gas gauge temp gauge auto headlights door locks do not work on 2002 Saturn L100

This problem started about three weeks ago with the car not starting. I unbolted the positive battery cable waited a second and reconnected it. Then the gas gauge and temp gauge would bounce from empty to full or cold to hot. Now they just do not work. The ABS light stays on. The security light stays on as well as the check engine light

Asked by for the 2002 Saturn L100
It is not good to only disconnect your battery positive cable, one should always disconnect the negative cable to prevent any voltage spikes to any of the sensitive electronics on this vehicle. I hope that you did not spike a module, but by the sound of your symptoms, you accidentally may have done so. I would have a good shop inspect this issue at this point:

here are some shops: