I have narrowed my drain down to the rdo batt fuse, and think it has something to do with the ignition switch power cut off, the dark green wire on the factory harness reads .20 volts and from what i have read it should be zero. I started to have the battery drain after i installed a aftermarket head unit, and the factory unit had theftlock. I have read that the constant voltage may be the bcm trying to communicate with the factory head unit. Also when i put the leads of my multimeter between the orange constant wire, and the green ignition switch wire there is a reading of .07 volts, does this mean continuity between the two? Read somewhere on here to check continuity between the two and Ohms does not work on this multimeter... Also had battery and alternator checked, both came out to be good.

Vehicle is a 99 Blazer LT 4 door, Auto 4 Wheel Drive

 

Nobody has any ideas?

 

I can help with measuring but I can't help with your actual issue here. Your meter should have 4 separate sections --> AC volts (ACv), DC volts (DCv), DC Current (DCA), and Resistance (OHMS). You should only need DCV, DCA, and OHMS for a normal 12V electrical system.

When you said: "Also when i put the leads of my multimeter between the orange constant wire, and the green ignition switch wire there is a reading of .07 volts, does this mean continuity between the two?"

What setting did you have your meter on? If you had it on DCV then you measured the voltage difference between the two wires, which doesn't have anything to do with continuity. To measure continuity, set your meter to OHMS (the lowest setting) or the setting which looks like a a small arrow pointing to a vertical line (diode setting). This will measure the resistance between two points. If the reading comes out to zero, then the two points are connected. If you set it to the diode setting, the meter should beep as well indicating low resistance connection. Also, when you measure resistance, always remove power from the circuit (disconnect the battery) as it could harm your DVM.

You mentioned your OHMS setting does not work. In this case you can sort of measure continuity using the DCV setting. I say sort of because you will only be able to tell if the two points are at the same DC voltage and not necessarily connected. If you measure two points while on the DCV setting and the reading comes out to 0V, then the two points are at the same potential (voltage) and may or may not be connected (probably connected).

You can measure the current draw of your total system by setting the meter to DCA and connecting it in series with the circuit under test. An easy way is to disconnect your positive battery terminal, then connect the red (+) lead to the battery terminal and the black (-) lead to the wire you just disconnected. The reading will be in Amps and should be low, as in <200mA (0.2A).

Hopefully this helps you. I can further explain things if you want. Good luck!

 

Thanks for the info.

I used the amperage on this multimeter to measure the parasitic drain, one day i had it under 100 milliamps with the fuse 19 plugged in, then when I tried to read it again about a week later trying to further diagnose my problem, and was reading 14 amps, which seems outrageous and inaccurate. When i used a test light the light would only go of after pulling fuse 19. Im thinking the multimeter i borrowed is broke, or I broke it

 

Yes 14 amps is a very high current draw. It sounds more like the voltage across the battery terminals when the vehicle is running.. And if you did have it hooked up in DCA mode, 14 Amps is probably more than your meter can take (normally around 10 Amps is the max for a meter).

I don't know what you were measuring with the test light, it depends on what points you had it hooked up to. The test light should only tell you if 12V is present at the positive lead of the light. So if you had it connected to the (-) side of Fuse 19 and it turned off after pulling the fuse, that would make sense.