Corrosion between the battery and cable terminals can prevent a vehicle from starting. It may be necessary to remove the disabled automobile's battery cables from the battery terminals and clean both cables and terminals.Replace the battery cable/terminal as soon as possible. Place the shim between the battery post and the cable terminal to allow it to be sufficiently tightened to prevent the terminal from moving on the battery post. If you are unable to tighten the terminal enough to prevent it from moving, in an emergency, you can use a metal shim made from a soda or tin can. Avoid touching any other part of the vehicle with the wrench when it is on the terminal as a large spark and explosion can occur. Use a proper sized wrench to tighten the cable terminal to the battery post. Loose cables can prevent a vehicle from starting yet allow the radio and lights to appear normal. Check that the battery cables are firmly connected to the battery posts.Call a tow truck instead or replace the battery. If you find any of these things, do not jump start the car. Inspect batteries for cracks, leaks or other damage. Put on safety gear (goggles and gloves) if you have it. If it cranks slowly, or not at all, you probably have a dead battery. Does it turn over very slowly, or does it crank quickly? If it cranks quickly, you do not have a dead battery and a jump start will not help. If you do not get a flicker out of your dashboard, you may have a problem with your ignition switch. In most cases, even with a low battery you should see some dashboard lights and get some sound out of the stereo. Put the key in the ignition and see whether your dashboard lights up as usual.Ensure that the doors will unlock when you push the button on the key and/or try to open the door from the outside, the interior lights work, and the clock or GPS (if equipped) moves or powers on.If your headlights are bright, you do not have a dead battery and a jump start will not help. If they are dim, it's likely your battery is the culprit. Are they dim or bright? (Note that in some cars you will need to turn the ignition on to test the headlights).

How to jump a car