Bill,
I saw the other thread. I thought the problem had been solved. I'm not sure on your meter, but you have the right idea. Any current (amps) reading must be measured in series starting on the largest scale and working down until you have workable numbers.
Why didn't it work when you tried it through the negative cable...who knows! These are issues that cloud the search so don't try to figure them out too.
I don't know what rig this is on but the original post mentions a SBC which I assume is a small block Chevy. Your Malibu doesn't fit this description, and I didn't think Ol Blu did either.
The cycling on and off sounds like a clock that is rewinding itself. I can't think of anything else that would cycle with such perfect timing. A shorted diode trio (?) in a alternator is a common source for a drain but you say the alternator has been given a clean bill of health. This test to prove a good alternator isn't something that the fellow with the nose ring that works at AutoZone can do...to test the diode trio, I think it must be pulled and checked.
Whatever is causing this is too small to pop a fuse. I think pulling fuses will only be relevant if the leak is between the fuse and switch or device. If the leak is in the wiring BEFORE any fuse or switch, you can't use that method to isolate it.
You are on the right track with the meter...connect it in series until you get a good, mid-scale reading then rattle wires and shake things to see if you can make it disappear.
Stuart
