Turn signals not working, blowing fuse
It looks good but how do I test it?
How is that wire different than the rest of the circuit?
Not sure what you're asking.
You've proven that something conductive after the fuse is touching ground. So now look for bare wires or connectors that could be touching body or the engine/trans. Any place that wire is pinched, rubbing, hanging, or melted is what I'd be looking for.
The segment in the engine bay could be laying on the exhaust manifold or rubbing on something, that's what I was thinking. The book shows CE40 may also have other wires in it, one back to the reverse lights and another optional one.
See what matches on your car to what is in the book.
You can always isolate that section by disconnecting at the bulkhead. Its just not the easiest connector to remove. Take your time.