Electrical issues

rolemodeltom

I have a 2014 Chrysler 300C with about 60xxxkm on it. In the past 3 or 4 months the battery will die over night or over a couple nights. The cluster screen shows white and the gauges act all strange and it will barely have enough juice to start or it wont start at all. The other day I decided to find the source and found a 2.5 amp drain on the battery when the car is off. I put a test light from the negative post to to the negative terminal and pulled all the fuses to find which on was staying on and I found that fuse 7 Exterior Lighting #2 , fuse 6 Exterior lighting #1 , fuse 23 Fuel door/ Diagnostic port, fuse 32 HVAC module/ cluster, and fuse 33 Ignition switch/ wireless module were all staying on. I understand that there will be some systems that stay on when the cars off but I'm not sure which ones and if they can possibly affect other circuits. I'm at the end of my electrical ability and am pretty stumped as to how to fix this.

thecardoc3

Trying to use a test light in that manner doesn't work anymore. When ignition systems used to turn everything off that was sufficient, but today keep alive memory power makes that obsolete. Today specific modules that "sleep with one eye open" stay awake with the reduced system power because of the voltage drop occurring across the test lamp when it is in series with them. That means by trying to use a test light you get false positive results.

To identify the circuit drawing power top technicians have invested in volt meters that are much more accurate and sensitive than what we used to use. You need to have a voltmeter that is accurate to .05%, and measures into the microvolt range. (X.xx millivolt) When current is flowing, a voltage drop can be measured across the terminals of the fuse that is carrying the current. Any circuit with no current flow will measure 0.00000 volts across the fuse. We even have charts that can approximate what the current flowing across any given fuse is based on the voltage drop across it. This helps identify the circuit that actually has the drain especially when some circuits staying awake and drawing current are normal.