Pulled fuses until I found out what was drawing the most power with the key off, at least 200mA. Its fuse 26 and in the owners manual it lists it as "Battery saver relay, Auxiliary relay box, Restraint Central Module (RCM), Generic Electronic Module (GEM), Instrument cluster". I pulled the power to the radio, no draw there. The only thing I modded with the instrument cluster was with buck converters to power the backlight LEDs but they only get power from the light sockets. Any ideas what I should check next?

 

Yes, fuse 26 in the cab powers several systems, has full time power

GEM is the biggest power draw UNTIL, it goes to sleep, about 30min after doors are closed

Battery Saver relay is held closed by GEM until it goes to sleep which is also a power draw

Best method is to hook up amp meter at battery, then wait 30min(doors closed) to see if the draw drops that will take GEM out of the picture and usually Battery Saver relay

If the draw doesn't drop down after 45min(just in case) then you will need to pull out the radio to get access to GEM to unplug it and see if draw goes down enough

If you have Keyless entry(Fobs) then you should have 60-70mA(0.07amp) after GEM goes to sleep
40-50mA if no keyless entry

 

"If the draw doesn't drop down after 45min(just in case) then you will need to pull out the radio to get access to GEM to unplug it and see if draw goes down enough"

Remember to keep the doors closed so you dont have to wait another 45 mins sitting in cab waiting for GEM to sleep before unplugging it and monitoring the draw. Some folks just keep the window down and crawl through. Others wire up the door sensor and trick it being closed.

 

Just checked the draw after 45 min, it did drop but its reading about 0.1 amps. So the GEM appears to be going to sleep but there is something else on the circuit that is still on.

 

Yes, that's 100mA so a bit high, 30mA to 70mA(0.03 to 0.07amps) is expected, 70mA is if you have keyless entry(fobs)

If you ONLY pull out fuse 26 what is the drain?

 

With fuse 26 pulled I think the draw was about 80mA with keyless entry. I'll check again tomorrow. I'll have to make sure the battery doesn't have an internal short, I pulled the negative off when I was doing some welding and it was disconnected for about a month, when I went to attach it again I couldn't start the truck. Checked the voltage on it and it was about 4v, for a new battery that was about a month old.

 

Batteries sit on shelves for months and months in warehouses and parts store......................you got a bad battery, get it exchanged ASAP so full warranty
And in any case, once a car battery goes down below 9volts it will never take a full charge again, so you might get 2 years out of it

Car batteries are made to deliver alot of AMPs fast, for starter motor, then to be immediately re-charged, they have very thin plates

They make Deep Cycle batteries, that are made for RVs and Marine applications, these have thicker plates so are OK to discharge slowly, and then recharge
Deep Cycle batteries can start engines but its not good for them to generate the 60amps all at once, they like the slow discharge, lol

 

So after a week of the battery disconnected after a lengthy drive, the voltage is sitting at 12.5v. Still don't understand how it died within a month of being disconnected just a month or so ago and now the battery is holding a charge

Edit: Decided to pull the rest of the fuses and got to fuse 17 (cigar lighter, data link connector) and it dropped about 50mA so now its only drawing between 40 and 50 mA. Turns out it was the bluetooth OBD2 reader that I have plugged in there.

 

Yes, the bluetooth readers stay power on looking for a connection
And the OBD2 port has full time power so......................you found the drain