Car Won’t Start But Lights Still Work – What’s Going On?


Picture this; you’re just about to head out to work, you climb into your car, turn on the ignition, and… nothing. Your lights and accessories seem to still be working for the most part, but the engine refuses to turn over. It’s a scenario you never want to have happen, but if you’re reading this article, odds are it may have already happened to you.

There are several potential causes of an issue like this. It could be a problem with your car’s ignition system or the starter motor, or it could be an electrical issue like a blown fuse or fusible link, or even a dying battery.

Today, we’ll go over some of the problems that can leave your car in this state, and we’ll explain why they happen and how you can deal with them.

Related: Why Does My Car Turn Off While Driving?

Dying Battery

You might be slightly confused as to how your lights and accessories can still work with a dying battery even though it doesn’t have enough charge to start your car.

Related: How Long Can a Car Battery Sit Unused?

The answer is pretty simple; most of your car’s accessories draw far less amperage than the starter motor, so a battery that is close to dying completely can still hold enough power to operate your car’s various accessories in most cases.

Things like the radio, headlights and other electronics don’t generally draw more than 20-30 amps when they’re on. Compare this to a starter motor, which requires 300 amps to start, and you can see how this would work. 

A battery can lose its charge for a few reasons. If you’ve accidentally left your headlights or interior lights on for a long period of time, this can easily drain your battery. This is perhaps the most common reason why batteries fail.

A battery can also die if it becomes corroded, if the alternator fails to charge it properly, or if it is ever exposed to extremely high or low temperatures. It can also die if it’s left sitting for an extended period of time, or even simply due to old age. 

How to Fix It

First, you should test your battery to determine if it is in fact the cause of the problem. You can use either a voltmeter or a battery hydrometer to determine how much charge the battery still has in it; whichever one you prefer will work.

If the battery isn’t completely toast, you can try charging it and see if that solves your problem. There are chargers available that are specifically designed for recharging car batteries, or you can try jump-starting your car with another car and driving around for a while afterwards to get some charge back into the battery. 

If your car starts up normally after charging the battery, then you’ve solved the problem. Just make sure in the future to treat your battery with care if you don’t want this to happen again.

If your car doesn’t start but you’ve determined with certainty that the battery isn’t defective, it means the problem lies with another one of your car’s components.

Blown Fuse or Fusible Link

If you’re unfamiliar with what a fuse is or how it works, a fuse is a safety device designed to prevent too high of a current from flowing through a circuit.

Fuses contain a strip of metal that melts when a high current is passed through it; when it melts, the circuit is broken and the current stops, hopefully preventing damage to other electrical components within the circuit.

Related: Why is My Turn Signal Blinking Fast?

A fusible link has the same function as a fuse, but looks different and is used in slightly different applications. Fuses are located in the fuse box, and have a plastic body with two metal sockets that plug into the fuse box. In contrast, fusible links are usually found as a part of the car’s wiring harness and resemble a length of colored wire.

Photo by ChrisFix. Fusible links are labeled as “Fuse Link”

The difference between fuses and fusible links is that fuses have no tolerance for amperage levels above their maximum rating, while fusible links do have some tolerance. This makes fusible links more suited for use in circuits that experience brief surges in their current. 

How to Fix It

A blown fuse or fusible link can’t be fixed as such; you’ll need to replace this component if it does break. Luckily, fuses and fusible links are dirt cheap, and you can buy a large pack of them for about $15-20. 

It’s pretty easy to diagnose a blown fuse or fusible link too. The body of an automotive fuse is semi-transparent plastic, and in an intact fuse you should be able to look through the body and see a small wire running from one of the fuse prongs to the other. If this wire appears to be broken, the fuse has blown. 

To diagnose a blown fusible link, pop your hood and inspect the wiring harness. Look for a wire that appears melted or burned. If you find such a wire, odds are it’s a blown fusible link. 

Bad Ignition Switch

The ignition switch is, as you may know, the part of your car responsible for activating the car’s electrical systems. The ignition switch isn’t the same thing as the key barrel where you insert the key; rather, the key barrel connects to the ignition switch. The barrel and the switch themselves are two distinct parts.

A bad ignition switch can sometimes deliver power to your car’s accessories and other electrical components, but fail to deliver power to the starter motor. This will leave the lights and other accessories totally functional, but the car will be unable to start. Of course, a really broken ignition switch may fail to activate anything at all.

