2008 saturn astra gauge cluster not lighting up and code U0073

[1.8astra]

hello saturn community, i recently purchased a 2008 saturn astra xr with a 1.8L and automatic transmission. the car runs and drives perfectly but it’s having some electrical problems. i noticed my gauge cluster was not lighting up when driving at night. i checked the dimmer switch and nothing happened when i turned the knob. also checked the actual headlight switch to see if my headlights were on. i put the knob in the automatic, off and on position again nothing happened. doesn’t matter what position i put the headlight switch in the headlights stay on even in the off position. i’ve replaced the headlights switch again same issue. i noticed a green light was on below the rpm gauge, the light is a headlamps sign with a line crossed through it. in the owners manual it says this sign is for “exterior lamps off reminder”. that sign is a reminder that the headlights are off, but my headlights are stuck on even during the daytime. i also checked the fuse for the cluster and it’s not blown. what really surprised me was when i turn the ignition off and pull the key out the gauge cluster lights up and turns off automatically after time. the cluster lights up and gets power but not while the car is running. also the obd scanner is showing code u0073 “control module communication bus off”. i have no idea what this code could be. in conclusion the gauge cluster won’t light up when the cars running. the exterior lamps off reminder sign is on but the headlights are stuck in the on position. the headlight switch does not work, and can’t control the headlights. and code u0073 is showing up. any help would be much appreciated thank you