First of all, is he neutered?? If he is not, then he can be marking, which is different from just peeing when he has to go and simply housetraining won't work for this behavior, the best thing for this would to get him neutered and put a belly band on him until you do so.
There are several ways you can teach him to tell you that he has to go. Everytime before you open the door to take him outside ask him if he has to "go potty." Only do this when you take him out to go out to the bathroom, not when you are going on a walk with him, or taking him outside to play. You may also place a string of bells around the door knob and as you ask him, do you got to go potty, ring the bells. After a while he will realize what you are asking him and he will either show you some sign that he does have to go to the bathroom or he may ring the bell to let you know that he has to go out. Just look for his signs that he gives you that tells you whether or not he has to go out when you ask him.
For example, my one dog when asked "to you have to go potty" will run to the door and back to me if she has to go out. If she does not, she will ignore it and act as she normally would. I wish you the best of luck with training!!!