An ignition switch can fail if it is exposed to high temperatures of high humidity levels. It’s also possible for the contact points within the switch to become oxidized over time, which can also cause the switch to stop working.

In general, though, you’ll have plenty of warning if your ignition switch is failing, since they usually start failing intermittently and don’t often completely die all of a sudden.

This diagram displays the three parts that are affected by the recalls for the Chevrolet Cobalt, Pontiac G5, Saturn ION, Chevrolet HHR, Pontiac Pursuit, Pontiac Solstice and Saturn Sky.

There was also a case in 2014 when GM recalled about 800,000 cars due to a faulty ignition switch some of the cars affected including

  • 2003-2007 Saturn ION
  • 2005-2010 Chevrolet Cobalt
  • 2006-2011 Chevrolet HHR
  • 2007-2010 Pontiac G5
  • 2006-2010 Pontiac Solstice
  • 2007-2010 Saturn Sky

How to Fix It

It can be a little tricky to diagnose a busted ignition switch, certainly more so than determining if one of your fuses has blown. However, if your gauges and dashboard lights don’t light up when you turn the key to the “Accessory” position, it’s a good sign that your ignition switch has gone bad.

If your ignition switch is just starting to go bad, you may notice some other symptoms of this. You may be able to start your car briefly only to find that it dies almost immediately after, you may experience flickering dashboard lights or a radio that cuts in and out, and in some cases you may find that the engine continues to run even after removing the key.

If you’ve determined that the ignition switch is indeed the cause of the problem, there’s no real way to repair it. You’ll have to take your car into the shop to have it replaced, or if you’re handy enough to replace it yourself you can try going that instead.

Bad Starter Motor

The starter motor, as the name implies, is used to start your car’s engine. The starter motor is powered by your battery, and is either attached to the transmission or to the engine itself

In a four-stroke engine like you’ll find in all modern cars, only the third stroke of the piston is the combustion stroke; the first two strokes are the intake stroke and the compression stroke, respectively.

An engine can only turn under its own power once combustion has occurred, so the starter motor is necessary for the engine to complete the first two strokes when it starts up.

There are numerous things that can cause a starter motor to fail. Parts of the motor can wear out over time, or the wiring connecting the motor to the battery can come loose.

The connections between the motor and the battery could also be dirty, or there could be an oil leak that has clogged the motor up (which is another issue in and of itself). 

How to Fix It

When diagnosing a bad starter motor, you should first test your battery’s charge and inspect the battery terminals and cables. Trouble starting your car is more likely to be the result of a bad battery than a bad starter, so there’s no point in messing around with your starter motor if you’re not sure that this is the cause of your problems.

If you’ve determined that the battery is not the issue, the next step is to test the starter control circuit. There are several parts within the starter motor assembly (such as the starter solenoid) that make up the starter control circuit, some of which can fail independently of the motor itself.

Use a voltmeter to test the starter control circuit, and see if it gives you a voltage reading. If you don’t get a reading, this is a sign that the starter control circuit has failed. If you do get a reading but the motor still doesn’t run, however, it means that the motor itself has most likely failed.

Damaged Ground Cable

You might know the ground cable in your car better as the negative battery cable. The positive cable (the red one) connects the battery to the car’s computer, while the negative cable (the black one) connects to your car’s chassis and completes the battery circuit.

Your car’s ground cable can wear out over time thanks to the vibration caused by the running engine. The inside of a ground cable contains a bunch of steel strands wrapped around each other. Friction caused by the ribbons moving against each other can eventually cause them to snap, which will result in a weakened electrical connection.

A damaged ground cable is more difficult to deal with than a dead battery, since it’s not possible to jump-start a car with a broken electrical connection. 

Related: Can You Jumpstart a Car In The Rain?

How to Fix It

First, you’ll want to examine your battery cables to see if they look corroded. Look for any burns, cracks, or holes in the cable, and take note if the material wrapped around the cable feels brittle to touch. Corrosion usually occurs near where the cable connects to the battery terminal, and can appear as a small amount of whitish-green powder.

Corroded battery cables can’t be fixed, so you’ll have to have yours replaced if you find they’re in rough shape. It’s a good idea to periodically check your battery cables so you can catch any damage before it gets too bad. Driving with a bad connection can potentially damage some of your car’s other electrical components.  

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