Hey y'all
I've been tracking code 52 for a bit on my project runner. (1990 3vz auto 4x4)
Some history on it.
I had the engine redone at a local machine shop.
Right from the machine shop I put a new NGK knock sensor in it along with a new pigtail
I also replaced all ignition components and fuel injectors, I've put around 2500 miles on it and decided to park it because this code.

I've tried 2 different engine harnesses (original & replacement)
I've also tried a second ECU
And I replaced the knock sensor with a working genuine Toyota knock sensor out of a donor 3vze because I was getting no voltage from the NGK sensor during testing.

I tested the wire harness for continuaty at the connector & at the ECU both good.
I tested and got voltage off the harness connection.
I tested sensor voltage verification of voltage along with voltage increase when I tap on the engine. Sensor seems to be working.

The FSM targets these 3 components as the problem to code 52 so I'm a bit confused on what can be the issue here.

About to try the hook relocation as a last resort.

(Another idea I have is I've noticed my injectors tick pretty loud referenced as injector tick. I've read that excessive noise may cause issues with the sensor)
*I'll check my timing again soon also*

Hoping someone can throw me a bone here.
Thanks for the read


Today's tear down

 

Toyota 3vze code 52 is no signal from knock sensor. Thoroughly recheck the pigtail for that for a bad connection. Beyond that check the pins and connector pads on the ECM for dirt, corrosion, etc. That could be causing the "disconnect".

 

Here's something I can't readily explain.
Back when we were doing the 3vze headgasket recalls around the clock we had issues early on with the knock sensor. Toyota initially didn't include them in the approved parts list. If we did straight head gaskets and left the knock sensor unplugged for a short time we rarely had issues. But if we had to deck the block, resulting in the sensor being left unplugged for several days, it almost always threw a code 52.
One of my more insightful techs discovered if he removed the knock sensor and plugged into the hanging wire harness while the block was getting decked it didn't set codes.
Eventually Toyota included the sensor and pigtail in the recall, rendering it moot.
But those sensors are THAT sensitive. And prior to the 3vze, engine knock sensors were never a concern on any other vehicle.

 

All very useful info; Thank you.
I'll look into testing the knock sensor wiring further including the ECM side of things and see what I find.
I'll update my diagnosis once I have completed my tests; so this may help anyone else.

 

You must use a Toyota knock sensor. Not ngk. Put a factory one in mine. No more issue.