Jumping a car incorrectly is extremely dangerous and can cause considerable electrical damage to either or both vehicles. If you're going to jump a car, here are some things to remember. (The mnemonics are in bold type.)
- Be sure that your jumper cable's handles are in good enough shape that you can handle them without ever touching metal.
- See that your battery terminals are clean and secure.
Now here's the sequence:
- There are two cars involved: Dead & Booster.
- Turn off both cars.
- Red to Dead. Connect the red cable snugly to the red terminal of the dead car.
- Red to Booster. Connect the red cable snugly to the red terminal of the booster car.
- Black to Booster. Connect the black cable snugly to the black terminal of the booster car.
- Ground Black to Dead. Connect the black cable to any piece of metal (other than the battery) on the Dead Car. The radiator cap is a good one. It may spark a little when you do this, but don't worry.
- Start the Booster.
- Start the Dead Car.
- Let them run for a while, revving the engines slightly.
- Disconnect the cables in the Opposite Order:
- Disconnect the ground from the Dead Car.
- Disconnect the black cable from the Booster.
- Disconnect the red cable from the Booster.
- Disconnect the red cable from the Dead Car.
- You are now free to drive the (previously) Dead Car around for 30 minutes or so to allow the alternator to charge the battery. Do not use the lights, heater, radio, etc., unless you absolutely must.
I learned all this the hard way - you don't have to. Sure, I'm a mechanical idiot, but at least I never make the same mistake twice. You don't have to make it once.
If you do, you'll fuck up your sister's truck and it will cost her a lot of headaches, time and money and it won't help your self-esteem.