Hello,
So, yesterday i went to start my 99/2000 XJ 4.0 as usual, but nothing happend. It was COMPLETLY dead like the battery had been disconnected.
I jump started the car, but it was like there was a bad connection or something because it took a fair bit before it started. Well, i drove the car to work, and the voltage gauge was around 13 volts, so i did not think more about it (the alternator is also only 4 months old). But when i tried starting the car after work, i was dead again. I cleaned the terminals on the battery and cables, but i did not help. After i put jumper cables on the car it turned over fine but it would not start! and an every more strange thing, was that the electric fan started running, which has never worked while i have owned the car, and the engine was not warm. wtf? There is almost 13 volts on the battery, and the engine now turns over, but does not start, it dies after 3-4 sec.

Can anyone pinpoint me in the direction of solving this very strange problem?
Thanks a lot in advance

 

It sounds like you could have a problem with the coolant temp sensor , maybe a stuck fan relay .

 

The electric fan comes on under 2 conditions. Either the AC is on, or the temp is high enough that the ECU commands it on.

Sounds like you have a parasitic draw. There is plenty of info on how to diagnose a parasitic draw, but the short/skinny of it is that you use either a multimeter between the negative terminal and the negative battery cable to find the actual current draw amount (less than 20mA) or you can go as simple as a test light in the same spot. If the light comes on, you have a draw. Close the doors and disconnect the underhood light. The test light (or multimeter) should show no draw. Of it does, start pulling fuses until you find the one that clears the parasitic drain.

As of right now, you have a no-start condition. Check for spark, then check for fuel pressure. If the car had been recently running, it's probably one of those 2 things.