Hello I will help you with your question,
The wire to the knock sensor could be open or the connector to the sensor. It also could be that the wire is shorted to ground.
The procedure to troubleshoot this code is below, it would be helpful if you had a scantool that would allow you to see the knock sensor signal. You could see if there is any activity on the signal and that would check the wire. Otherwise you need to check the integrity of the wire and the connections with a volt/ohmeter
Click here for procedure
Let me know how I can help you
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
Yes a shop should be able to find the cause in less than an hours labor.
If you want to see if you can get a scanner that can see it I will be happy to provide what help I can, just let me know.