ALT.S circuit -- current draw problem

[gallilaw]

I am working through some electrical problems, with this complication:

The usual preliminary method of testing for parasitic current draw is to disconnect the negative battery cable and connect a multimeter's probes to the terminal and to the cable, to measure the current flow. The multimeter should be set to test for mA (milliamps).

The ALT.S circuit won't let me do that. If I REMOVE the ALT.S fuse from the main fuse box near the battery, I can test current draw using the multimeter in line with the negative terminal and cable. The system shows about 70+ mA when awake, and only about 5 mA when the system goes into sleep mode.

But if I keep the ALT.S fuse in place, the multimeter starts beeping and, if I wait too long, blows a fuse.

I have a serious current draw problem, and I guess I should conclude that it's through the ALT.S circuit.

Has anyone else had this problem -- that you can't test the current draw through the usual method with the ALT.S fuse in place?

Thanks.