2006 buick rainer obd code30 - 2006 Chevrolet Trailblazer

http://www.fixya.com/search/p693632-buick_2005_rainier/wont_shift_3rd_gear

Autoparts will kno

Does this have digital/electronic controls ?

run fault codes
indicates an electronic problem with an overheating component
possible ECM ( check using a known good unit as a replacement), crank/ cam position sensor

chk fuel pressure and fuel regulator or spark plugs worn

On the internet ---pictures you need

Google it

On this website you find fuse box diagram and description for Buick Rainer (2004)

http://www.carknowledge.info/buick-rainer-2003-2006-fuse-box-diagram

This is likely caused by a defective main headlight switch in the dash control panel, the wiring harness to the switch is likely burnt as well and it will need to be replaced, The replacement connector can be purchased at the GM dealer. Never install a new switch if the connector is heat damaged the new switch will burn out very quickly. Also do not use crimp connectors to install the repair wiring connector, solder it and use heat shrink tubing.

Take the car to auto zone and have them pull the trouble codes. Post the codes and we can go from there. Codes are stored in the computer to tell tale on which system is failing. There are many things it can be. Is the gas cap tight? This is a common problem that people overlook

Have you checked the transmission fluid level?