You need a home-made code checker like the one I built. It's a simple matter to plug into the diagnostic port under the hood and pull codes from there.

Be aware that close assist doesn't come from the same pump as the door/lumbar/headrest/park assist.... pump - it's a separate unit in the trunk wedged up next to the gas tank on the driver's side.

If you've got closing assist issues - check out this link - it's VERY informative: http://www.v12uberalles.com/Closing_Assist_Pump.htm

This link, on the same sight describes how to pull codes: http://www.v12uberalles.com/pulling_codes.htm - the article has a link to the site where you can get the schematic for the code checker gizmo. The only thing I did different was to buy an LED from Radio Shack that is ready for 12v operation with a built in resistor and properly indicated positive and negative leads - makes the assembly a little easier. If you have more questions about my version, just send me a private message.