Yes it’s illegal if you do not signal your intentions before maneuvers. You are legally required to signal before pulling over, pulling into traffic, lane changing, parking, merging, turning right and left, etc. And yes you can get a ticket for failing to signal your intentions.
151 – Change Lanes without Signal – $109 & 2 Penalty Points
170(1) No Signal on Turn – $121 & 2 Penalty Points
Technically, you are required to signal if there is someone to signal to, which makes sense considering the point of a turn signal is to tell other people what you are about to do and/or would like to do! (What a concept!!)
If you are the only person around and driving at 4 AM all by yourself on the road then technically you do not have to signal. But keep in mind you are still required to signal to any type of road user that is present and that includes pedestrians & cyclists, as well as drivers; and this includes people that you may not notice when driving at 4 AM.
I would recommend to just do it as a regular habit. It’s not difficult and safety is improved whenever others can anticipate your actions.
(2) When a vehicle is constructed or loaded in a manner that makes a signal by hand and arm not visible both to its front and rear, or a body or load extends more than 60 cm to the left of the centre of the steering wheel, a driver must give signals as provided by paragraph (1) (a) or (b), and a person must not drive the motor vehicle on a highway unless it is so equipped.