My battery has flattened out 3 or 4 times in the past week. It's been very cold here (-20C). I've read in other threads that a relay might be stuck open causing the battery to drain. How can I check this? Where do I look?

I've monitored the current draw with an Ammeter. With everything off and the key out i'm drawing 170mA. This seems like quite a small amount. Is this higher than normal? I pulled and replaced all the fuses one by one to see if any one would cause the current draw to drop and none did.

Any help to shed some light on my situation would be greatly appreaciated. My neighbours tripping over the extension cord running to my car on the street will thank you.