Batteries draining

[rdoimages]

I have tried searching but there are 800 mentions of battery drain.
I am experiencing drained batteries after 2 or 3 days of the truck sitting unused. The batteries are brand new, the positive cable is a brand new OO cable, the alternator is nearly new and the regulator is fairly new. The only constant drain I know of is the radio memory.
Anyone have any ideas of anything else that could be causing the drain? I need to get the truck running to check alternator output I guess. It will start fine when charged and it will be good for a day or two and then it's drained enough to not turn it over at all.


89 F-350 sc 2wd DRW 7.3 ATS 088, C-6 with Gear Vendor and a rats nest of wiring that was free with purchase.
00 Excursion limited, 6.8 4x4

 

[MTKirk]

You might want to replace the ignition switch, under the dash on top of the steering column. They are notorious for getting sloppy & out of adjustment, leaving something on when it should be off.

But first; To trouble shoot the system, turn the truck off. Pull neg battery cables, then pull positive battery cables. Connect a ammeter between positive battery terminal and positive cable, reconnect this battery's negative cable (you can leave the other one unconnected). If your ammeter shows current flowing you can start pulling fuses to radio, dash lights, etc. till you don't have current flowing. If you suspect the alt & craptastic stock regulator (update to 3-g immediately) you can unhook the wires to it as well. Theoretically, it could be the starter or solenoid, but I kinda doubt it- I'd unhook it last.

 

[laserjock]

Touch your alternator to see if it's warm when the engine is cold. Have a Subaru that eats alternators and the symptom is drained battery.

 

[IDIoit]

disconnect batteries.
isolate driverside cables so they dont contact anything.
put ohm meter on pass side battery cables, and start pulling fuses until there is no continuity.