The Brown? (should be blue) and Red should both be ground and the Black is the signal from the sensor.
The computer sends the signal (in your case 2.54 volts) and the knock sensor modifies the signal as it produces voltage. The 2.54 volts from the computer is how the computer checks the integrity of the wire.
It sounds like you have everything present, I would check the shield and the red wires to ground while applying voltage through a resistor to be sure it has real ground present, If you use a 100K resistor and put battery voltage to the wire through the resistor and measure on the wire side of the resistor you should not see voltage as it should all drop across the resistor.
You really need a scantool that shows the Knock signal, if the signal is present then you either have a knock (you may not hear/feel it) or you have a failed computer.
There are no TSBs for the knock sensor other than a warning to install with a torque wrench to 15 - 18 ft lbs or risk damage to the sensor.
I know this is hard to chase without a scanner and it is just as hard to do with one sometimes. Check the ground on the red and shield wires and let me know if those come back good. If you have not tightened the connection yet try that also.
Let me know how I can help you with this