cracker_1

Had the dreaded code 52 as well in a 92 4rnr 3vze. Replaced the wire and KS from a "donor" motor I had. Probably a new record, it took me a little less than 3 hrs from start to finish to replace it all....

MW101

i replaced my knock sensor and sub harness, yet im still getting the code 52 and theres NO continuity from the sub harness to the knock sensor but there IS continuity somewhere between the ECU up to the sub harness connector, so my question is, is it easier to just do a bypass from the ECU to the sub harness rather then trying to locate the short curcuit

Blue_petersen77

Does anyone have pics of where the knock sensor wire comes off of the ecm? and/or where it leads? I really can't afford to do the whole job right now and the fuel economy is making it even more impossile (80 miles to and from work 6 days a week/ $40 a day!) to say the least! I just want to check for obvious damage around anything i can see without getting "kneedeep" since i'm short on time right now as well

93toyrunner2

Download FSM (link in my signature) - go to electrical, engine control, 3vze. Wire runs through the pass side main harness, up to the front engine plastic wire storage that runs from the pass side front of engine to drivers side front of engine, then runs down the drivers side along with the injector wires for that side. If you are going to replace the wire (easiest way to bypass old wiring that is brittle), use the coax cable and a good solder gun as mentioned above.

hypermax

im goin to do this on my 90 3vze but im wondering where you would get a plug that goes into the knock sensor? i can get a KS off of ebay for 17$ but i cant find any plugs would any toyota knock sensor plug fit? like one from a 22-re and i can just wire it into the sub harness from mine

Punchy

Rarely does the KS go bad, But the pigtail do.
Sometimes the micro coax as well.
The dealer has the pigtail and cheap too, I think I paid $8 (was amazed).
22RE, Easy to fix.
3VZ, Moderate diffaculty but requires more parts and time.

gone4x4en

I just made a bracket out of 2x2 angle ¼ inch iron, drilled 2 holes for mounting, tapped 12 x 1.25 hole for knock sensor mounted it on the back drivers side on the head. After fixing wires extending them both wiring harness and sensor ends 1 foot each side. Tested buried in engine one did not work, tested spare one in mounted bracket WORKS GREAT. Just to GET ME OUT OF THE WOODS!!! After reading post about Knock sensors I will fix buried in engine one when I get time. Thank YOU for the posts about by passing it and the detailed info on vibration waves. Pig tail bad also useally what wrong is very true, dealer $20 California

zchead

I know it's an old thread but I'll be relocating my knock sensor this week. Thanks guys

dr1553

Did it work for you? My 91 has a bad cylinder and the dreaded code 52. I'm tying to decide if it's worth the cost of a head job. I would hate to have the heads done and then still have code 52. I also don't want to replace the $200 knock sensor just because, but also don't want to not replace it when in there if it is infact bad.

So relocating a KS to the engine lift hook with the new $10 wire from Toyota sounds like a really good idea as a way to test it out.

I'm even thinking of using the $30 KS from a '97 S10 4cylinder. It has been reported to work for some ppl. If it destroys my engine so what, the way I look at it it's already to that point. If it works and stops the code 52 then I'll know to do it right, with an OEM KS and new wire when I have the heads pulled.

zchead

Unfortunately I came down with pneumonia right after tearing mine down to do the ks move. As soon as I'm back up and get it done I'll let you know. Also I found an oem knock sensor on eBay for $25 instead of the $200. But if you don't like that option go to a napa. They have an echlin brand, which is pretty good, for around $100

dr1553

Hope you get feeling better soon man, that's no fun!

I've read thread after thread with ppl saying the fake toyota sensors don't work. Plus they are still really expensive. May sound illogical but I'm going to try the Chevy sensor. This way we'll have another documented case on the forum. I'll report what happens either way.

I'm just trying to decide if I'm going to cut the original wire going under the intake or order a new one and cut it. The Chevy sensor has to be spliced in somehow. If I cut the wire there's no going back without pulling the intake to replace the wire, but I think it's at that point already anyways. On the other hand if the wire is bad I might splice into the bad section and the repair attempt will fail anyways even if the Chevy sensor will work. Bla.

thechief86

I did a chevy sensor, and a new chevy plug, and spliced it into the original pigtail that plugs into the harness going to the ecu. (I split the coax and grounded one wire and plugged the other into the sensor ) I still have a code 52, but I didn't realize people were mounting their sensors on the plug itself, so I screwed a brass plumbing adapter into one of the bolt holes on my head (for the hook), and then screwed the sensor into that. Now I'm thinking I should drill and tap the hook itself, and perhaps my s10 sensor was bad out of the box?
My 4runner is running halfway decent, and I've driven it about 900 miles since I replaced the head gaskets and this code popped up. I'll get around to trying it again next time I have a day off.

91 4runner: 3vze, 5 speed, 4.56 gears and 32's, stock.

scope103

The coax is grounded ONLY at the ECU. Not at any of the connectors, not at the knock sensor.

I know there are LOTS of people trying to relocate their knock sensor, and every now and then someone pipes up and says "mine worked!" But I just don't believe it. Why would Toyota bury the knock sensor all the way in the heart of the engine, when it would work perfectly well dangling from a lifting hook?

