How to Test a Starter Motor | Quick Guide + Honda L13A Example

A faulty starter motor can leave you stranded with a no-start situation, making it one of the most frustrating automotive issues. Common symptoms of a failing starter include clicking sounds when you turn the key, slow or labored cranking, or the engine not turning over at all. In some cases, you might notice intermittent starting problems, where the engine starts fine one day but refuses the next. Other warning signs include smoke or burning smells coming from the starter area or the dash lights dimming when you try to crank the engine.

Starter motors are subject to wear and tear over time, especially in older vehicles or those exposed to extreme conditions. Worn-out brushes and bearings inside the motor can cause it to spin weakly or seize up completely. A faulty solenoidmight prevent the starter gear from engaging the flywheel, resulting in no crank. Other culprits include corroded or loose terminals, bad internal wiring, or overheating that damages the motor windings. Sometimes, external factors like a weak battery or poor ground connection can mimic starter failure, making a proper bench test essential.

In the video below, you’ll see a Honda L13A starter motor undergoing a simple bench test to demonstrate what a healthy starter should look and sound like. While this isn’t a step-by-step tutorial, it provides a clear example of how a properly functioning unit operates when connected directly to a battery. After watching, continue reading for a detailed breakdown of the general steps to test any starter motor safely and effectively.

Steps to Test a Starter Motor (Bench Test):

1. Safety First

• Wear gloves and safety glasses.
• Work in a well-ventilated space, and secure the starter motor firmly on a bench or vise.

2. Inspect the Starter Visually

• Check for obvious damage, like cracked housing, corroded terminals, burnt smell, or loose/missing bolts.

3. Identify the Terminals

• Battery terminal (B+): Large terminal connected to the battery’s positive.
• Solenoid terminal (S or trigger terminal): Small terminal for the ignition switch signal.
• Ground: The starter body itself is usually the ground.

4. Set Up the Battery & Jumper Wires

• Use a fully charged 12V battery and a pair of heavy-duty jumper cables.
• Connect the starter housing to the battery negative (-) terminal (this grounds the unit).

5. Bench Test the Motor (Direct Power Test)

• Briefly touch the positive jumper cable to the battery terminal (B+) on the starter.
• If the motor spins but the gear doesn’t pop out, the motor works but the solenoid might be faulty.

6. Bench Test the Solenoid (Full Engagement Test)

• Connect the positive jumper cable to the B+ terminal.
• Use a jumper wire or screwdriver to bridge between the B+ terminal and the solenoid trigger terminal (S).
• The solenoid should click, and the starter gear (Bendix gear) should extend and spin.
  • No spin + no click: Faulty solenoid or bad internal motor.
  • Click but no spin: Likely motor issue.
  • Spin but no gear extension: Solenoid plunger issue.

7. Listen and Observe

• A healthy starter should spin strong and fast with no grinding, hesitation, or weak engagement.

8. Optional: Voltage Drop Test

• While engaging the starter, use a multimeter to check for voltage drop across terminals to diagnose bad wiring or internal resistance.

Helpful Notes:

• Always use a fully charged battery for testing to avoid false results.
• If the motor spins but the gear doesn’t pop out, the solenoid may be defective.
• For surplus starters, a bench test is crucial before installation.
• Avoid long test runs to prevent overheating the starter.

Testing a starter motor before installation is a crucial step, especially when dealing with surplus or secondhand parts. A simple bench test can help you avoid unnecessary troubleshooting later and ensure that the starter is ready to perform under load. While this guide provides a general method for most starters, always consult your specific vehicle’s manual for any model-specific procedures. If you’re not comfortable performing these tests yourself, consider consulting a qualified technician to ensure safety and accuracy.

👉 What’s Next?

• Browse our selection of tested surplus starter motors here.
• Watch more of our how-to videos and repair guides on our YouTube Channel.
• Need expert help? Contact us for professional automotive A/C and electrical repair services.