cluster issues

i am either getting 4mpg or my fuel gauge does not work, i fill it up and the gauge goes to near FULL then 2 3 days later it drops very fast to 1/4 then near E also my odometer digital bulb is dark does show mileage but unreadable and air bag with seat belt red light in upper left corner never goes away.....

What year?

How much fuel are you adding to get it from 1/4 to full? You may have a fuel leak. It could be the fuel level sending unit or a related wire, a somewhat common problem on GM vehicles. Easiest way to check is with a scan tool that shows the fuel level sensor voltage. You can also check at the connector with a voltmeter.

The odometer backlight, I believe, is an LED which is soldered to the board. You'll have to remove the cluster and take a look. Some places will repair them.

For the seatbelt light, try jumping the wires at the sensor under the seat, might have a bad sensor.

Hi i had old original cluster with no tach and installed aftermarket sony stereo then had cluster odometer light bulb went out and fuel gauge is not accurate. i went and bought a 2004 Malibu RDS CD/Cassette radio deck and paid the local dealer 240 they used Tech 2 scanner for 2 minutes to unlock it. had all wiring checked, changed cluster to a 2004 cavalier with a tach and now the fuel gauge is bending backward hitting the temp gauge. need advice please help checked all fuses