3vze code 52 troubleshooting
#21
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I do not know the 3.0 but Toyota does share a lot of the electronics operations from the 22re to the 3.0. If you can find the exact year of your truck in the bone yard, the injector harness is easy to swap on a 22re and cant see why it would not be easy on the 3.0.
The Injector Harness goes into the firewall just beside the wiper motor and it is easily unplugged from the computer and fished thru the firewall. You will need to remove your plenum and undo several other connections.
Just throwing another idea out there for you if all else fails. I am not much help on the 3.0 other then some basic issues.
The Injector Harness goes into the firewall just beside the wiper motor and it is easily unplugged from the computer and fished thru the firewall. You will need to remove your plenum and undo several other connections.
Just throwing another idea out there for you if all else fails. I am not much help on the 3.0 other then some basic issues.
#22
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... if you unplug the ecu, i get infinite resistance. Its my understanding that every circuit will have a path to ground (It has to or it will not work, the principle of electricty is based on this) and there for with have some level of continuity if the circuit includes a ground connection (Shield wire)
#23
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That's very close to what I get.
Not quite. The knock sensor generates an AC signal, so the it COULD be capacitively coupled at the ECU. In that case, you would measure "infinite" resistance looking into the ECU, because your ohmmeter is using DC. But that isn't the case here; both of us get a handful of kilo-ohms looking into the ECU.
Not quite. The knock sensor generates an AC signal, so the it COULD be capacitively coupled at the ECU. In that case, you would measure "infinite" resistance looking into the ECU, because your ohmmeter is using DC. But that isn't the case here; both of us get a handful of kilo-ohms looking into the ECU.
Thank you for help.
#24
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I'm pretty sure the knock sensor is just a piezo transducer. Piezo's have no DC continuity, so will measure infinite resistance with an ohm meter. They produce an AC signal, and are best modeled as an AC voltage source of about 500mV to 1V in series with a 10nF capacitor.
If you have an oscilloscope, you can watch the KS signal when you tap the block with a hammer. I don't know of any other way to really test whether or not the sensor is producing a signal.
If you have an oscilloscope, you can watch the KS signal when you tap the block with a hammer. I don't know of any other way to really test whether or not the sensor is producing a signal.
#25
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i would be interested in what the ecu reads on a meter with ohms and diode check, also what the good toyota knock sensor reads on ohm check. i do know that a reading of infinate is a bad sensor. think of it as a microphone. generally, a microphone is basically a tweeter, but instead of feeding it ac voltage, you read what it produces from the vibration. the knock sensor is similar, but different. if you have ever heard of the cheap peizo tweeters that work on "buzzing" when the signal is applied at high frequency, then you know how it wok=rks simiarly. the vibration in the peizo makes an ac signal, which is basically clarified by sending half the power through it and reading that as good zero power and the signal is the ac that comes from that bias voltage that is seen as "good zero" by the ecu. fyi, any sheilded wire over 5 watts should do great... a good source would be the 2-way (cb radio) coax. at 15 watts, cb cable is rather thin and flexable, thus easily used without problems you would find with rj6 tv cable stiffness. i have to say, your ocal dealership is garbage. try a reputable truck shop. in big rigs, it's common day practice to repair harnesses with factory or standardized connectors, as whole harnesses are only practical with warrenty repair and total loss, like engine fire. a good truck shop should have huge bins and all the specialized crimp tools to repair most factory harness plugs. i used to do it all the time. the worst being ford connectors, but i made stuff for that..... anyways, i'm rambling, so.....
in short, if you are reading nothing in resistance from the sensor, it is bad.
in short, if you are reading nothing in resistance from the sensor, it is bad.
#26
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Ok, after getting truck back from dealer, which the tech said there was a short in the KN signal wire, i did some more testing. if you test resistance between the 2 terminals with the ecu plugged in, you get 3.29 Kilo-Ohms, if you unplug the ecu, i get infinite resistance. Its my understanding that every circuit will have a path to ground (It has to or it will not work, the principle of electricty is based on this) and there for with have some level of continuity if the circuit includes a ground connection (Shield wire)
Does anyone know what the resistance should be be through the ks signal wire circuit with the ecu connected or can someone test their 94 3vze M/T 4x4 truck? Just unhooked the engine harness where it pluggs into the KS pigtail and run a OHM test between the 2 terminals with the key in the off position. Should take 5 minutes? this would really help me in determining my next step, ecu or KS. thank you.
Does anyone know what the resistance should be be through the ks signal wire circuit with the ecu connected or can someone test their 94 3vze M/T 4x4 truck? Just unhooked the engine harness where it pluggs into the KS pigtail and run a OHM test between the 2 terminals with the key in the off position. Should take 5 minutes? this would really help me in determining my next step, ecu or KS. thank you.
That's very close to what I get.
