Another Knock Sensor Thread

Joined
Mar 4, 2015
Messages
149
I used this: 1JZ/2JZ Knock Sensor Connector
And this: Repair Wire, 090-II Terminal

to repair my broken knock sensor harness on my 94. Worked perfectly.
That's what I'll be going with then. I haven't had a chance to test anything yet because of work but I took it out on my lunch break and the light didn't come on. On my way home I got all the way to the grocery store which is about a 15 minute drive and the light came on. I definitely have it narrowed down to operating temperature so I'm guessing that it is in the wiring being that it's so close to the motor.
 

bloc

SILVER Star
Joined
Sep 19, 2008
Messages
4,866
Location
Central Texas
 
 
I don't know enough about the Denso engine management system to say for sure, but it is possible that it may not be looking for the knock sensor signal until certain parameters are met.. like coolant temp.

Alternately, it may not be throwing the CEL until it sees a good knock signal on the rear sensor but something that doesn't make sense on the front sensor.. all of which may not happen til the engine hits operating temp.

So my point is that it may not actually be the heat from the engine doing anything funny with the wire itself.. the wire may be bad at all times, but the engine doesn't know it until some other condition is present, which only happens at operating temp.

Side note.. it isn't too difficult to get to the ECU behind the glove box. You could use a continuity meter between the front and rear KS plugs on the block and the ecu plugs to try and diagnose things before you go cutting up your harness.

In my case I had no CEL.. at some point in the past someone must have broken a KS plug and just used a crappy parts store crimp terminal directly onto the sensor. Amazingly it still worked, but was far from water and dirt tight.
 

westafari

Sand Cruiser
Joined
Aug 25, 2014
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212
Location
Roanoke, VA
That's what I'll be going with then. I haven't had a chance to test anything yet because of work but I took it out on my lunch break and the light didn't come on. On my way home I got all the way to the grocery store which is about a 15 minute drive and the light came on. I definitely have it narrowed down to operating temperature so I'm guessing that it is in the wiring being that it's so close to the motor.
That's very similar to what mine was doing. I could take very short trips without the code popping up. I think it also has something to do with the RPMs, as in once you go over 2000-2500 and the sensor isn't reading the code will pop.
 
Joined
Aug 26, 2013
Messages
104
Location
DFW, TX
Last year I had one bad sensor, throwing up a CEL light. I needed to get it "legal" in a hurry so I spliced the good one into both of the wires that feed into the ECU, and this solved the CEL light. This reminds me that I need to revisit the issue again to actually fix it. It may be worth it if all you need to do is pass inspection or something as I did.
 
Joined
Mar 4, 2015
Messages
149
since you mention code 52, I assume you have either a 93 or 94? 95-97 have a different code for knock sensor (325 and 330) if I recall. In any case, I would look closely at the wiring harness, in particular where it wraps around behind the EGR at the back of the head. That EGR gets real hot and the wiring is way too close to it.
So I finally found some time to tinker with the wiring harness. I followed the wire loom of this knock sensor bank into the biggest wire loom where I lose sight of its direction. Does this wire go up the big loom through the intake plenum and around the EGR, across the firewall into the cabin? I even checked the plugs that go down and around of the block and there isn't any corrosion or exposed wires from what I can see. The color of wire of the knock appears to be a solid white with no tracer. Is this correct?
 
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