What do you mean by "it dies when you turn the key"? Do you mean all the dash lights go out or are you referring to the engine dying? The engine should die when you turn the ignition switch. You know that; that's why the confusion.
Do you have a test light or voltmeter? When it's acting up, measure the voltage on the battery posts, then move one probe to the battery cable clamp, then move the other probe to its cable clamp. It's best to turn on the head lights when taking these three readings to help insure it stays in the bad state. A fully charged battery will read very near 12.6 volts. You're looking for the place where that voltage goes down, possibly all the way to 0 volts. As soon as you find a much lower voltage right after moving a probe to the next point, you just crossed over the bad connection.
Next, move the negative probe from the battery cable to a paint-free point on the body. A bolt usually works well. If the voltage is low now, look at the small black wire from the negative battery cable where it bolts to the inner fender.
Move the positive probe to the stud in the fuse box. A fairly fat red wire from the battery positive cable bolts there. Put the probe on the stud, not the terminal crimped to the end of the wire. If voltage is low now, remove the nut, clean the terminal and base of the stud where it makes contact with sandpaper, then tighten that nut.
Wednesday, February 23rd, 2011 AT 11:22 PM