Not quite. The knock sensor generates an AC signal, so the it COULD be capacitively coupled at the ECU. In that case, you would measure "infinite" resistance looking into the ECU, because your ohmmeter is using DC. But that isn't the case here; both of us get a handful of kilo-ohms looking into the ECU.
Not quite. The knock sensor generates an AC signal, so the it COULD be capacitively coupled at the ECU. In that case, you would measure "infinite" resistance looking into the ECU, because your ohmmeter is using DC. But that isn't the case here; both of us get a handful of kilo-ohms looking into the ECU.
I'm pretty sure the knock sensor is just a piezo transducer. Piezo's have no DC continuity, so will measure infinite resistance with an ohm meter. They produce an AC signal, and are best modeled as an AC voltage source of about 500mV to 1V in series with a 10nF capacitor.
If you have an oscilloscope, you can watch the KS signal when you tap the block with a hammer. I don't know of any other way to really test whether or not the sensor is producing a signal.
If you have an oscilloscope, you can watch the KS signal when you tap the block with a hammer. I don't know of any other way to really test whether or not the sensor is producing a signal.
#27
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#28
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shunt is in the "sensor" for bias, just to clarify, not the ecu? it can be like 500k in some...... and it's less "era" and more "specific" engine...
#29
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There IS about 2.5k resistance looking into the ECU, but there isn't any (reasonably easy) way to tell if that is a bias network or just the input resistor. And it doesn't make any difference to me.
#30
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I have ordered a new OEM knock sensor and will replace it when it shows up to try and fix the code 52 that i am getting.
I was just thinking about my truck. My truck is a '94 but there is plenty of evidence that the motor had been replaced with a pre '92 engine along with the older engine wire harness as evident by the older style connector that plugs into the KS (KS has the round sensor connecter instead of the square connecter) pigtail. The engine also had the spring tensioner instead of the hydraulic type. When I was looking at ecms, my truck definitely has a '94 ecm.
Does anyone know if it is possible that running the pre '92 (early) wiring and KS with a '94 (later) ecm could possibly cause the code 52??
I was just thinking about my truck. My truck is a '94 but there is plenty of evidence that the motor had been replaced with a pre '92 engine along with the older engine wire harness as evident by the older style connector that plugs into the KS (KS has the round sensor connecter instead of the square connecter) pigtail. The engine also had the spring tensioner instead of the hydraulic type. When I was looking at ecms, my truck definitely has a '94 ecm.
Does anyone know if it is possible that running the pre '92 (early) wiring and KS with a '94 (later) ecm could possibly cause the code 52??
#31
I have ordered a new OEM knock sensor and will replace it when it shows up to try and fix the code 52 that i am getting.
I was just thinking about my truck. My truck is a '94 but there is plenty of evidence that the motor had been replaced with a pre '92 engine along with the older engine wire harness as evident by the older style connector that plugs into the KS (KS has the round sensor connecter instead of the square connecter) pigtail. The engine also had the spring tensioner instead of the hydraulic type. When I was looking at ecms, my truck definitely has a '94 ecm.
Does anyone know if it is possible that running the pre '92 (early) wiring and KS with a '94 (later) ecm could possibly cause the code 52??
I was just thinking about my truck. My truck is a '94 but there is plenty of evidence that the motor had been replaced with a pre '92 engine along with the older engine wire harness as evident by the older style connector that plugs into the KS (KS has the round sensor connecter instead of the square connecter) pigtail. The engine also had the spring tensioner instead of the hydraulic type. When I was looking at ecms, my truck definitely has a '94 ecm.
Does anyone know if it is possible that running the pre '92 (early) wiring and KS with a '94 (later) ecm could possibly cause the code 52??
#32
I struggled with this problem for a long time on my 4 runner. Replaced everything with new parts and still had the problem. I took my ECU to a friend who is an electrical guru....the guy that diagnoses electrical problems for rockets etc..... He tested the Capacitors that are on each circuit and found the one on the Knock sensor circuit was 30% out of spec, he replaced the capacitor and all the others also. He said anything that is 20 plus years old will eventually start failing. also replaced the electrolytics I believe is what he called them. To this day I have never had the problem again. We talked for awhile how most of the muscle cars and hot rods up to the 70's had very little electrical components. Today guys trying to keep vehicles running from the 80"s and 90"s are going to have to rebuild lots of electrical components. He had all the parts he needed on his work bench and said the parts he used didn't add up to 2 dollars.........
#33
Also I would check the wire going into the ECU with it running you should read some millivolts while it's running which told me that the Knock sensor was working, the signal was just not amplified enough for the ECU to process it. My hilljack terms not actual factory diagnosis procedures. I do remember it was a black wire on my ECU. But different ECU for auto and standard and years. I had a friend with a couple old ECU and they all had different plugs.
#34
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Ok, swapped out KS for an OEM one. took about 4 hours total, 1.25 hrs tear down and 2.75 going back together. I DID NOT have to remove timing belt to get the intake off so there is definitely time to be saved by not doing it. Use a pair of strong spring clamps to keep the belt from jumping a tooth on the cam gears when you remove the idler pulley.
