Sorry, but are you replacing 'pass' with your password? Seems like it might be expecting a password there?
That would explain the unexpected token.
But if it's working for you using cURL, then:
Have you tried using the curly brackets for the data-string parameter?
{ \"auth_token\": \"pass\", \"text\": \"Off\" }
For example, if you look at our earlier
Instapush thread, there the datastring is surrounded by curly brackets.
This is probably because they are using JSON, so the datastring needs to be in JSON format.
I'm not sure if you would need the escaping backslashes, but I would start by leaving them in.