Why My Car Won’t Start If the Battery’s Still Good

If you tried a jump-start and your car won’t start, you’re looking at a problem bigger than the car battery. (If it is the car battery, you might have noticed some of these six subtle signs you have a bad battery.)

First, stop trying the ignition. You could overheat your starter if you don't already have a bad one.

Interstate Batteries automotive electronics expert Jeff Barron took a few moments out of our battery testing lab in Dallas to talk through the most common reasons why your car won't start.

"Engines need fuel, spark and air in order to run. You take one of these away, and it will not start,” Barron said. “Engines are essentially a huge air pump with the air intake coming from outside and running through a set of sensors allowing the correct mixture to make it run efficiently."

Any number of failed parts can make your car stall.

If your car won't start, consider all the options before getting a car battery replacement. In fact, a brand new battery can mask whatever problem is keeping your car from starting.

If your car won't start but the battery's still good, there are plenty of things to look for when troubleshooting a car that won't start.

1. Blown or Bad Fuse

If your car won't start but has some power, you may have a blown fuse if the car makes no noise at all and only some electronics work. Don't keep trying the engine and don't try jumping it. Instead, examine its fuse box. You may be able to spot an obviously blown fuse or you may need to test it with a multimeter or a voltmeter. Fuses are inexpensive and, depending on the make and model of your car, not too difficult to replace.

Heads up: Something else caused the blown fuse. What might have drawn so much power through that circuit in the first place? Is it the fuse for the ignition switch, the fuel pump, the engine control module or any other vital part? The only way to know is to get a proper engine diagnostic at your trusted repair shop.

Also, check the battery connections. It might not be the fuse or ignition switch; it could be that your battery cables somehow came loose. You might be able to simply tighten the bolts on the battery terminals and then the car will start right up. How might battery clamps come loose? One culprit could be corroded battery terminals, so be sure to clean corrosion off your battery and remove any buildup on wire terminals and to make sure your car always gets a strong start.

2. Bad Alternator or Ignition Switch

If your car won't start and the electronics fade out, you might have a bad alternator or ignition switch — but you can still jump the battery. Now, the dashboard lights might fade out or some of the accessories might not turn on correctly because of either of these. (This may also be a common sign that your battery is nearly dead.)

Now, it's probably the ignition switch if the car starts and then suddenly stalls. A failed ignition switch can turn on the car, only to cut power to the fuel system, which shuts the car off. Ignition switches can also kick off a host of other troubling issues, such as stalling while you drive or your car key getting stuck.

If you jump the car and, as you're driving, you notice the dashboard lights or headlights brighten or weaken depending on the RPM, the problem may be the alternator. (And you'll likely need to replace the car battery with it.) At low RPM, such as when you're waiting at a stoplight, the battery voltage may drop to less than 13 volts.

If you jump the car and can watch the voltage on the vehicle's voltmeter, you should see it climb steadily from 12 to 14 volts. If it hovers or stays below 13,1 volts, then you've got alternator problems. Your car battery should have 14 volts while the engine is running. (If you're checking the battery with a voltmeter with the engine off, a good battery will show more than 12,75 volts.) Anything less than that while the engine's running, and you know you've got a bad alternator. Get to a repair shop as soon as you can.

3. Faulty Starter Motor

If your car makes clicking noises, you may have a bad starter but the battery is good.

Clicking noises usually point to an issue with the electrical system. The clicking is the sound of the starter motor spinning. The starter is trying to make the electrical contact, which is how the engine cranks — and either the car battery or the starter itself is too weak. One loud click means the starter's not getting enough power. Rapid clicking means the starter's getting power but that power's not going to the engine.

That means if you hear rapid clicking instead of that reassuring vroom when you try to jump a car, it could be the starter. Don't keep trying the key or you really will blow out the starter.

4. Bad Engine, Body or Power Control Module

If your engine makes a strained, whirring noise when you try to jump-start it, you may have a bad engine control module, body control module or power control module. If you keep pressing the ignition, you'll hear the switch, the click of the starter, the turn of the engine — but no start.

Now, the engine will keep whirring, but don't do that. You may burn out the starter. Starters aren't designed to run for more than 30 seconds at a time, as in, just enough time to get the actual engine running.

These control modules manage the fuel, air and spark the engines need to get going. If one of them is out of commission, not even jumper cables will get you going. That's when you need a repair pro with tools and parts to get your car starting again.

5. Bad Fuel Pump or No Gas

If your engine sputters briefly instead of starting, you may have an empty fuel tank, a clogged fuel filter or a bad fuel pump if you're trying to jump your car and it still won't start. That sputtering noise will be brief. That's the engine burning up a few drops and sucking in too much air for the fuel mixture.

If the gas tank is empty, you have a straightforward fix. Hitch a ride to your nearest gas station for a gas can and a gallon of your car's favorite beverage.

If it's the fuel pump, get to a professional repair shop for help.

6 Signs That Your Car Battery Really Is the Problem

What if the problem really is the car battery? Here are a few signs that the problem is a bad battery, not the alternator, ignition switch or bad fuel pump.

1. One big, loud click is the sign of a dead battery. If you only hear one loud click when you try the ignition, your battery is too dead to keep trying the starter. If the starter were the problem, you'd keep hearing clicks (until the starter dies. Please, don't keep trying the ignition after 30 seconds.)


2. Get a jump start and get on the road. Then, watch your vehicle's battery gauge, if it has one, while you're at a stoplight. Specifically, you want to have the transmission in drive but holding the brake down. At a low RPM, a weak alternator will lean on the battery, and you'll see some odd engine behavior. However, if the voltage stays low but the engine's fine, the battery is your problem.


3. Try charging the battery for 4-8 hours and then start the engine. If your car starts once and everything runs smooth for a day, even when you're idling, but then the car dies again less than 24 hours later, you've got a dead battery. It may not be able to stay charged up. Like an old iPhone, it may go from 100% to dead, no matter how well you try to charge it.


4. Let's say you can't get a jump right now. Turn on your headlights with the engine off and watch the beam shine on something for 60 seconds. If the headlights dim or flicker within a minute, you've got a drained or weak battery.


5. Batteries protect your car's memory. If you're getting new warning lights when you try to start the car after a couple of weeks, but they fade if you've driven a few days in a row, you've a battery problem. The battery may not have been able to keep power up to the sensors, or if it was too weak at any point right after starting the engine, the battery may be about to die.


6. Let's say you just bought the battery. Open the hood and look at it. Do you see a small round sticker on it? That's generally the month and year that it was last charged up and put on the shelf to sell. If your new battery sticker has a “charged up” date older than six months, you likely bought a drained battery. Get a replacement quick — and check the date on it before paying.

Now, a dead battery can be a symptom of a dying alternator or a deeper electrical issue, including broken cables somewhere along the line. As long as you regularly get a battery test with every oil change, you'll stay ahead of any battery problems.