I have about 200 miles on it and so far no more Code 52. Knock Sensor was bad, not the wiring or ECU.
I have about 200 miles on it and so far no more Code 52. Knock Sensor was bad, not the wiring or ECU.
#35
Yep. Another one.
Hey guys,
Ive got a 1993 4Runner with the 3vze engine (vzn series). Been reading literally every forum about this code. I’ve since bought a new sensor, pigtail wire and replaced the wire to the ecu.
Im now only getting Code 52 when the engine is cold. Once it reaches operating temperature I can switch it off, reset the code and turn it back on again and the code won’t reappear until I start it cold again.
Any thoughts??
Cheers
Ive got a 1993 4Runner with the 3vze engine (vzn series). Been reading literally every forum about this code. I’ve since bought a new sensor, pigtail wire and replaced the wire to the ecu.
Im now only getting Code 52 when the engine is cold. Once it reaches operating temperature I can switch it off, reset the code and turn it back on again and the code won’t reappear until I start it cold again.
Any thoughts??
Cheers
#36
Hey guys,
Ive got a 1993 4Runner with the 3vze engine (vzn series). Been reading literally every forum about this code. I’ve since bought a new sensor, pigtail wire and replaced the wire to the ecu.
Im now only getting Code 52 when the engine is cold. Once it reaches operating temperature I can switch it off, reset the code and turn it back on again and the code won’t reappear until I start it cold again.
Any thoughts??
Cheers
Ive got a 1993 4Runner with the 3vze engine (vzn series). Been reading literally every forum about this code. I’ve since bought a new sensor, pigtail wire and replaced the wire to the ecu.
Im now only getting Code 52 when the engine is cold. Once it reaches operating temperature I can switch it off, reset the code and turn it back on again and the code won’t reappear until I start it cold again.
Any thoughts??
Cheers
#37
Are you sure it’s code 52? Not to question your ability to count, but the way you describe it doesn’t sound like it’s code 52. The code is RPM specific. It shouldn’t matter the starting temperature. Even coming out of open loop from a cold start, the code should trip as soon as no signal is seen by the ECU at around 1600RPM. I guess if the connection were loose during cold starts for whatever reason, maybe?
I even disconnected the battery to clear all codes. (Rapid flashing of CEL upon test).
Then rev for about 30seconds (between 1500-2000) and CEL comes up Code 52. Let it warm up to operating temp. Turn off, turn on and won’t CEL light again.
Ive read on some of the code 52 forums that they had an issue with their MAF or Temp sensor In the MAF?
I understand that 52 indicates a bad sensor, wire or circuit so I’m confused as to why it can hear the knock sensor hot but not cold.?? I’ve also ruled out a loose connection. Everything is connected, and/or soldered etc.
can anyone confirm that 52 may indicate anything other than a bad circuit (sensor and ecu included). My next thoughts are trying a new ecu to see if that fixes the issue, otherwise I’m baffled.
Thanks again
#38
That's a new one to me. Maybe try to re-seat the pigtail harness and at the ECU harness end. Beyond that, I got nothing. Code 52 can only mean the ECU has not heard from the knock sensor in a specified range, so it's something between the knock sensor and the wiring all the way back to the signal pin at the ECU or the associated ground.
#39
Don't replace the meter until......
Yeah, the meter is a blue point i bought in '96-'98 and had to replace the leads. think the leads don't quite make good enough contact with the meter. Maybe it time to buy a new meter and test again. Do you know what i should see at the end of the engine harness at the knock sensor with the engine running?
#40
Code 52 when engine cold
thanks for getting back so quickly mholme.
I even disconnected the battery to clear all codes. (Rapid flashing of CEL upon test).
Then rev for about 30seconds (between 1500-2000) and CEL comes up Code 52. Let it warm up to operating temp. Turn off, turn on and won’t CEL light again.
Ive read on some of the code 52 forums that they had an issue with their MAF or Temp sensor In the MAF?
I understand that 52 indicates a bad sensor, wire or circuit so I’m confused as to why it can hear the knock sensor hot but not cold.?? I’ve also ruled out a loose connection. Everything is connected, and/or soldered etc.
can anyone confirm that 52 may indicate anything other than a bad circuit (sensor and ecu included). My next thoughts are trying a new ecu to see if that fixes the issue, otherwise I’m baffled.
Thanks again
Hey man, were you ever able to figure this out? If so could you share your solution?
I just got back from a mechanics shop who had one of these growing up, very knowledgeable. As soon as I started describing the engine cold vs engine warm situation w code 52 he started laughing and shaking his head in agreement. He said the 3vze blocks actually have a knock in them, small but enough to trip the sensor, when the engine is cold. It’s not until it warms up when it settles in that it won’t trip that code. He said you can grab brass fittings/ couplings from hardware store and insert that into the block, then the sensor into that and having that brass buffer is enough to stop the code