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Code 41/52 Together
I've searched and searched but still can't seem to figure this thing out. Hopefully you guys can point me in the right direction.
91' 3VZE automatic with a newly (less than 200 miles) rebuilt engine. I pulled/installed the engine myself, so I have become pretty familiar with it. The previous owner installed a new TPS, but it was not adjusted properly and was causing the transmission to shift awkwardly. There were no codes triggered at that time. I went in and tried to adjust it while on the truck, and ended up pointing it the opposite direction (the first time it was facing all the way down, now it was all the way up). Shifted better after a few miles threw codes 41/52 and went into a SEVERE limp mode in which I could barely do 25mph. Got it back to the house, pulled the TPS, adjusted it on the bench according to the specs in the FSM. Reinstalled, reset timing to 12 degrees BTDC and drove it. It was giving me a code 52 after warmed up and driven for about 20 minutes. Sometimes it would only trigger when I revved it in park. Fiddled with the timing some more and drove it to work today, then it hit me with 41/52 again. The power was down, but nothing like the first time it triggered. I was still able to drive on the highway, it just shifted wierd. I checked the timing last night when it went into the bad limp mode, and it was at 8 degrees ATDC, so no wonder it drove like crap. Sometimes the codes make it go into limp mode, other times they don't. What gives? I've read for weeks about fixing this code 52, so I am wondering if mine is behaving like other trucks with the same code. Does it usually come on right away, or randomly like mine? The codes seemed to have started once I adjusted the TPS incorrectly the first time, but that may just be a coincidence. I am also getting like 9mpg if that info helps. It seems to run great though. Sorry for the novel, I just want to make sure I gave all the info I had! *EDIT* I should mention that the KS and pigtail are brand new OEM. |
What do codes 41 and 52 mean? (Yes, I can look them up, but I don't have every code memorized. Help yourself by helping your reader.)
Code 41 says you have an open or short in the VTA part of the TPS. http://web.archive.org/web/201211190...85diagnosi.pdf It has (almost) nothing to do with adjusting it; either the TPS has an open/shorted spot, or more likely, you have damaged wire. By the way, following the FSM to adjust the IDL contact on the TPS is doing it the hard way - especially on the 3vze with the connector pointing away from you. Instead, use the brains of your transmission to tell you what IT thinks the TPS is doing. http://web.archive.org/web/201211190...85diagnosi.pdf http://web.archive.org/web/201408160...34electron.pdf (AT-128) If you did any searching, you know that code 52 means that the ECM "hasn't heard" from the knock sensor after you've been driving a bit. (at my last count, there are 1.42 bazillion threads on this code) No, it has nothing to do with the TPS. It has a little to do with the knock sensor, but 99% due to a wiring issue. The most likely place is the "pigtail" from the sensor to just outside the intake manifold. If that wasn't replaced when the engine was rebuilt, stop, back up, and do it. Checking the timing "during" code 52 doesn't help you much (8 v 10 would make only a small difference). When you step on the gas, the timing advances a lot, by design. Code 52 prevents that more than anything. |
I knew that the code 52 meant the ECU had no communication from the sensor, but I wasn't sure if the TPS had anything to do with it. Thanks for the resources and clarification. That diagnostic info helps a ton and should point me in the right direction. Since the pigtail is new, I most likely have issues in the main harness somewhere..which will be super fun to track down.
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If I go about running a new wire from the KS to the ECU, would the instructions in the link below be valid? I've never messed with shielded wire before. I am also pretty sure mine is only a 1 wire sensor.
http://clintsgarage.blogspot.com/201...ck-sensor.html |
Uh, maybe.
You do need shielded wire, and RG58 ("cable tv wire") might work. (RG58 is for RF signals, and has a characteristic impedance of 50 ohms. I have no idea what characteristics the stock knock sensor wire has.) It's also really easy to find; there's probably 10ft of it in your apartment dumpster right now. It is fat and stiff, though. Yes, you have a one-wire knock sensor (it's grounded through the block). The shield on the knock sensor wire is connected to ground ONLY at the ECU; at the knock sensor it just stops. But you're only replacing up to the "pigtail" connector, and that has both ground and signal. You don't really want to be soldering anything, and certainly not trying to "splice" wires. You should remove the connector pins at each end, and recrimp new pins onto your coax. Re-pinning connectors is not for the faint-of-heart, but once you do one the rest are pretty easy. |
Great info, thanks! I'll see if I can scrounge up some of this wire and have a go at it. While I'm in there I will look check for breaks in the TPS wiring. It seems like the PO might have overcooked the engine and fried this harness. It was pretty crispy and stiff when I disconnected it to pull the engine.
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Rusty Mcbuckets, For your code 52 Scope103 is trying to tell you to replace the Pigtail that goes to the Knock Sensor first before your go cutting and splicing wires. It can be ordered from your local toyota dealer and is not very expensive. It is approximately a foot long and has a connector on each end. For my 94 it is part 82219-35010. You will have to remove the upper and lower intake to do this. looks something like this
https://cimg2.ibsrv.net/gimg/www.yot...be2b0963a4.jpg |
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Originally Posted by mholme
(Post 52413540)
Are you sure? He has a ‘91. Harness plugs started to change around this time mid year. Might have the old type harness and wouldn’t want him to order the wrong part. |
The sensor and harness were replaced with new Toyota parts when the engine was rebuilt a few months ago. My problem is probably between that harness and the ECM.
