bob hennig

code 52 is set when the computer fails to see KS signal generation. When the KS is working properly, it won't set code 52 because it recognizes a small or large detonation problem, which is its job. It retards the timing 10 degrees and will continue to moniter for detonation. After the rebuild process, I wonder if we are not changing the detonation cycle or frequency Hrz, and the sensor for the 3.0L needs to be a wide range type to be able to detect signal change. The reason I say is I have been moving timing around and find if base timing is advanced to 20 degrees, I can hold off code setting until 4th gear around 2500 rpm. Maybe signal can not be seen because of sensor range? May answer location move problem, along with some EMF problems. Either way, I have replaced all the copmponants of the system, minus the ECU and still see the problem, but I can control its set point by timing advance, which would create earlier detonation for sensing at 7HZ range. What think? I posted another thread yesterday with a little more info. Bob

Arkman

QUESTION? I had code 52 come on and there was no way possible for me to fix it anytime soon, so now every time i fill my tank up i just add octane booster and that code hasnt been back since. Works for me anyway.

YotaFreakTN

this is the exact point that has been being made, and yet it seems to be falling onto blind eyes or deaf ears.

shaeff, good try and all. however, some people have a stainless craniums.

shaeff

Yeah, that goes straight back to my original point- electrical noise disrupting the signal in the wire. Chasing our tails much? Any interferance with the wiring will cause code 52 if the shielding does't ground it out. I never argued that it didn't! If it's interrupting the signal, then guess what? Your wiring is bad!

I have never encountered a code 52 problem I haven't been able to fix. Ever. I've been doing it for about seven years, and have cured the problem for well over one hundred people. I'm not sure what you're doing wrong here.

No, that's because while the FSM might not be the end all of repair procedures, it just so happens that in regards to code 52 it IS the end all.

I know it listens for 7khz. Never argued that. Detonation will not cause the code dude. Get over it. Explain why, then, that Supra guys blow their motors due to detonation, yet NEVER, EVER get code 52? I know why, it's because code 52 isn't there to tell you that your motor is detonating. It's there to tell you that there's a problem with your knock sensor, wiring, or ECU. (a point that you even proved yourself with your quote from that Toyota Avalon article. )

When the knock sensor detects knock, it will retard the timing, but not set the CEL. Read that article again, and this time try to comprehend what's written.

Had to quote this separately- your red and blue statements here are contradictory. Want to think about that and try again? Frequency will not cause the code 52 unless there is no frequency at all (in which case a dead sensor, back to my initial argument) a ground issue will if it interferes with the signal wire. (Which again, goes straight back to my first post. ECU, wiring, or KS itself.) You're not helping your non-existent cause a whole lot here.

Agreed, been saying that the whole time.

If by faulty equipment, you mean the KS is dead, the signal wire is grounding out, or the ECU is dead, then what have you been trying to argue this entire time, as that was my point from my very first post? If you're stating that electrical interference on the wiring will cause code 52, yeah, I have been saying that the entire time too. So, I'll ask you your very own question:

Your point is what?

You keep telling me "prove it Shaeff", yet I have seen ZERO actual proof from you. All you keep doing is trying to shoot my FACTS down with your hearsay, and tell me I'm wrong, when anybody with a half a brain can tell that your argument is quickly falling to pieces with every post. Read over the tech articles I posted above. If there were outside variables are NOT listed in the FSM, don't you think that those variables would be listed in the Technician training pages? I mean, come on dude, that book I posted scans of were used BY TOYOTA to train their techs! They don't leave anything for guesswork when writing those books.

Bob, you've got it, however doing a headgasket job won't effect this. The MKIII Supra is plagued by blown headgaskets from the factory (just as bad as the 3vze) and all those headgasket jobs don't effect the knock sensors one bit. As I stated above, I've helped rid code 52 from well over a hundred people's Supras, and never had the problem come back. It really is as simple a system as it looks.

Aside from that, it doesn't matter what frequency the detonation occurs at, because getting detonation won't cause code 52, which you said yourself.

I would doublecheck your wiring, Bob, test it very well. If you can find someone with an ocilloscope, have them test your knock sensor for proper function.

