6 yr. old dog - is too late to potty train

We adopted our dog Charlie when she was 7 mos. old as a rescue. We surmise that she was kept in an apartment during the day and probably never walked and thus pottied in the house on newspapers. She is a 62 lb. pit bull, extremely sweet and friendly without a hint of aggression in all the years we've had her. Consequently, we have tried out best to accommodate her. Part of the problem when we attempted to make her go outside is that she would not go until we brought her back to the house and never right away. Another problem is timing. She pees and poos sometimes at 2:00 and 3:00 in morning. Why is that? Any suggestions? I'm used to her going to the basement on mats but now that it is difficult for her to go to the basement due to surgery, perhaps we can teach an old dog new tricks.

Welcome,
you have been very patient with Charlie. I adopted an unhouse trained chihuahua and it made it easier that she only did tiny wees and poos. I dread to think how bad it must be with a large dog,

Do you have your own yard ? Does Charlie ever go to the toilet on a walk ? Will she go to the toilet in front of you or does she leave the room and toilet else where?

Apart from the habit of going indoors, a lot of dogs prefer certain surfaces to go on and also some aren't confident enough to go to the toilet in thr big wide world and wait until they are home.
I dont know why she goes at those times, it could be to do with her meal times .

I think you can still train her to go outdoors, it will just be harder because she has so many years of experience going in the house. I would ask the same questions asked above. Will she ever go outside while on a leash? And do you have somewhere in the house you can put her when you can't supervise where she won't go potty? Like a bathroom or bedroom?

If so, I would start taking her out often on a leash and rewarding her for going potty outside. Then, while she is indoors, either keep her on a leash and near you or put her in a small part of the house when you can't supervise, an area where she is unlikely to go to the bathroom.

I don't know why she is going at 3 in the morning either. Is this normal behavior for her or something she just started after her surgery? If it's a new behavior, I'm wondering if she's trying to hold it since she can't get to her usual spot in the basement?

You might have to either crate her or have her leash tied to you if she does not go outside and try again in say about 10 minutes, go back outside until she goes. There needs to be no way she can be unsupervised until she goes outside or you may never be able to housetrain your dog.

Where does she sleep at night and hat time do you feed her?