Node template.tpl.php for custom view mode?
You need theme_hook_suggestions.

    /**
     * Implements hook_preprocess_node().
    */
    function MYMODULE_preprocess_node(&amp;$vars) {

      if ($vars['type'] != 'product_display'){
         return;
      }

      if($vars['view_mode'] == 'product_list'){

        $vars['theme_hook_suggestions'][] =  'node__' . $vars['type'] . '__' . $vars['view_mode'];
      }

  } 


Now you will be able to use: node--product_display--product_list.tpl.php

Make sure you have to change MYMODULE.

If you want to use it from template php then use following code. I also assume you use zen theme:

function template_preprocess_node(&amp;$variables) {
 if ($variables['type'] == 'product_display' &amp;&amp; $variables['view_mode'] == 'product_list'){
// looks for node--node_type--view_mode.tpl.php in your theme directory
   $variables['theme_hook_suggestions'][] =  'node__' . $variables['type'] . '__' . $variables['view_mode'];
 }
}