Octane booster does pretty much nothing, especially if you're actually trying to fend off detonation. It raises the octane rating like a tenth of a point. Where in the NE are you? I'd love to fix your code 52 for you, so you can see how it's supposed to be done. Besides, detonation has nothing to do with code 52.

-Shaeff (who's getting blue in the face)

bob hennig

I am in the Hastings area. I have replaced the sensor, the pigtail, and the wiring with shielded coax cable. Not the ECU yet. Like I said I have been able to control when the code is set, at what RPM and gear by timing advance so I was thinking that the sensor and wiring must be getting some signal to the computer depending on the timing and where knock occurrs. Bob I am checking with a buddy now to see if we have access to oscilliscope. B

bob hennig

shaeff, I agree the lack of a knock sensor signal is the cause of code 52 set, not detonation. But I was wondering if this code seems to be so prevelant after overhaul and all parts are replaced, could the code be set because the KS is not seeing the detonation occurring, in other words there is no detonation to set sensor into action. Could this be an advance problem in distributor, an enriching function which is overfueling thus causing over rich, lack of knock signal in normal rpm ranges. I hope to see the signal at the computer harness soon with a scope. I love this thread!!! we're woorken here!! Bob

shaeff

My apologies, I meant Arkman- his locations says Northeast. I'm in NY, so noplace near you! It's likely not the ECU that's giving you issues. I would doublecheck the wiring. If the sensor is bad, you will get the code as well. I'm interested to see what happens when hooked to the o-scope.

Well, in a perfect world, you won't detonate at all, however, if the KS isn't picking up any signal at all (really, outputting the signal) then you will get code 52. The overfueling issue is due to the timing retard that the ECU does when it sets code 52. It's a byproduct, not a cause. Have you checked your signal wire for continuity to ground? There should be none.

I never claimed to be above average intelligence, but I do understand the workings of the KS circuit. (If you were complimenting me, then thank you.) Even if the tech articles aren't gospel, in the case of THIS problem, they are. I'm fully willing to debate, but Flecker isn't being fair with it. I have posted numerous FACTS about this system, he has posted NONE.

Simply because he fixed HIS code 52 with some odd "out of the box" thinking, doesn't make him correct, or make it the proper way to do it. Again, I've never had a code 52 beat me. Not once.

I'm not sure exactly what people's problems are. I can't rewire their truck from over the internet. I can't properly diagnose it over the 'net either. I do know, that if someone brought their vehicle to me with a code 52, that it would leave my house with no codes.

If Flecker has figured some special way to fix the problem that does NOT involve the ways I repeatedly post, I'm very interested to hear it. Even if I don't agree with how it's done, I'd certainly love to toss it around in my head for a bit.

By the way, if I come across as rude or condescending, that is not my intent.

bob hennig

shaeff, I replaced sensor and pigtail with new one from Toyota, I rewired to ECU from pigtail by, cutting off plug from harness to pigtail and running new coax cable to ecu and connecting directly to computer plug by splicing to short pigtail at ecu. I disconnected wire from sensor and ecu and checked continuity thru sensor circuit, no resistance good connections, and checked for ground to engine, body. No ground on sensor wire. Then I grounded the shielding to ecu bolt in body and at pigtail plug again good continuity thru shielding to ground, no continuity between shielding and sensor sire. When I hooked the wire harness up to computer, I do get a reading then between the sensor wire and ground, showing some resistance thru the computer. I asumed this was normal as the ECU has resistance circuits for functions. Was not sure what it should be, or should it show an open, no resistance? Bob

