I have a 05 trailblazer lt, runs fine but every light in the dash is on, new fuel pump, gas gage still doesn't work

Angela, every light lit is usually the ignition switch, doubt it's stepper motors especially if it's all of them.

Could be the stepper motor in the instrument cluster . GM instrument cluster had bad stepper motors . 2003 to 2006
How to repair GM Instrument Cluster Speedometer Gauge Stepper

Every light lit on the instrument cluster , could be data network problem . Do you know what a serial data network is , class 2 or GMLAN ? Hooking up a professional or factory scan tool to view sensor data to ECM - engine computer .
Fuel Gage
The instrument panel cluster (IPC) displays the fuel level as determined by the engine control module (ECM). The IPC receives a serial data message from the ECM indicating the fuel level percent. The fuel gage defaults to empty if:
• The ECM detects a malfunction in the fuel level sensor circuit.
• The IPC detects a loss of serial data communications with the ECM.
When the fuel level is less than a pre-determined value, the IPC illuminates the low fuel indicator.