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Have you lost spark and fuel pressure?
The gauges don't all read properly in your case though because the fuel gauge isn't working.
Not seeing a bus message in the cluster isn't an indication that the PCM is working.
Disconnecting the battery has very little chance of changing anything, but you can try it. It just takes a minute. There's no need to leave the key on or anything like that, and you don't want to have the key on any time a battery is disconnected or reconnected. Just turn the key off and disconnect it for a few seconds and then reconnect it.
Checking to see if the PCM is awake involves using a scan tool to see if it will communicate.
Things that will cause the PCM to not wake up are a loss of power or ground, a short to ground on the 5 reference circuits, and a short to voltage on the sensor ground circuit.