My 96 3.0 is showing code 31. Anyone know what this is?

It's a failure in the EVAP system purge solenoid circuit. A few minutes after you start you should hear the purge solenoid make a noticeable repetative click. If it's not then either the wiring or connection are bad or the Powertrain Control Module (PCM - engine computer), isn't turning it on. You can read all about it here: http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1a/41/ab/0900823d801a41ab.jsp Click on diagrams to enlarge.

Hey RIP thanks for the great info. I had just installed a new fuel pump when this light came on. I disconnected the battery, reconnected, now everything is happy. Praise the Lord!!