bob hennig

I am leaning more and more to a change of frequency in the knock signal which is causing the code 52. I am not sure that the knock sensor is reading any knock because it doesn't exist in the frequency range in lower RPM of engine. The base timing advance to 22 degrees and hard accelleration will hold off code set until I back off throtle to cruise at about 2500 RPM. I can hold off code set indefinately by foot feed position. could it be that the older sensor design is too narrow a band for modern metals, gaskets, compression ratios, ethanol. From the toyota info, it says the ks responds to hertz signal of knock, large knock 7 hz, high signal, small knock, lower htz, small signal. It says that when the sensor detects no knock, the ecu slowely advances the timing until knock occurrs. Quest, the code 52 is set after the ECU detects no signal from the KS after 6 revolutions. So I assume the Distributer spark advance thru computer must move relitively rapidly to cause the new knock to occurr to get a signal generation, otherwise 6 rev would pass and set code 52 as the ks would not be generating any MA's to tell the computer it has a knock to protect against. I talked to my machinest today and he had some of the same questions about this sensor and was suggesting if there was a more sensitive KS available. Is the 22R motor a different frequency sensor or a wide band sensor. This 4 runner runs too good right now after rebuild so I can not wait to get this resolved and see it then! I am willing to experiment a little. Maybe all these rebuild problems occurr on the v6 as it seems that that is where the great majority of issues occurr. The existing sensor and circuit must be getting a signal to the computer to hold off the code set is all i can think. It will set the code once I go to light throttle. No signal at all, IE grounded signal wire, EMF interference, bad ks, bad ecu should set code consistantly.

bksr5

Ok I've read and re-read this entire thread. Tell me if I'm close to getting this or not.
Seems clear that there is confusion between what causes knock and what causes a code 52. I agree that you don't get a code 52 from your engine knocking. The knock sensor is a piezoelectric device. It is not a variable resistor, it creates a voltage. The ECU can detect if there is a short or an open connection to the knock sensor because it sees no voltage. The code is not thrown because of knock, just the opposite, it's because it senses no vibration at all. Seems like the first thing to do is read the voltage at the knock sensor with the engine running. Anybody know what is should be?

If it is reading the correct voltage then move on to the wiring. Zero resistance in the wire end to end, and max resistance from signal wire to ground. Also I heard that you usually ground a shield at only one end to prevent ground loops-important in high frequency circuits.

If you really want to fudge the circuit then you could supply the correct voltage through a resister from 12+ to the ECU (I would not do this-fix it)

Am I close? Flame suit on.

Bob K

bob hennig

I will remove ground at engine and ground near ECU only instead of two areas and try it. I agree, code 52 is set when no knock signal is sensed. Question is with problem being set after rebuild of engine, which seems to be complaint of many and with replacing all the parts involved and still no fix, have we changed something so that knock can not be seen with this particular ks, have we altered the frequency? Not sure yet, just know I can control when the light sets by hard accel and advancing the timing to 22 degrees. If I set the timing at factory spoec of 10degrees, code 52 sets almost immediately upon accelleration in 1st gear. I can hold it off until 4 or 5th gear by getting into foot. Still searching clues!!!

bksr5

It definitely is on a long block swap. I think we need to break down the problem into two categories. Those with a permanent code 52, and those who can clear it, but after awhile it comes back. The first group might be the lucky one. Fix the wiring or swap out the KS and your good to go. The second group is going to be much tougher. The KS must be putting out the right voltage at idle or easy driving, but something is going on for the ECU to lose signal from the KS during more dynamic driving. Is it really the KS or is it weak wiring that has temporary open circuit? I think I will try to monitor the KS with a volt meter while driving and see what I see. I'm afraid things might happen too quickly to really monitor though. Also can try a continuity test on the wiring while driving. That should be easier to see. What do you think?

Bob K

bob hennig

Its the part throttle condition, light throttle when the code sets. I am trying to use an oscilliscope to test for wave signal. Not sure about voltage test, I think only sends milliamp signal. Not sure. The continuity test can be conducted w/o running vehicle, disconnect from pigtail and computer and use ohm meter to test continuity and resistance. Good continuity on sensor wire and no resistance, no continuity bet sensor and ground shielding wird. ground shield no resistance to ground, good continuity. Bob

bksr5

I was re-reading the Service Training Info under the KS Notes #3. Very curious. It says if the KS is disconnected (on purpose or by bad connection) while the engine is under heavy load or maintaining high speed for 1 or 2 minutes, it throws a code.
Heavy load is explained later as vacuum under 200 mmHg. But what is high speed. High RPM or are they actually using the speedo input. And if neither of these conditions occur and you disconnect the KS it won't throw a code??
We really need to know what the heck the ECU is actually looking at when it decides to throw a code.
We know it is looking at the amplitude of the output of the KS to decide if and how much to retard the timing. Since it doesn't throw a code when you first start up maybe it's only looking at continuity of the circuit as whether to throw a code. But if this is true it should throw a code when you disconnect the KS while running no matter what the engine is doing-just idling, under load, or running at high speed.
I have a volt meter, an oscilloscope, and an audio frequency generator, and will be trying different tests tomorrow. Will report any useful findings.

