turned on the headlights and killed the XJ

So I was driving along and noticed that the tach was at zero and the speedo was erratic. I pull in the driveway and let the jeep idle, while its idling i decide to try the headlights to make sure they are still working. as soon as I pull on the headlight switch the jeep dies. Wont start back up either. If I try to start it, it clicks like the battery is dead, but I know that it is not.

Any body out there think they might be able to help with this one, I have checked connections, but am not finding anything wrong.

its a 93 4.0 auto

please help

Last time my vehicle (pre XJ) did that exact thing, it was the battery connection. Take apart all the connections and clean them with scotchbrite or sandpaper, then electrical cleaner, brake cleaner, or spray start, and reassemble. Don't forget the grounds too. If that doesn't fix it, try jumper cables to another vehicle or charging battery. How do you know that it is not the battery?

bad alt... even if your batt was dead.. the alt should have provided the juice while it was running..

you turned the lights on and batt could not provide power for spark and lights.

You need to charge your battery overnight, better would be 24 hours. While it is charging you can clean all cable ends and renew all grounds. After the battery has charged overnight/24 hours you should have it load tested, most any parts chain store will do it for free. If the battery passes, hook it back up, verify 12v static between the posts, then start the engine and measure voltage again, looking for 13.6+ volts, but 15+ volts would indicate a problem.

RINGKONG said:

bad alt... even if your batt was dead.. the alt should have provided the juice while it was running..

you turned the lights on and batt could not provide power for spark and lights.

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Alternators are not generators. If there isn't enough voltage to "excite" the alternator it will not charge.