The Secrets of ColecoVision Games

ColecoVision Super Donkey Kong Jr

From May 1989 Vol 5 #5 AIM newsletter Pg 9

Public Domain Version of Donkey Kong Jr 5 Screen release

The 5th screen does not automatically reveal when playing this version. 
To make it reveal you must enter the player selection screen and press the controller fire buttons on both sides and hold them while you push the following sequence: 1 - 3 - 2 - 1 - 2 - 1 - 2. 
The game will then automatically acknowledge you are playing the 5 screen game. Remember that it only works on the 5 screen public domain version of Donkey Kong Jr.