What are you using for a fake car? Do you have an oscilloscope so you can actually see what the pilot is doing when you set 0a? Here are the states for the pilot. If 0a were causing the pilot to stay at 0v, you would get error state E, which the J1772 wikipedia article describes as "No Power". I'm pretty sure that's how EVSEs that have a timer function turn charging off.M_VdM helpfully pointed out that TWCManagerCarAPI v2.zip has the wrong baud rate set on line 193:
baud = 9200
It should read:
baud = 9600
Unfortunately I can't delete or modify the file, but I'm attaching a corrected version. I didn't notice the 9200 setting causing major problems during testing, but looking back there is some evidence it caused messages to be lost/corrupted periodically.
Now that I have a working P1 TWC for testing on, I've discovered that setting it to 0A won't stop it from charging a fake car device! It will only stop a real Tesla from charging. I suspect this means that charge stop requires negotiation using the Tesla proprietary communication protocol. What's really bad about this is it means the countless hours of testing I did with a P2 TWC to try to stop it from charging a fake car were completely wasted!
The only good thing here is it means there are again a ton of options that might stop a P2 TWC from charging a real car... but I have to test them with a real car plugged in, which I really don't like. *sigh*