I used to hike up the hill when I was in the Boy Scout. Recently I read an article about the monthly hike to Bukit Teraja and notice that it is not on the map.

http://borneobulletin.com.bn/monthly-hiking-trail-bukit-teraja/

You can also search via evevationmap.net

http://elevationmap.net/bukit-teraja-bn#menu2