Dear ced
Welcome to the forum. Please see this link (
Regressed Behaviors in Traumatized Children | The Attachment Trauma Center Institute (ATCI) ) that I think has a very good explanation of this kind of behavior by traumatized children. I recognize you didn't ask for this but rather for an intervention that will help your child urinate in the toilet, a behavior I am assuming he did learn but no longer can relied upon to do, all of the time.
As I read this article I see that the peeing in wrong places happens because the traumatized child has regressed, and the reoccurence seems to happen when the child is emotionally triggered in a way that reminds him of the traumatizing event. I would think that a tranquil, secure, low stimulation environment, with loving and predictable attention and support, would be an environment that would help a child feel safe and secure, to minimize regressive triggering. Maybe a new puppy, who needs to be housebroken would be a way to reinforce habits indirectly so as to not shame your child, who I am sure does not choose to do this in a conscious way. But I think the main intervention should be psychological or psychiatric treatment, or even neurofeedback which I am learning is an effective treatment for trauma, for children and adults. Also equine assisted therapy often helps traumatized children. If you have a facility near you, it is often free for children who are disabled, have special needs, or a history of trauma.
I don't think your child does this for reasons that are within his conscious control and therefore I don't think that continuing to talk with him about it will have an effect. He has regressed because he is triggered and he is triggered because he has been traumatized. Trauma in children affects the brain. He doesn't choose to do this or want to do it. I suggest that you see a pediatrician, a counselor, an expressive arts therapist, etc. and they might be able to help deal with resolving the trauma itself.
I have put down my thoughts. Others will be here in the morning.