Bob K

bob hennig

If I disconnect the ks at comp or at pigtail, it will set code 52, no signal to ECu. It won't set code on idle as the circuit checks for signal above 1200 or 1800 RPM, (depending on what book read), clear to 5500rPM. No signal in 6 revolutions of crank, bang, code set. Let me know what you find out. Thanks, Bob

bksr5

OK dumb question. I know you can't get to the KS w/o removing the intake manifold, but can you get to the other end of the pigtail w/o tearing things apart? There's so much crap around the intake manifold that I don't know if I'm just not seeing it or there's nothing to see. Thanks.

Bob K

トヨタ Hilux

on my 22re I can easily reach the ks through the passenger wheel well..

bksr5

OK-thanks to the info from Bob H I finally figured out how to get at the KS pigtail. I removed the throttle body so I could get my fingers on it. You can just barely get at the connector from the pigtail to the main harness. The other end of the pigtail dives into the valley-no view, no access. I wiggled the connector and I pressed it together as best I could and reattached the throttle body.
A/C on and mashed the gas pedal a few times. No code. I could always get this to trip the code before. Looking good-went for a spin. Slow acceleration with load, hard acceleration without down shifting, hard acceleration with down shifting, just regular driving, NO code.
So either 1) Something in the pigtail was not right. Either bad connection or marginal wire that I got conducting again. KS seems to be OK. 2) Just a lucky coincidence. We'll see with more driving.
Gave up doing any readings or testing. Afraid if I disconnected the pigtail I might have a hard time getting it back together without further disassembly. Basically, quit while your ahead. If a code 52 pops up again, then I'll bite the bullet and do some testing figuring I'll have to have the intake ripped off anyway to put on a new pigtail.
Not the best engine design I've ever seen. Thanks for all the input from the forum. What a great asset when your trying to keep an old truck running without paying the dealer a fortune every time something goes wrong.

Bob K

bksr5

OK final update.

Drove ok for a few days, then threw code 52 again. Had a new pigtail and KS installed and all seems well. We'll see but very promising.
Took the old parts and ran some tests. First, the pigtail was very brittle and cracked with the shielding showing thru in some places but still seemed to be conducting ok. The pigtail is a shielded wire with the signal wire going to the KS pin and the shield floating at the KS but grounded thru the harness. The return ground for the KS is provided by the engine block. The pin on the KS very fairly cruddy and might have been the problem all along. I put the KS in a vise and wired it up to a scope and a multimeter. At rest there is infinite resistance at the KS so just checking it with an ohm meter isn't going to tell you anything. I ran my electric screw gun with a locked chuck to create a constant vibration and held it against the KS. It then put out about 300 millivolts and showed a resistance in the 10 M ohm range. Put out a nice signal to the scope set in AC and slow sweep. Also, just hitting it with a hammer does put out a spike in AC volts.
Hopefully this will help people diagnose KS problems.
I talked to the tech who really seemed to know his stuff and he confirmed that the code 52 only tells you that the KS circuit is not functioning properly.
Knocking (or anything else) does not set code 52. So as stated before in this thread, its the KS, the pigtail, harness, or ECU. I would say almost never the ECU. More likely the pigtail, but check for corrosion at the knock sensor. Also from my testing, I'd be surprised if the torque on the KS would make much difference. If way too loose, sure, too tight you might break it, but anything in between should be fine.
Sorry for the rambling, but this has been a real PITA, and maybe this will help someone else solve their problem.

Bob K

Korey

My pigtail was replaced two years ago when the head gaskets were placed and the code came up a couple of months after the replacement... What the HECK?