Chrysler Repair: Battery discharges if not driven: Chrysler 300M, resistance one, volt ohmmeter

Question
Hello...

I have a 1999 Chrysler 300M. The vehicle has a power drain which I can not find.  If the vehicle is driven everyday it will not go dead, but if not driven for two days it will be totally dead.  It currently has its second brand new battery so that is not the issue.  Any advice???

Thanks,
Ken

Answer
Hi Ken,
I have the '98 manual for the Intrepid/Concorde but suspect the '99 300M has a similar electrical system because it is the same body, correct?  Here is how to go about finding which circuit is carrying away the current:
Chances are that one of the interior lights is on all the time (glove box, under the hood, in the trunk). So look carefully to see whether those bulbs are truly going off when the door is closed.
The other approach is to use an ohmmeter to measure the resistance that each of the fuses is supplying current to.
If you can get a hold of a volt-ohmmeter with a digital readout you could differentiate a too low but finite resistance from moderate acceptable resistance. One of the fuses is supplying power to a circuit with a too low resistance and that is why the battery is running down. Begin with the fuses under the hood in the power distribution center box near the battery. One pin socket of each fuse is the hot side which has 12V on it from the battery, so don't touch that one with the meter in the ohmmeter position, just use the voltmeter to find the "cold" pin after removing each fuse. The 'cold' pin is the one to measure for resistance(i.e. all the lamps and devices are attached to that one). If you set the meter to read ohms (200 ohm full scale) and touch the - lead  of the meter to any shiny metal body surface and the + lead to the cold pin of the fuse socket it should read more than 50 ohm, the more the better. Make sure all the doors are closed when you are doing the measurements.
Then the question is how to find which of the many items on a given fuse that is suspect is causing such a low reading.
So first go thru the power distribution box under the hood to find a fuse whose cold side reads less that 50 ohm, and let me know which one(s) it is (its label by number and/or purpose). That fuse will supply several fuses in the fuse box under the dash, so we will do the same testing on those fuses once we identity the 'master' fuse which is carrying too much current.
Then we can go on from there to isolate what component on that secondary fuse is drawing the current and check it out.
Roland