JSON Post with Customized HTTPHeader Field

I have inherited some code that will eventually be part of an API call. Based on the existing code, the call is a post to retrieve JSON code with an access_token. While this would normally be simple and like every other API out there, this code requires that there be a customized httpheader field for the client secret.

I was able to make this work in Objective C with URLRequest, etc. but now that I am creating the call for a web component, I have been roadblocked.

I am using a pretty standard jquery post

        $.post('https://url.com', 
        {access_token:'XXXXXXXXXXXXXXXXXXX',
         function(data){
           console.info(data);
         }, 'json');

With a HTTP-EQUIV in the header. But the post never retrieves data and the server itself doesn't recognized that any call was made (even an incomplete one).

I may have to scrap this code and start over, but if anyone has encountered this problem before, please offer any insight.