Most of us, at least once, have gone to start our vehicle only to find that the battery is dead. You find a friend and get a hold of some jumper cables – but now what do you do?
Before Jump Starting
It's very important when jump starting that you correctly identify the positive and negative terminals of the batteries. The positive terminal will have a (+) near it, while the negative terminal will have a (–) near it.
The positive battery cable is often red (but may be black), while the negative battery cable is almost always black. However, polarity signs near the battery terminals are a better indicator of which is which than battery cable color is.
Note: If you accidentally try jump starting with the cables reversed on either vehicle, you will severely damage the vehicle's battery and/or electrical systems.
A diagram showing the proper jump starting setup.
It's also important when jump starting a vehicle that you don't let the clamps touch if any of them are hooked up to a battery. Touching them together can short out the battery and lead to a shower of sparks and/or burns.If you suspect your battery went dead because you left your headlights on, be sure to check the switch and turn them off before you try to jump start the vehicle. Never try to jump start a frozen or leaking battery.
How to Jump Start a Vehicle
Park the booster vehicle next to the dead vehicle, close enough so that the jumper cables will be able to reach.
Make sure both vehicles are in park (or neutral), set the parking brakes, and turn off the ignition on both vehicles.
Open both of the vehicles' hoods and locate the batteries.
Connect one of the positive (red) jumper cable clamps to the positive battery terminal on the dead vehicle.
Connect the second positive (red) jumper cable clamp to the positive battery terminal on the booster vehicle.
Connect one of the negative (black) jumper cable clamps to the negative battery terminal on the booster vehicle.
Connect the second negative (black) jumper cable clamp to a piece of unpainted metal on the engine of the dead vehicle – not on the negative battery terminal.
Make sure the connections are secure, and none of the cables are in the way of moving engine parts.
Start the engine on the booster vehicle and let it run for several minutes.
Attempt to start the dead vehicle.
If the vehicle starts, leave it running and disconnect the jumper cables in the opposite order from which they were connected. If it doesn't start, verify all connections are secure. Give it a few more minutes and try again.
What if the Vehicle Still Doesn't Start?
If the vehicle is cranking well but doesn't start, or doesn't crank at all, there is likely more wrong than just a dead battery.
Verify that the vehicle does indeed have fuel.
Make sure that the battery cables themselves are tight.
At this point, you will likely need to have the vehicle towed to a service center for diagnostics.
What if I Can't Find the Battery?
Not all vehicles will have the battery in the engine compartment. Some may be in the trunk or under the rear seat, and they may not be accessible enough to use jumper cables on. In this case there will be jumper terminals located in the engine compartment. Jumper cables can be attached to these terminals just like they would be to actual battery terminals.
Why Not Use the Negative Terminal on the Dead Battery?
The final connection when jump starting a vehicle should always be put on an engine ground, which is any piece of unpainted metal on the engine. This is done because sparks are not uncommon when making the final connection with jumper cables, and if sparking occurs near the battery (which can emit hydrogen gas when charging) there is a chance that the battery could explode.
Can You Jump Start a Hybrid?
Hybrids can also be jumped or used to jump start other vehicles. The procedure may vary slightly from that used for conventional vehicles, so check your owner's manual for specific information.
Get Your Vehicle Serviced if You Notice:
Battery issues (not holding a charge, leaking, etc.)