Jump-Starting a Car - Part 2
Start the good car's engine and make sure the headlights are off to allow the maximum amount of power to get to the dead battery. Let the good car's engine run a minute or so before attempting to start the dead car. Sometimes you get lucky and the dead car will turn over right away, sometimes it takes a few minutes. If your dead car's interior dome light comes on, it's a great sign that you've connected the cables right. Now shut all doors and dome lights and try to start the car. If it sounds like it's trying to crank but won't turn over completely, give it a few more minutes and rev the engine moderately on the good car. You may also need to play with the cable grips to get a better connection. Normal sparking occurs as you move the cables around. If you couldn't get the dead car to start, see the troubleshooting section further own this page.
Removing the Jumper Cables
Now that your dead car has been successfully jump-started, you can remove the cables in the reverse order that you connected them in. Be careful to avoid letting the cable clamps touch each other:
- Disconnect the Negative (-) cable from the engine block of the car that was jump-started.
- Disconnect the other end of the Negative(-) cable from the Negative (-) post of the good battery.
- Disconnect the Positive (+) cable from the Positive (+) post of the good battery.
- Disconnect the other end of the Positive (+) cable from the Positive (+) post of the dead battery.
Check if the Car Can Restart
After your revived car has been running a few minutes, turn off the engine and see if it will restart on its own, no cables attached. This is a good test to see if your charging system is working, and if successful, it's a good indicator that you won't have problems driving home. If the engine cannot crank on it's own, you'll have to jump-start the car again and it may mean you'll have problems getting home. If your car does not restart on its own, it's a sign that something is really wrong, either the battery is bad or your charging system has a problem. Have someone follow you home.
Jump-Start Troubleshooting Tips
If you tried the steps above and your car still won't start it is possible that the dead battery is not getting voltage from the good battery due to bad cables or a bad connection from the good battery.
- Play with the cables a bit to be sure you get a good connection. You'll see sparking as you adjust the clamps, which is normal.
- Try disconnecting the Negative (-) cable from the dead car's engine block, and try moving it over to the Ground (-) post of the dead battery, if the dead battery is not leaking. Keep in mind there is always risk of battery explosion, but I've never had a problem. Wear protective eye wear! Don't take any chances. Remember, if you don't see your instrument panel light up, or dome light turn on then you don't have a good jumper cable connection.
- Try another set of cables. It could be that the cables you're using are no good.
- Verify once again that all electronics are off. Nothing should be on, the doors should be closed during the cranking process so the dome light is not on.
- Double check that there is no corrosion, rust or anything other than nice shiny metal on the battery posts. Scrape off the corrosion with a fingernail file if you have to, but you want nice shiny posts when you're done.
- If the cables are real warm and you're not having success, it's a sign that your jumper cables have a problem. Jumper cables that are frayed or rusty at the clamps may not work.
- If all else fails, call a tow truck or AAA.
Auto parts stores can quickly diagnose your dead car battery for free! Have your battery tested before you buy a new battery so you know if it is the problem.