1JZ-GTE Fault Code 52

[rogue-vl]

Hi , I am getting Error code 52 Knock Sensor Signal , returns after clearing the ECU, isn't triggered by free reving the engine (in neutral) but as soon as the car is in motion the fault light comes on. Doesn't seem to be effecting the performance at all. Caps in the ECU have been replaced, and both knock sensor plugs are connected.

How do I fault fine this further.

Engine is out of 91 JZZ30, no modifications to engine and all factory wiring intact

[midnight_purple_GA70]

maybe try swapping with some known good knock sensors... could be a faulty one?

not sure what test could be done on the current sensors themselves exactly...

sure there isnt something causing knock while driving not necessarily from the motor but something in surrounding areas...

[CrUZida]

Whilst not common on 1JZ motors, its common on other ones for the knock sensor wire to breakdown.
You may need to change it.

The code requires a few things to happen before it will be thrown. Can't remember exactly, but its something like vehicle speed to be able 20kph and RPM to be above 2000 before it will register. Hence it doesn't happen free revving.

[George]

try first disconnecting the sensors and see if the error pops at free revving. This way you will differentiate broken wire from everything else. Modern Toyota knock sensors have built-in resistors to indicate that their wiring is alive, don't know if older ones have them though.

With vvti 1jz's there's quite common knock sensor fault that is not indicated by the ECU but makes the car undriveable (too lazy). If you don't note any performance changes I think the sensors work ok most of the time.

[rogue-vl]

I disconnected the 2nd (rear ) sensor and it didn't throw any codes free revving. any suggestions on other testing methods, or for that matter how to access the sensor with 1/2 dismantling the engine or having an extra joint inserted in my arm?

[shadowR]

The knock wire is shielded, so if it is old it may not be doing its job properly.

As stated change that.