Knock Sensor Testing | Toyota/Lexus | Tech Tip
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- เผยแพร่เมื่อ 30 ก.ย. 2024
- If you are turning imports away because your techs lack the training and expertise to diagnose and repair these vehicles, then you are missing out on a significant portion of the repair market. Dave Scaler from the Mechanics Education Association (MEA) can help you take on tough problems on the most popular imports on the road today.
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This video was made back in 2009. Many of these vehicles are now older and at higher mileages and knock sensor codes are a regular thing. Recent history tells us that most of the time its not the knock sensors. Instead its the short wiring harness going between the knock sensors and the main wiring harness. The heat down in the engine valley eventually damages the shielding on the harness and this is what trips the codes.
As stated in the video, on a Toyota or Lexus V-6 its a lot of work to get to where the knock sensors are located down in the engine valley. So if you are going to dig your way down in there its best to change the wiring harness, both knock sensors and the short bypass hose. Its important to only use original equipment OEM knock sensors and harness made by Toyota. Many of the aftermarket parts are substandard and they will cause the codes to come back again. You can buy OEM parts on eBay but be sure they are Toyota parts and not knock offs. Be sure they are still in the original Toyota bags that the bags are still sealed shut. I just recently bought two Toyota knock sensors for $23 a pair and a Toyota harness for $36. They were installed and the engine was put together again. That was weeks ago and the codes have not come back. Its worth it to change all 4 components down in the engine valley so you won't ever have to do the entire job again.
Finally, just in case its a good idea to check the new sensors and the wiring harness before you put the intake manifold back on. Connect the ohmmeter to the end of the knock sensor harness that plugs into the main wiring harness. Note that the connector has 4 pins but only 2 of them carry the signal. The other two pins are for the shields, which aren't connected to anything. Then ground the negative lead of the ohmmeter. Then tap the cylinder head and see if A/C voltage comes out of the harness connector. If it does you are good. Don't worry about the frequency response of the sensors. They are brand new and they will work just fine.
Your not listening for a knock at "7000 times a second", but a knock at a frequency of 7kHz, just to clarify. And introducing a loud sound at 7khz will most likely not trip it because the sensor is "listening" to the resonance in the block, not the ambient air surrounding the motor. If that was the case, every thumping bass system would be retarding the ignition. Now if you could put the voice coil right on the block, then you would register AC.
no
you need to lean the mixture not to remove gas completely
disconnecting one injector will you make see a single cylinder misfire code ,not more
On a mass peizo system The noise outside resonant frequency is usually filtered inide the ECM input circuit. It would have a bandpass filter tuned to 7Khz or whatever is the natural resonance of the engine. The resonant frequency of the engine varies by its mass and material and shape. Probably not by much maybe in the range of 5-9Khz. Most noise and vibration from other parts are lower amplitude than actual knock vibration. I think the put the tuning in the sensor to make the ECM circuit simpler but also makes it hard for DIY people to test so required to goto the dealer. But thats just my hunch. Think about it sensor is physically tuned to 7Khz center frequency makes cheaper to manufacture the ECM... More profit. Knocking or hammering on block should cause the block to "ring" or vibrate at its natural resonance like tapping the side of a wine glass or a wind chime. Although its so dense and heavy you don't really notice it or hear it the way a bell rings its going to resonate. NASA supposedly did a ring test on the moon during the lunar landings to determine the resonance of the moon and to calculate its mass amd density and likely internal shape and material...
Your honesty and tenacity is very appreciated.. I applaude you sir..
Best regards from Finland.
man oh man.. toyota reliability?
Got it! :O) I don't think you could have done a better job @ learning me up! I was new to this info... now it's going on my resume (there is still some room on the Post-It-Note). Thanks for the video!
Some of us know how tasty certain year Toyota knock sensor wires are to rodents, lol
2slofouru seriously I don't get it lol same with the Acura mdx and rdx I've seen a few of those chewed up too
Do you think that setting valves incorrectly this could cause the knock sensor to go?
