Jump-starting a car with a weak battery can be dangerous if proper procedures are not followed. Always consult your owners manual for specific instructions.
Step 1. Position the cars close enough for jumper cables to be connected, but not touching.
Step 2. The transmission on both vehicles should be in park, or in neutral with a manual transmission. The parking brake should be on and the ignition and accessories off.
Step 3. Connect one end of the positive cable to the positive terminal of the good battery.
Step 4. Attach the other end of the positive cable to the positive terminal of the disabled battery.
Step 5. Connect one end of the negative cable to the negative terminal of the good battery.
Step 6. Attach the other end of the negative cable to the engine block or alternator mounting-bracket of the disabled car, as far from the battery as possible. Do not connect the negative cable to the negative terminal of the dead battery.
Step 7. Start the engine on the car providing the jump. When attempting to start the disabled vehicle, don't crank the starter for more than 20 seconds. If it doesn't start in 20 seconds, wait two minutes before trying again.
Step 8. When the disabled car is running, disconnect the jumper cables in the reverse order from which they were connected.
Source: AAA
