I have found a few limitations so far that hopefully can be worked around with a bit of advice:
It uses POST rather than GET. When I click to Authorize within EasyMorph it seems to send a GET request as the error returned is “The requested resource does not support http method ‘GET’.”.
It uses ‘Password Grant’ OAuth Grant Type. In a different API connector I have to pass the Client Id, Username and Password but in EasyMorph I can only see an option to pass the Client Id.
I was unable to find any documentation regarding this service. But, as of now, EasyMorph does not support password grant type / resource owner password flow.
Actually, it looks like you don't need full-blown OAuth at all in this case. You can use Web Request action to make first POST request to the oauth/token endpoint, then use Return response body as action result option, parse received body as JSON and pick access_token field. I can't find any documentation regarding this Telematics service, but if this is in some way compliant with OAuth, you then should use the value of this access token in subsequent actions.