Before we get into the symptoms of a bad starter solenoid, let’s discuss what this part does and how it works.

Although you may have heard of a starter solenoid, you might not know what the part actually does. Basically, the starter solenoid is an electromechanical device that engages the starter motor. Most starter solenoids are mounted directly on top of the starter.

When you start your car, electrical current from the battery travels through the starting circuit (relay, etc.) to the starter solenoid. When energized, a set of windings inside the solenoid force a plunger and shift fork to engage the starter motor’s drive assembly.

At the same time, the plunger pushes a disc against a set of contacts, allowing current to flow through the solenoid to the starter. As a result, the starter drive assembly cranks the engine to get it going.

After reading the description above, you can probably surmise that a faulty starter solenoid can prevent the starter from operating. And that can keep your car’s engine from starting.

As a result, the common signs of a bad starter solenoid include:

Engine Doesn’t Crank or Start

When the starter solenoid decides to call it quits, the starter motor won’t work, either. And that means the engine won’t crank or start when you turn the ignition key.

No Clicking Noise When Trying to Start the Engine

That clicking noise you hear when you go to start your car (but nothing happens) is either the starter solenoid or the starter relay. So, if you don’t hear anything—not even a click—when trying to start your car, you may be dealing with a bad starter solenoid.

Starter Spins Without Fully Engaging the Flywheel (Rare)

Although rare, a weak solenoid can allow the starter to spin without engaging the engine’s flywheel or flexplate. In such a scenario, you’ll hear the starter spinning, but the engine won’t crank.

Engine Cranks Slowly (Rare)

It’s possible for high resistance in the starter solenoid to cause the contacts to burn. As a result, there will be excessive resistance in the starter motor, potentially resulting in an engine that cranks slowly. Once again, this scenario is rather uncommon.

Common Problems That Can Mimic a Bad Starter Solenoid

Several problems can mimic a bad starter solenoid or starter motor. The most common include:

• Dead battery
• Loose or corroded battery terminals/cables
• Issues with the starting circuit
• Seized engine

How to Tell if a Starter Solenoid is Bad

Testing a starter solenoid is usually fairly straightforward. The diagnostic procedure is mostly a process of elimination.

Test the battery

Whenever an engine doesn’t crank (or it sluggishly tries to turn over), you want to begin your troubleshooting process at the battery. You can find out how to test a battery by reading this article: How to Test a Car Battery With a Multimeter.

Check That Power is Getting to the Starter Solenoid

Once you know that the battery is good, you’ll want to check whether power is getting to the starter solenoid. If there’s an issue somewhere in the starting circuit, power won’t reach the solenoid, resulting in a vehicle that doesn’t crank or start.

Test the Starter Solenoid Itself

If you find that power is indeed getting to the starter solenoid, the next step is to test the solenoid itself.

Many repair manuals recommend checking the starter solenoid for internal continuity if the vehicle doesn’t crank. To perform this test, you’ll need a digital multimeter (DMM). Here’s how it’s done:

• Put on your safety glasses.
• Make sure the vehicle’s ignition switch is turned to the OFF position.
• Set your digital multimeter (DMM) to the ohms setting.
• Disconnect the starter cable from the solenoid’s ‘M’ terminal (the terminal that attaches to the cable going to the starter motor).
• Connect one meter lead to the solenoid’s ‘S’ terminal (the terminal that receives power from the ignition switch).
• Connect the other meter lead to the solenoid’s ‘M’ terminal.
• If your meter reads out of limits (OL), the solenoid is faulty and should be replaced.

• Next, connect one meter lead to the solenoid’s ‘S’ terminal.
• Connect the other meter lead to ground on the starter motor’s case.
• If your meter reads out of limits (OL), the solenoid is faulty and should be replaced.

You can also bench test both the starter solenoid and the starter motor.