Jmedlock

2004 grand Cherokee has constant voltage draw on fuse box when key is off and out. Disabled malfunctioning alarm, still kills battery. New battery was installed. Connections at battery, starter, alternator are good. Any advice would be appreciated.

dave1123

Welcome to CF!

Start with a fully charged battery, then disconnect the positive (+) cable and put one lead of an ammeter or multimeter (DVOM) on the battery post and the other on the cable end. You shouldn't be drawing more than about 25 milliamps (0.025 amps) for the memory of the radio, clock, and the PCM (Powertrain Control Module, brain, computer). You may have to wait about 20 minutes or so for the different modules to go to sleep. If you have more draw than that, start pulling fuses until you find the culprit that drops the draw. Don't forget the inside fuse box as well. Make sure all the lights, even courtesy lights are off. Sometimes it's the glove box light doesn't go off or the underhood work light is still on. Your 04 might have an IOD fuse (Ignition Off Draw). That's the one that powers the memory circuits. After checking all the fuses and you still have a draw, disconnect all 3 wires from the alternator, there might be a bad diode in the bridge rectifier inside it. That will keep the field energized all the time.

WARNING! If you have the meter set on a very low range, don't open the doors! It might blow the fuse in the meter. Be sure the meter setting is high enough before you power anything up.

Newer cars have an IOD fuse so that if the car is left parked for more than 2 weeks, the draw may drain the battery enough so it won't start. In this case you pull the fuse when you park it.