12.2 volts means the battery is discharged, so your 12.1 volts is not an acceptable reading. I suspect you're going to still have the same problem if you let the vehicle sit for twice as long.
Please allow me to add a few details. Wrenchtech is the first person I have ever run into who understands the need for the jumper wire to short out the amp meter. The reason is anything that creates an open circuit, (break in the circuit), can cause a computer to wake up and need another 10 - 20 minutes to time out again. I use 20 minutes in my stories because there are some '95 Chrysler products that need that long.
Most inexpensive digital amp meters have a common negative jack, a common positive jack for most things, and a separate "10-amp" jack for higher current readings. The highest current reading that can be taken through the common positive jack on most meters is 2 amps. Some computers can draw up to three amps for 20 minutes. There's two problems with using the meter's 2-amp jack. The first is you must disconnect the jumper wire so all current has to flow through the meter to take the reading, then the three amps will blow the meter's internal two-amp fuse. (&* $ ) Start all over! The second problem is if you were to wait for more than 20 minutes, then you remove the jumper, the desired current is too low to be measured accurately on such a high scale. You need to switch the meter to a lower range to get more accuracy. All meters use a "break-before-make" switch that breaks the connection to one of its ranges, THEN as you continue to turn it further, it makes the connection to the next range. That momentary break when turning the switch is enough to cause the computer to wake up again. Poof! Another blown internal fuse.
To avoid all this heartache, remove the negative battery cable, install the jumper wire between the cable clamp and post, then you can connect the amp meter while waiting for the computers to go to sleep. Use the 10-amp range and the 10-amp positive jack on the meter. Disconnect the jumper wire. All current has to go through the meter now and will be measured. When it has dropped below 2 amps, reconnect the jumper wire, then it is safe to move the meter's positive lead to the common positive jack, and switch to the 2-amp range. Remove one end of the jumper wire, and take the current reading. If it is too low and you want more accuracy, reconnect the jumper, THEN switch the meter to a lower range.
Normally that was as far as I went with my wondrous story, but it occurred to me there's another potential pitfall after reading your discussion. When you pull a fuse to see if current drops a significant amount, if it does not, you risk waking up a computer when you put the fuse back in. That would blow the meter's internal fuse again. To avoid this, start over on the 10-amp range, then follow the same steps to get back to the lowest range. In the past we could have made some assumptions about the fuses for each circuit. Tail lights, for example, didn't involve a computer. Same with door locks and power windows. Even by '94, those days are long gone, and everything has a computer involved with its operation. The Engine Computer may need time to go to sleep mode because it is running some emissions-related tests. A Body Computer might stay on for a few minutes to watch for a theft system arming signal, or to turn off forgotten lights. Reinserting a fuse could mimic turning on a customer control, and that could cause a computer to wake up and blow the meter's fuse.
In the '90s, Chrysler said a good, fully-charged battery would have enough charge to crank the engine fast enough to start after sitting for three weeks, if the "ignition-off-draw" current was a maximum of 35 milliamps, (0.035 amps). That is the industry standard unless the manufacturer specifies otherwise. Cadillac used to allow up to 50 milliamps, and that is acceptable for many other brands now. If your battery is going dead overnight, you can expect to find around a half-amp drain or higher. That is equivalent to a # 194 glove box bulb. While that 35 or 50 milliamps is the standard, keep in mind you're looking for something considerably higher if it's killing the battery in a few days. Don't get excited over a drop of just a few milliamps when you remove a fuse.
Tuesday, January 17th, 2017 AT 3:43 PM