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Discussion Starter #1
So as I stated in a previous thread, I need to buy new axles and new motor mounts. I came to this conclusion with your assistance. the recap is vibration while idling which concluded the need for the new motor mounts. And shake and vibration while driving which concluded axles.(plus i'm able to grab axles from under car and move axles way too much.


so my question is this. I drove car yesterday and check engine light came on. pulled code 52. knock sensor would the vibration and shaking be enough to cause that code?


Thanks for the advice and thoughts. respectfully, Richard Carson
 

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Token Aussie
1998 AE102, 2018 ZRE182
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so my question is this. I drove car yesterday and check engine light came on. pulled code 52. knock sensor would the vibration and shaking be enough to cause that code?
Knock sensors measure frequencies that are in the kilohertz range, any engine-bay vibrations will be dominant in engine rpm range is a whole order of magnitude lower.
 

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1997 Corolla
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The computer will detect a short or open circuit in the knock sensor circuit. A loose knock sensor can also cause the code. Maybe the vibrations rattled it loose, so check that it's secure in the block.
 
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Senior TN Member
Porsche
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Knock sensor is a solid-state device, so it's very durable and rarely fails. As RollaDad mentioned, it's most likely wiring and/or connector.

1. Disconnect plug from knock-sensor and measure resistance of sensor between its terminals

2. Inspect plug closely. Verify metal sockets inside are intact and not overly corroded. Verify wiring going to sockets at back of plug isn't frayed or broken. Wiggle it and tug a little to be sure. Then plug back onto knock-sensor.

3. Measure knock-sensor resistance at ECU connector (unplug from ECU first). This measurement should be exactly the same as what you measured at sensor itself. If not, the wiring or plug is bad.
 

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Discussion Starter #6
yearning for knowledge

thank you all for your thoughts. I have found through all my years of repairing my own vehicles, that I .indeed can repair most things on my vehicles,. what I have trouble doing is finding out the why that part failed. even though a part may fail I always try and find what pointed to the failing of that part.


ie: my vibration at idle , after much research pointed to mounts. particularly the right mount. I did replace and the vibration was gone. it is now since returned as it was an aftermarket one.
so with this knock sensor, I have learned about it and realize it come on when motor is pinging or when the rods, pins, pistons are making some noise. the problem I have is the vehicles power is there. when I hit the accelerator, with meaning, the vehicle responds . I also have never heard this vehicle ping ever.
I am not all of knowledge when it comes to figuring these thing out. so I will check the harness, the resistance as outlined above. I am wondering if that harness if corroded causes the code, can someone explain why that happens.
I just want to have the knowledge for the next time I run across knock sensors. thanks a lot. respectfully, Richard Carson
 

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1994 Corolla DX
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You are thinking about the knock sensor code incorrectly. The code is not thrown to indicate a knock is present. The code is thrown to indicate there is an error. Verbatim from the factory service manual for code 52: "Open or short in knock sensor circuit with engine speed between 1,200 rpm and 6,000 rpm".

If a knock is detected a code is not thrown. Rather it is used as a cue for the engine computer to adjust timing such that knocking no longer occurs.
 

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Token Aussie
1998 AE102, 2018 ZRE182
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You are thinking about the knock sensor code incorrectly. The code is not thrown to indicate a knock is present. The code is thrown to indicate there is an error. Verbatim from the factory service manual for code 52: "Open or short in knock sensor circuit with engine speed between 1,200 rpm and 6,000 rpm".

If a knock is detected a code is not thrown. Rather it is used as a cue for the engine computer to adjust timing such that knocking no longer occurs.
^This. The knock sensor is actually detecting knock all the time, that is how it knows to adjust the timing. The computer advances timing until the sensor begins to detect knock, then retards slightly so that the knock goes away (much like how you measure blood pressure) - this is constantly happening whilst the engine is in closed-loop cruise mode.
 

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If you are indeed hearing pinging, then knock-detection system is not working correctly (hence code 52). Test sensor and wiring to determine where's fault.
 

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Just play along....
corolla
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Knock sensor is a solid-state device, so it's very durable and rarely fails.
Rarely fails, yes. Durable? Well maybe not. On my car the connector broke apart when I was taking the connector off to remove the engine.

I'll warn you that the Chinese one available from a popular Chinese website was WAY cheaper than one from the parts store but the one I got failed in months. I got another one from the junkyard and its caused me no more trouble.

Hint: it is removable with a large socket from the bottom of the car. Its screwed into the back of the block below the intake manifold.

-SP
 

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Discussion Starter #11
I disconnected plug from sensor, following this from DannoXYZ 1. Disconnect plug from knock-sensor and measure resistance of sensor between its terminals. upon inspecting fount the sensor to have only one terminal. so how do I measure the resistance between its terminals if there is only one. thanks in advance. respectfully Richard Carson
 

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1994 Corolla DX
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The body is the "second terminal" as it's a ground connection.

So one test pin on the connector pin and the other on the metal body of it.

Resistance should be 1Mohm or higher.
 

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Discussion Starter #13
ok rolla I have this sensor off vehicle sitting in front of me. im going to put one lead to pin and other lead to the body. what setting do I set the tester on. my tester on the ohm scae starts at 200 and goes up to2000k? thanks for the help
 

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Set the ohmmeter to 2000k. That will measure up to 2M Ohm.

1M Ohm = 1,000k Ohm = 1,000,000 Ohms
 
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Yes, looks like a bad sensor.

On ohmmeters, sometimes on the lowest scale you can never get 0 even just touching the probes together. I'll get 0.2 or 0.3 on mine, but in reality it should be 0.

What matters is the 0 on the 2000k scale.
 
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It shouldn't be a problem. Left unplugged the computer will not advance the ignition timing as much as usual, so you will have less power and get worse gas mileage.
 
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