Ok here's the long and short of it:

-89 3vze 205k miles
-code 52 shows up.
-check wire, though it has just been replaced.
-check timing when hitting engine with hammer, no change observed
-add some grounds.
-check the wire at the ecu.
-code 52 still here.

So I decide to take the plunge and tear it apart and replace the sensor. I get a sensor from a junkyard and test it. When I get the old sensor out, it responds the same. Good news. I test continuity in the wire running to hte ecu. It ranges from 5kohm to 30mohm. Can't tell you why. If install either sensor and tap on the engine, I get no response from the sensor. Mind you the engine is still torn up and I've just got an ohmmeter between the sensor terminal and ground. I saw in a supra forum that people tend to want to replace the wire because it's susceptible to radio interference. I dunno. I'm stumped. I'd like to get some advice while I have the whole thing torn up, and lord knows I don't want to do that again any time soon.

Any help would be much appreciated, since I look a lot like this guy right now >>

 

You may want to try cleaning the terminals inside the connector where it come up out of the block under the throtle body.The terminals seem to be made out of brass and will turn green with tarnish over time.I had the same problem with the pesky code 52 for a year and a half before I tried this.Have not seen the code in 7 months.Use a small piece of sandpaper folded backwards on a small screwdriver to get in there.Worked for me!

 

Also you want to look at the harness end.Not the end that goes down to the sensor..I believe its an orange plug.Just look for the green tarnished brass terminals in there.Good luck.Please repost if this works for you.

 

I have an 89 3VZE, 154000miles and have had the knock code 5-2 showing up off and on for 4 1/2 years. Is it just me or does everybody else notice that the 52 code is there all winter and then goes away in the early spring? I called a Toyota tech and he says that if you throw a 52 code it is because you have an open condition in the knock sensor circuitry. I bought a new throttle body gasket, so when the light comes back on I am going to get to the connector located under the throttle body and thoroughly clean the contacts, apply a dielectric grease and see if the fault is at that connector. Obviously my knock sensor isn't bad because it is working now, but my advice to you is if you have your truck completely apart (which looks like a pain), I would invest the money, buy a NEW sensor and the 8" wiring harness load the contacts up with dielectric grease and call it good. Those sensors are sensitive.

 

Good news everybody! After replacing the sensor and the wire the whole way from the sensor to the computer, the problem still persists. Man, do I ever hate this engine. It worked correctly for less than 24 hours since I've owned it. That's pretty sweet. It's a good thing that most everything is inaccessible, and problems defy logic and repairs. If anyone thinks he can change my mind, they can feel free to come over to my house and make this code 52 go away. I dare you.

End rant.

 

Did you try resetting the ECU?

 

I had the battery disconnected for 5 days while the engine was in pieces. Does that count?

 

Ouch man, I had the same thing happen on my old truck when I replaced the engine. It got to the point where I had replaced every thing and it still did it so I said screw it, I left it and now my bro has the truck with 20,000 miles on the new engine and it doesn't even show the code any more.