There’s nothing more frustrating than getting into your car, turning the key or pressing the start button, and realizing it won’t start. The dashboard lights come on, the radio works, and you have full accessory power active, but the engine remains silent. If you are encountering this issue, you’re not alone. This blog post will guide you through understanding why this happens and how to diagnose and fix the problem.

Understanding full accessory power

Before we dive into diagnosing the issue, it’s essential to understand what full accessory power means. When you turn the key or press the start button in your car, a series of events occur. One of which is a signal to activate all electronic systems such as headlights, radio, and dashboard lights. This is known as full accessory power. It is a sign that your car’s battery and alternator are functioning correctly. However, just because you have full accessory power doesn’t mean your car will start.

Why won’t my car start?

There could be several reasons why your car won’t start even though you have full accessory power. Here are some of the most common culprits:

  • Dead battery: This is the most common cause of a car not starting. If your battery is dead, it won’t have enough power to start the engine, even though you have full accessory power.
  • Faulty starter motor: The starter motor is responsible for turning the crankshaft and starting the engine. If it fails, your car won’t start.
  • Bad ignition switch: The ignition switch is what sends power from the battery to the starter motor. If it’s faulty, it won’t be able to send the necessary power to start the engine.
  • Fuel system issues: If your car has a fuel delivery problem, such as clogged fuel injectors or a faulty fuel pump, it won’t get enough gas to start.
  • Faulty spark plugs or wires: Spark plugs and wires are responsible for creating the spark that ignites the fuel in the engine. If they are worn out or faulty, your car won’t start.

Diagnosing the issue

To determine why your car won’t start, you’ll need to do some troubleshooting. Here are a few steps you can take:

  1. Check the battery: If you suspect a dead battery, use a multimeter to check its voltage. A healthy battery should have a charge of around 12.6 volts.
  2. Inspect the starter motor: If your battery is in good condition but your car still won’t start, it may be due to a faulty starter motor. You can try tapping on it with a hammer or wrench to see if that helps. If not, you may need to replace the starter motor.
  3. Test the ignition switch: Use a multimeter to test the voltage at the starter while someone turns the key or presses the start button. If there is no power going through, your ignition switch may be faulty.
  4. Check the fuel system: If your car is not getting enough gas, it won’t start. You can check for any clogs or leaks in the fuel lines and test the fuel pump to see if it’s functioning correctly.
  5. Inspect spark plugs and wires: Worn out or faulty spark plugs and wires can prevent your engine from starting. Replace them if necessary.

Fixing the issue

Once you have identified the problem, you can take steps to fix it. Here are a few solutions for common causes of a car not starting:

  • Dead battery: If your battery is dead, you can try jump-starting your car with jumper cables or replacing the battery altogether.
  • Faulty starter motor: In this case, you will need to replace the starter motor.
  • Bad ignition switch: A faulty ignition switch will need to be replaced.
  • Fuel system issues: If there are any clogs or leaks, you can try cleaning them out or repairing them. If the fuel pump is faulty, it will need to be replaced.
  • Faulty spark plugs or wires: Simply replace these components to fix the issue.

Common Reasons Why Your Car Won’t Start

Even though you have full accessory power, several components need to work correctly to start the engine. Here are the most common reasons your car might not start:

  1. Battery Issues
  2. Starter Motor Problems
  3. Ignition Switch Failure
  4. Fuel System Issues
  5. Engine Management System Faults

Battery Issues


  • Lights and radio work but are dim or flicker.
  • Clicking noise when you turn the key or press the start button.


  • Use a multimeter to check the battery voltage. It should be around 12.6 volts when fully charged.
  • Inspect battery terminals for corrosion or loose connections.


  • Clean the battery terminals and tighten connections.
  • Jump-start the car using jumper cables.
  • Replace the battery if it is old or no longer holds a charge.

Starter Motor Problems


  • A single click or series of clicks when attempting to start.
  • No sound at all when turning the key.


