2000 Jeep Grand Cherokee Draining Battery

Question

I have a 2000 Jeep grand Cherokee. I can jump or charge, drive it, then the moment I shut it off it is dead and needs a jump. I have pulled all of the fuses, and bought numerous batteries. It is not the alternator. Something is draining my battery. It seems to do it while it sits and while I drive it. I have had other mechanics look at it with no success.

Through research it seems that these cars have a lot of problems with this type of issue. I'm looking for any help and hoping someone has found the solution to this problem.

Answer 1

If the battery is so dead that immediately after stopping it can't start again, then it is not charging. You say that the alternator is fine, but have you checked the charging circuits?

Check for a static parasitic draw (see my answer to this question, or various others here on similar subjects). Check the current being produced by the alternator, and the voltage across the battery, both with the engine running and off. It should be around 13.5v with the engine running, if the charging system is working correctly.

Answer 2

I also have a 2000 Jeep Cherokee and had the similar problem with the battery not charging. I checked control unit data and found that the computer thought the battery was fully charged: said the car was running at 15 volts while the actual battery voltage was only 10 volts. Basically, ECU was telling alternator not to charge. Turns out the driver in the control unit was shorted out so the battery would not charge. I installed new ECU and now it works fine.

Answer 3

I traced my problem with a multi meter to the remote lock module. It has a constant 12 volts to it and that was the cause. It's located in the passenger front door where the lock switches are. I purchased a used unit from ebay and it fixed the problem.