. One leads to the battery’s positive terminal and another to the starter motor. A third tiny point connects to the ignition cylinder and communicates when the key is being rotated.
5 Signs Of A Bad Starter Solenoid
What causes a starter solenoid to go bad? General wear and tear associated with age is the primary cause of a faulty solenoid. This includes extended exposure to the heat created by the motor (and/or extreme climates), moisture entering the engine bay, or worn, corroded wiring.
Parking in a garage and giving the engine a rest during prolonged drives can help reduce potential heat damage. To minimize water intrusion and protect against electrical shorts and corrosion, be sure to keep the vehicle’s drainage lines clear of obstruction and avoid driving through enormous puddles.
Simple upkeep hacks like these are great for extending the life of a vehicle. Be sure to check out our previous article for more car maintenance tips.
1. Rapid Clicking When Turning Ignition Key
If turning the ignition key results in rapid clicking sounds, the starter solenoid may not be getting enough electrical current to turn the flywheel and engage the spinning crankshaft.
Before replacing the solenoid, though, be sure to have it examined (or check it yourself with a multimeter), as a defective battery can cause similar symptoms.
2. Starter Motor Stays On After Engine Starts
A starter motor makes a distinct grinding/whining noise when cranking an engine over, but only for a moment. Once the engine is running, the starter should shut off. But, if the solenoid has failed, the starter may continue spinning.
Not addressing this issue may result in the starter itself requiring replacement, which is more costly than just the solenoid.
3. Nothing Happens When Attempting Startup
Cars typically click when you turn the ignition key, and starters make a loud noise. However, if nothing happens, the solenoid may be the culprit.
Pay close attention to the electronics inside the vehicle. If the radio and lights turn on, as normal, the solenoid is likely at fault. But if nothing works or functions, the issue may stem from a dead battery.
4. Starter Motor Cranks But Engine Does Not
You may need a new solenoid if you hear the starter motor spin but the engine doesn’t attempt to turn over. This typically occurs for the same reason as other indicators on this list; the starter isn’t receiving sufficient power to rotate the crankshaft.
Testing the solenoid will tell you if you need a fresh one, but you may find the starter itself is the issue or that you need to replace the battery.
5. Engine Starts Only Some Of The Time
Another sign of a starter solenoid that’s beginning to go bad is the engine only starting intermittently. This indicates the solenoid is on its final legs and may fail soon entirely. You may also notice some of the other faulty solenoid symptoms on this list.
Think Your Starter Solenoid Is Bad? Here’s What To Do
If you think your starter solenoid is defective, the first step is to test it, as there are numerous reasons a car might not start. You can either take your car to a shop for a fee or use a multimeter to test it at home.
Not sure how to inspect a starter solenoid? Check out the below YouTube video from TutoBuild Eng for a step-by-step visual explanation:
Should the starter solenoid be at fault, you can either take it to a mechanic or, if you’re quite skilled with an engine, swap it out yourself.
The solenoid’s precise location differs between models, but the below video from Thinking Outside Box does a good job of explaining the basics:
What happens if you ignore a defective starter solenoid? Eventually, you won’t be able to start your car. Instead of leaving it up to chance, be sure to test the starter solenoid as soon as symptoms appear.