  • Check for power at the starter motor using a test light or multimeter.
  • Listen for a click sound from the starter solenoid when attempting to start.


  • Ensure all wires to the starter motor are secure.
  • Tap the starter motor lightly with a hammer while someone turns the key—sometimes, this can free up a sticking starter.
  • Replace the starter motor if it is faulty.

Ignition Switch Failure


  • Dashboard lights do not illuminate.
  • No response from the starter when turning the key.


  • Check if other electrical accessories work (radio, lights, etc.).
  • Test ignition switch continuity with a multimeter.


  • Replace the ignition switch if it is faulty.

Fuel System Issues


  • Engine cranks but does not start.
  • Strong smell of gasoline.


  • Listen for a humming sound from the fuel pump when turning the key to the “on” position.
  • Check fuel pressure at the fuel rail using a fuel pressure gauge.


  • Replace the fuel filter if it is clogged.
  • Replace the fuel pump if it is not working.

Engine Management System Faults


  • Check engine light is on.
  • The car won’t start despite having fuel and spark.


  • Use an OBD-II scanner to read trouble codes from the engine control module (ECM).


  • Address any specific trouble codes indicated by the OBD-II scanner.
  • Check and replace any faulty sensors (e.g., crankshaft position sensor, camshaft position sensor).

Preventive Measures

To avoid future issues related to a car not starting despite full accessory power, consider the following preventive measures:

  • Regularly inspect and maintain your battery and charging system.
  • Keep your starter motor and ignition components in good condition.
  • Schedule routine maintenance for the fuel system.
  • Stay on top of engine management system updates and diagnostics.


Experiencing full accessory power but a car that won’t start can be a perplexing issue. However, understanding the common causes and knowing how to diagnose and fix them can save you time and frustration. By following the outlined steps and preventive measures, you can ensure your vehicle remains reliable and ready to start every time you need it.

If you’re still having trouble or prefer professional assistance, don’t hesitate to contact a certified automotive technician. They have the expertise and tools necessary to diagnose and repair complex car starting issues.


Q: What should I do if my car still won’t start after trying all the diagnostic steps?

A: If you’ve tried all the troubleshooting steps and your car still won’t start, it might be time to consult a certified automotive technician. They have the specialized tools and expertise to diagnose more complex issues that might not be immediately apparent.

Q: Can a dead battery be recharged, or do I need to replace it altogether?

A: A dead battery can often be recharged using a battery charger or by jump-starting your car. However, if the battery is old or no longer holds a charge, it will need to be replaced.

Q: How often should I replace my spark plugs?

A: Spark plug replacement intervals can vary based on your vehicle and the type of spark plugs used. Generally, it’s recommended to replace them every 20,000 to 40,000 miles, but always consult your vehicle’s owner manual for specific guidelines.

Q: Is it safe to tap the starter motor to get it working?

A: Tapping the starter motor can sometimes free up a sticking component, but it’s only a temporary fix. It’s safe to do this as a temporary measure, but you should plan on having the starter motor inspected or replaced to prevent future issues.

Q: How can I tell if my ignition switch is faulty?

A: Symptoms of a faulty ignition switch include dashboard lights that do not illuminate and no response from the starter when turning the key. You can diagnose it by testing the switch continuity with a multimeter or having a professional technician inspect it.

Q: What are the signs of a failing fuel pump?

A: Signs of a failing fuel pump include an engine that cranks but does not start, a strong smell of gasoline, and no humming sound from the fuel pump when turning the key to the “on” position. Testing the fuel pressure or listening for the pump can help confirm this issue.

Q: Will a failing engine management system prevent my car from starting?

A: Yes, a failing engine management system can prevent your car from starting. This is usually indicated by a check engine light and necessitates using an OBD-II scanner to identify and address trouble codes.

Feel free to reach out to an automotive professional if you are unsure about any process or need further assistance.

Read More: The Ultimate Guide to Car Accessories for Men

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Car Accessories and Gadgets,

Last Update: May 26, 2024