HP LaserJet 5100tn - Tray 3 not recognized

[BRMIL]

I have an HP Laserjet 5100tn that doesn't recognize Tray 3 as being installed.  The tray was working the past.  If I remove all the paper from Tray 2 and try and print, it just asks me to put paper in Tray 2 even if Tray 3 is full.

When I print a config page from the printer, it only list Tray 2 under "Paper Trays and Options".  

I went into Print Management > Properities > Device Settings and changed Tray 3 from "Not Installed" to "Installed" and the "Form to Tray Assignment" from "Not Available" to "Letter".  Tray 3 still doesn't apear on the config page and still isn't detected. 

What would be the best way to test this Tray to see if it's not connecting or just broken?

[davidzuts · Accepted solution]

If not showing up on the config page then the printer is not seeing it as attached. If you remove the base unit from the tray there will be a connector that fits into the bottom of the base unit on the tray. Check to make sure it is not broken. If necessary google the service manual which will show you the connector's location and the connection to the dc controller of the main unit where you may be able to trace the leads to make sure they are fully connected. Odds are the added tray has gone bad where the circut board that communicates with the main unit has gone bad.