But more power to you and Good Luck. Let us know your experience.

dr1553

I had to go do some reading about what the purpose of coax cable is. So the ground is just a shield, to keep the good signal in and other garbage interference out. Basically.

So is there a good chance that most of these code 52 could be from a break down of the shielding in the main wire itself? Not the signal wire? Looks like most ppl fix the problem by replacing the KS and the short wire, but not all. I guess the most likely place for the shielding to break down is in the short wire. But it could be anywhere between the KS and the ECM.

So my ground at the plug under the TB tested good, no resistance, and the signal wire tested good back to the ECM, just a tiny deflection off zero on my meter......but that doesn't mean the shielding isn't compromised somewhere along the way. It could still be grounded even if it had a split somewhere that didn't go all the way around, but a big enough split to let interference in.

Is that all correct?

Then about the shielding....it looks like it ends an inch or so from the KS, looking at pics of the short harness you can see where it goes to single wire. Then what about the plug itself? Isn't that another place where the shielding is not wrapped around the wire and could be letting in bad signal?

Then where does the shielding end and go to ground on the ECM end? I just had my kick panel off and it's single wire into the ECM so it ended somewhere before I could see it.

When people run a new coax all the way from the ECM to the KS, where are they grounding it?

Could you just cut it back and ground it anywhere under there near the ECM? Splice in the new center signal wire to the wire going into the ECM? Then at the other end how do they get it connected to the plug at the end of the harness? I'm guessing at the KS end you don't need to worry about grounding the shielding, just let it dead end near the plug?

I agree with you on this.....but I think relocating a new KS is a good way to verify that a new KS and wire is going to fix code 52 before tearing all the way into the engine and sill having the code.

If the code means the ECM is not hearing the KS and that's it, then relocating it should work, correct? Unless code 52 can be thrown by not only a no signal, but by the wrong signal. Then relocating the KS wouldn't work because of that....unless it can properly "hear" the engine thru the lift hook.

thechief86

So far these last few posts are getting really close to being the most helpful knock sensor thread I've found yet.
Scope, the more I mess with this, the more I am starting to agree with you that the only way to fix the code 52 is to take the intake off and replace everything with genuine toyota parts. But I had to try the "easy" fix forst, because I've already spent a ton of money getting the head gaskets and all of that stuff sorted out.
I am going to keep trying to get the light to go off this way for now, and if I can't, I will do it right.
If that still doesn't work, then I'll park it until I can afford to swap in a chevy v8, because screw it, why not?

zchead

Toyota buries this sensor deep under the intake because that where it works best. This sensor is designed to detect "knock". SO the closer it is to the cylinders the quicker and more reliable the signal is from it.
As for moving it people do this including my self so next time it goes bad its easier to fix. If you take care of your engine and use quality gas there is normally no concern for a knock.

zchead

Do you really believe the sensor can tell a difference if its "listening" to a hook or an engine?

thechief86

If you've had success with this, will you please post some pictures and explain how your wiring from the sensor to the harness is done? I had no luck grounding the braided part of the wire and connecting the single wire to a chevy s10 4 cylinder sensor.
I don't care if the sensor works properly, I just want the light off and my driveability back.
I run premium gas and do regular maintenance on all of my vehicles. If the engine runs another 6 months, I can afford to replace it it I have to.

scope103

Perhaps you don't understand the purpose of the knock sensor. In the "old days" the engine was designed and the timing specified so that it was always 5-30° retarded from the "optimal" timing. This assured that the engine would (almost) never knock, but the efficiency and performance were impaired.

Modern engines (including the 20-30 year old ones here) recover that performance by always adjusting the timing so that it is as advanced as it can be. How? The ECU advances the timing until the engine just starts to knock, then backs it off until the knocking stops. Many times per second.

If the ECU can no longer "hear" the knock sensor (because of a bad wire, too much interference, knock sensor dangling from a lifting hook, ...), it would be adjusting timing blind, and the result of that is a hole in a piston. So to save the engine, it dramatically retards timing, and throws code 52.

NONE of this has anything to do with the quality of gas or other things we worried about in the '40s. If you are trying to "stop" the engine from knocking, you are addressing the wrong thing.

thechief86

I use premium fuel for the extra detergent content, as well as the availability of non-ethanol fuel in Tennessee. From the research I've done on the timing and knock sensor function on these trucks, it only advances or retards the timing within 10° of where it is set at idle by whoever messed with the distributor last. I also know from previous experience with many types of engines, both efi and carb'd with manual adjustability on everything, that you will only experience engine damage like you speak of when pinging is obvious. This is only.my experience in the last 10 years or so, so I'm sure there are exceptions.
Have you seen a 3vze with a relocated knock sensor and holy pistons yet? Not trying to be a smart butt, but I am also aware that this is the Internet, where people often repeat what they've heard, and not their own experience.
But yeah, I don't want to pull my intake off right now, because I just had it off at thanksgiving, and it's a pain in the arse. Might as well just get my gm v8 conversion kit ordered....