Car Won’t Start With Jump

A dead battery in your car is something you know. A simple jump start should get it running again, but what happens when it doesn’t? When the car won’t start with a jump, you are facing bigger issues than first imagined.

If your car won’t start with jump, it’s possible there’s an issue with the connection or bad jumper cables. It could be caused by a dead, defective or malfunctioning battery or an issue with the neutral safety switch or starter.

In this guide, we evaluate the top causes of a battery that won’t jump. You will also learn how to resolve each issue.

Reasons Car Won’t Start with Jump

1. Bad Connection

Even if the battery looks good, it could have a problem connecting the jumper cables to the terminals. Check the connections and terminals for any signs of corrosion.

This is a simple problem to solve. Baking soda and water can be used to remove corrosion. Make sure you have secured everything before jumping it again. 

2. Bad Jumper Cables

Don’t look past the obvious as you jump right into what bigger problems might exist. If you have a set of cheap or thin jumper cables, it’s possible that they are failing you. To allow the bad battery to recharge, you should leave your battery cables in place for at least 5 minutes.

Even if you have a good set, the cables can break over time, especially if you don’t take care of them. You can try another set or a portable starter to jump start. You might have to buy thicker jumper cables if your engine is larger.

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3. Battery for dead cars

Most problems stem from an entirely dead battery, with either a damaged cell or short circuit. These could result in an electrical problem. The jump start isn’t going to work when the battery can’t be rejuvenated.

Smaller jumper cables won’t be able to supply the power themselves without charging the bad battery with the good battery for a while, so if the battery can’t receive the power it won’t be enough.

The battery may have started to fail, as you might notice the lights dimming or the time it takes for the light to turn on. Your local auto parts store or repair shop will bench test the battery to determine if it’s beyond jumping. 

4. Malfunctioning Starter

When the key gets put in the ignition, it’s the starter that activates the engine. So it cranks, power transfers from the battery and to the starter.

However, when the starter begins failing, you won’t be able to crank the engine, even if you try jump-starting the battery. You will most likely hear the click sound that signals that your starter is failing. 

5. Bad Neutral Safety Switch

The neutral safety switch on automatic transmissions keeps your vehicle from starting if the car isn’t in Park or Neutral. The neutral safety switch can fail, and your engine may experience a no-start condition.

It is possible to shift into Neutral and see if that causes the switch to start. If it does not, you may have difficulty determining if neutral safety switches are defective. 

6. Defective Alternator

Although a bad alternator may not immediately cause the problem, your vehicle could shut down as soon as you take out the jumper cables. The battery doesn’t work alone. The alternator is responsible for keeping it charged and it runs the vehicle’s electrical system of your car when the engine is going.

If the alternator fails, the battery won’t get recharged. It doesn’t matter how much you jump it, the battery will die again as soon as the juice drains. A bad alternator can cause symptoms similar to dead batteries. This is why so many people mistakenly confuse them. The alternator can be tested by your local auto part store. 

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Troubleshoot a Car That Won’t Jump Start

1. Let the battery recharge

Allow the jumpstart cables to rest for at least a minute before you attempt to start the car. The dead battery will get a little charge if the car is running.

Sometimes it is difficult to restart a battery if the charge has dropped. The cables alone won’t provide the electrical power needed, but a few minutes should do the trick. 

2. Jumper cables/Connections

If the battery doesn’t seem to be getting a charge, check on the jumper cables. The current could not flow if the rubber coating on the cables becomes warm. Try using another set of jumper cables, or a container.

It is also important to inspect the battery terminals. You may be looking for corrosion if you see greenish or chalky-white substances. The corrosion could prevent the battery from getting enough charge. Clean the corrosion by removing the jumper cables. After the connectors and posts are cleaned, jump-start it again. 

3. Conduct Systems Checks

If nothing else has worked, it’s time to start looking at the major systems to see where the fault could be. There aren’t a lot of major systems that could be causing a no crank situation. Even though many people claim that a clogged filter or a spark plug issue will cause you to think the battery is dead, this isn’t true. The engine can still crank but it won't start in either of these situations.

To see if the car can be started, you might shift into Neutral. The Neutral Safety Switch may have failed. Test or install a new battery to ensure it’s healthy before doing anything else. Otherwise, you want to have the possibly faulty starter bench tested to see if that’s causing your problems.

4. Get help from professionals

If all else fails you can always turn to a mechanic for help. You might need more diagnostics than you can do on your own. You can trust that the car will be towed safely to an authorized location. 

How to Jumpstart a Car

There’s always the possibility that you aren’t jump starting the car the appropriate way. It’s always good to have a quick refresher on the proper steps, so you can assure the battery has the connection it requires. These are some simple steps you can follow:

1. Place the cars together with their hoods facing each other.
2. Open the hoods.
3. Connect one of the red clamps from the jumper cables with the positive terminal of your dead car battery.
4. Connect the red clamp from the jumper cables the the positive terminal on the battery.
5. Connect the clamp in black to the negative terminal.
6. Connect the black clamp to an unpainted piece of metal that is found on the car. Attach it to the terminal on the negative side. Sparks could result.
7. Start the car if it isn't starting immediately. If it doesn’t start immediately, you can wait a few minutes for the battery to charge.
8. Do not remove cables in the same order as you placed them. 

RELATED : What Battery Cable should be removed first, and installed last?

Once the car is running, it’s best to keep it going for at least 15 minutes. You can get more battery charge from your alternator the longer the car runs. You can also test drive the car on the freeway to see if it will charge up. Whatever you do, don’t turn the car off right after jumping it or you might run into the same trouble.