I would read through the knock sensor sticky in the 1st Gen forum and you'll find lots of info on the KC cable.

 

I'm usually on my phone looking at this forum. Where do I find said sticky? I must be overlooking it?

 

the signal wire for the knock sensor is almost always shielded, on any vehicle, from sensor plug to ECU plug. its it not a ground

 

Technically the shielding of a shielded wire is a ground wire (this is what shields it), it just isn't part of the sensor circuit. If you look at the wiring diagram for any shielded sensor signal wire in the FSM, it always shows the shielding being grounded to a chassis ground point, usually near the ECU.

So in the case of this particular knock sensor:
-This is a single wire sensor. The knock sensor itself is what creates voltage; it is a piezoelectric element, which basically means it generates voltage when you shake it. The ECU does not supply power to this sensor, it only looks for voltage FROM this sensor.
-Even though it is a single wire sensor, the sub harness plug is two pins. The white wire is the sensor signal wire (pin 2). The other pin is to pass the wire shielding through the harness connector. This is because the shielding is grounded near the ECU.
-Please refer to the screenshot from a 240sx (also KA24DE, sorry...this is what I have handy on this computer. Sensor wiring is the same on the truck, but connector/pin locations will be different on the truck). The dashed line cylinder represents the signal wire shield. It grounds near the ECU but is not part of the sensor circuit. You also get a nice visual of how this shield passes through the sub harness connector as well.

The wiringspecialties replacement sub harness will work just fine. It's "upgraded" because they just use a more modern harness sheathing vs the factory brittle split loom.

 

Excellent, KAtheworld! Had no idea we would be discussing electrical engineering. Hope everyone's ECMs are happy. I have contacted Wiring Specialties and they have assured me that their knock sensor sub harness is shielded. They have the afore mentioned part number as being a replacement for a '98 Frontier. I just received my order and the sensor connector is an exact match. However, the connector to the main engine harness does not match mine. Picture shows mine (right) and the WRS-S13KA-KNK (left). Apparently, I need Part # WRS-S14SR-KNK (S14/S15 SR20DET) as listed for a 240 (KA24DE). Wiring Specialties needs to update their website. Very good customer service, though. The harness is well made with the exception of it having thinner gauge wire than OEM (18 vs 14?). I will definitely have to reinforce the single wire to the sensor to keep it from breaking. Other connectors that I have viewed (Rock Auto, Amazon, etc.) show the specific grooves on the wrong sides (mirrored). Amazon does list this particular harness (cheaper BTW) and their picture shows the correct groove orientation. And now, time for carbon cleaning the EGR intake manifold ports and replacing the cracked exhaust manifold.

 

Excellent, KAtheworld! Had no idea we would be discussing electrical engineering. Hope everyone's ECMs are happy. I have contacted Wiring Specialties and they have assured me that their knock sensor sub harness is shielded. They have the afore mentioned part number as being a replacement for a '98 Frontier. I just received my order and the sensor connector is an exact match. However, the connector to the main engine harness does not match mine. Picture shows mine (right) and the WRS-S13KA-KNK (left). Apparently, I need Part # WRS-S14SR-KNK (S14/S15 SR20DET) as listed for a 240 (KA24DE). Wiring Specialties needs to update their website.

I swear I didn't use any of my engineering degree to figure this stuff out, it's simply just spelled out completely in the factory service manuals. I'm mostly just copying and pasting from there.

Interesting that the Frontier uses a different harness connector than the 240sx/Altima, but I'm not all that surprised. Nissan is terrible at standardizing things.

Often times, you can simply de-pin the connector that is wrong and swap it for your old one. It's usually just a matter of pulling a lock tab out of the wire side of the connector (there isn't always a lock tab, but it's usually a horseshoe shaped piece of plastic that is a different color from the connector body), then depressing a clip under the pin inside the connector (sometimes from the wire side, but usually from the pin side), and the wire/pin/seal will pull right out the back. A small dental pick is my favorite tool for de-pinning connectors. Provided the pins are the same shape and size between connectors, you can just slide them into the other connector until you feel them click into place.