Very informative, thank you. Would like to see more videos like this.
great information and techniques.
I recon to test the later version of the knock sensor to put a loud speaker on the motor and use a laptop to generate a 7khz sound. Probably safer then forcing the motor to ping.
great video but how can I get my engine (ls430 like in the video) to ping to test the knock sensor when the entire inlet is off the engine ? it wouldn't b a small step to put it all back together....
question: the knock sensor produce it own voltaje but what is standard voltage? I have a kia sportage and the manual say the ks proces average voltage is 2v - 3v AC and other ks other brand only 750mv o lower, anda how onw what is thea real voltage for to know if is the bad o good ?
Knock sensor works ;)
Your engine has a bad knock : /
Hey mir gefällt das richtig gut was du da machst. Mach genau so weiter! I like :) Daniel
Thank you, i do have this problem i will be doing this test.
thank you - very good information :)
WELL DONE!!!
Hello Sir .
Most tests on th Internet say you should expect to see a 2.5 voltage at the sensor connector , while the sensor is plugged in and the ignition key is turned on ., and a 5 volt when the sensor is disconnected ......
Does this apply to Toyota cars ?.......It does NOT seem to be the case . Some people say Toyota sensor work differently ....!
good video
great video
I have a yaris supercharger 2004 and the check light is on and the car have no boost, the computer says knock sensor and i dont know if the sensor is bad? Or something with the fuel pump, fuel filter? Tell me what to do please!!
great video!!
i replaced my 1994 gmc 350 motor with a 1980's motor.well my harness doesnt have a plug to plug into.what can i do im lost please help me.
Hello friend that I write to thank you for uploading videos and aprobechar important to ask a question:
I have a 2003 nissan frontier v6 does not serve the detonation sensor I want to change but I can not locate where I could say is that I have heard that this sensor under the intake manifold but I removed the distributor can not see anything so I ask guidance. now let me thank you for the infformacion you can ofreserme.
greetings.
As the instructor states “When changing the knock sensor change the short jumper wire from the knock sensor to upper harness”
Toyota in their service info. add replace PCM to the above. Start testing the PCM pin by pin only after wire is replaced and if you still have a problem.
can you tell me where a knock sensor is on a 02 highlander also would it not go into overdrive if it is bad
i know the sensor is fine, its the wiring under the steering wheel, i just have no clue what wires or anything. fml.
hi i have a 96 maxima and i have a missfire on all my ignition coils,will the knock sensor cause that?thanks
Take phone, downloaded frequency generator, connect speakers, profit.
what about placing sensor near computer speaker which generates 7kHz sound?
7000hz can't be achieved with a hammer an extension...use an air hammer! Hahaha. Just Kidding don't do that.
Hector Vargas that 7Khz is the natural resonance of the engine block when it is smacked hard. Like a wine glass or guitar string it can vibrate at its natural freq... It varies by the block shape mass density and material but probably not by much.
Please send us a hd service manual picture
When did they come out with the Resonance Piezo Electric knock sensors?
can we check a knock sensor by connecting it to a engine?? externally. can someone please help?
Could you use a small impact and a socket on a bolt?
very good explanation ,what is the maximum mv should produce the knock sensor ?
x2 for example i have a kia sportage 2.0 year 2011 and his Ks on manual service say the normal or average is 2 at 3v but in other brand like this video say 750mv no understand why
Does disconnecting an INJECTOR work ?
good vid
U over detail boody
Kim
Can a sensor be bypassed.?
When he found a break in between cars our on-site mechanic replied, "Does the engine have a Knock, What type of vehicle, and whats the mileage on the vehicle, Make Model Engine? Cant be bypassed but there are alternatives and risk that accompany those decisions."
I hope that helps, for more information please go to aviondemand.com
podrias interceptar los cables que van al sensor cortarlos intalar otro par de cables y instalar uno nuevo arriba del manifold , eso hize yo con my nissan frontier y nunca he tenido ningun problema.
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