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I went through this. I checked and checked everything, my sensor and harness were only a few thousand miles old after an engine rebuild, just like you. In the end, I changed the entire wire and used a shielded wire and so on. Didn't work. I was too lazy to take top off for new harness and sensor, so I did the next available option, install a new sensor on the engine hoist clip. It has been working perfectly (as far as I can tell anyway, if the engine isn't properly adjusting for minor knocking I don't know for sure) but no code 52! :)
If you search in google 'yotatech code 52 solve' you will find many threads. I think I have a thread for my progress on that as well. |
Well I have a little update. I pulled the TB to check the TPS again since it was giving me bad readings at the closed throttle position. I removed it completely and noticed it made a rattling noise. Turns out it was a cheap POS sensor and had a little glob of solder rolling around inside shorting it out. I installed and adjusted a Toyota sensor and that fixed the code 41 and made the trans shift normally.
The 52 still pops up at random intervals. Last night I drove across down and did a little experiment. I cleared the ECU before I left and recorded the time that the code came on to see if there was a pattern. On the first drive it popped on at 17 minutes. 10 on the second drive, 2 minutes, and about 30 seconds on the last drive. The CEL turns off every time I kill the engine. I took it for one last drive last night so I could check the timing after the code came on, but I drove about 5 miles and it never came on. When I get some more time I will get a voltmeter on it to check for wire breaks and such. Is this code supposed to keep the CEL lit until it's fixed? Or is it normal for it to go away every time I turn off the ignition? It comes on seemingly randomly. I'd think a wiring issue would cause it to pop right away. |
Still battling with this crap. I verified continuity of the knock sensor signal wire. I checked the resistance, and it was at .5 ohm (I am not sure what it is actually supposed to be, I just know 0 is bad). I even got a new sensor and pigtail, hooked them up outside the engine for testing, and it still pops the code almost immediately. Is this starting to point to ECU trouble? I opened it up and didn't see any obvious damage or corrosion, but I have seen other threads stating that their capacitors had bad leakdown. I'm starting to wonder if the electrolytics in this thing are starting to break down from age.
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Did you actually replace the wiring from the connection at the pigtail harness all the way back to the pin at the ECU? What worked for me was extracring the knock sensor wire and harness connector, from end to end, from a 1995 4runner in a junkyard. I had attempted this 2 times with harnesses from older models with no success. I even put a brand new Toyota sensor in the block after chasing the threads to shiny metal. I noticed the ‘95 wire harness was in much better shape than the previous ones I pulled. So I pinned it in to the ECU harness connector and plugged it up to the previously installed new pigtail/sensor. No cuts or splices and grounded right back into the factory crimp. I took the truck for a drive and....Code 52. So at this point, I was pretty frustrated. I went ahead and bought a cheap, like 10 dollar cheap, sensor off of amazon. I ordered a new factory pigtail as well. I drilled and tapped the driver side engine hook, screwed in the amazon sensor, plugged in the pigtail and took it for a drive and...NO CODE 52. I absolutely despise hacks, so I got a weekend and moved the external setup I had, new pigtail and 10 dollar sensor, back to where it belongs and the code did not return. Just for S’s & G’s, I took my previously purchased Toyota sensor and pigtail that had been living in the valley, and screwed that set up into the engine hook, took it for a drive and....Code 52. Swapped the harness back correctly and it’s been fine ever since. So for me, it was two problems- I already knew my wiring was jacked up from a previous owner’s motor swap. The pigtail wasn’t even plugged in when I bought it, and couldn’t be plugged in. The transplanted engine was a ‘93. My truck is an ‘88 with different connector types. The second problem turned out to be a bad Toyota sensor, which I thought was possible, but didn’t want to believe it after $175.00. If my amazon sensor fails, at least now I know I can troubleshoot with a new sensor through the hook if need be, before tearing it apart again. |
Originally Posted by mholme
(Post 52418915)
Did you actually replace the wiring from the connection at the pigtail harness all the way back to the pin at the ECU? What worked for me was extracring the knock sensor wire and harness connector, from end to end, from a 1995 4runner in a junkyard. I had attempted this 2 times with harnesses from older models with no success. I even put a brand new Toyota sensor in the block after chasing the threads to shiny metal. I noticed the ‘95 wire harness was in much better shape than the previous ones I pulled. So I pinned it in to the ECU harness connector and plugged it up to the previously installed new pigtail/sensor. No cuts or splices and grounded right back into the factory crimp. I took the truck for a drive and....Code 52. So at this point, I was pretty frustrated. I went ahead and bought a cheap, like 10 dollar cheap, sensor off of amazon. I ordered a new factory pigtail as well. I drilled and tapped the driver side engine hook, screwed in the amazon sensor, plugged in the pigtail and took it for a drive and...NO CODE 52. I absolutely despise hacks, so I got a weekend and moved the external setup I had, new pigtail and 10 dollar sensor, back to where it belongs and the code did not return. Just for S’s & G’s, I took my previously purchased Toyota sensor and pigtail that had been living in the valley, and screwed that set up into the engine hook, took it for a drive and....Code 52. Swapped the harness back correctly and it’s been fine ever since. So for me, it was two problems- I already knew my wiring was jacked up from a previous owner’s motor swap. The pigtail wasn’t even plugged in when I bought it, and couldn’t be plugged in. The transplanted engine was a ‘93. My truck is an ‘88 with different connector types. The second problem turned out to be a bad Toyota sensor, which I thought was possible, but didn’t want to believe it after $175.00. If my amazon sensor fails, at least now I know I can troubleshoot with a new sensor through the hook if need be, before tearing it apart again. |
Originally Posted by Rusty McBuckets
(Post 52418924)
You actually got me thinking about something... I am an idiot and didn't screw the sensor into anything. It is basically just zip tied a hose right now. The sensor needs to be grounded doesn't it? And nope I haven't rewired it just yet. I wanted to make sure my wiring was in fact bad before I went through that hassle. You had a great idea there, and I think I will try the same method if this factory wire turns out to actually be bad. Thanks for the info!
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Originally Posted by Rusty McBuckets
(Post 52418924)
... and didn't screw the sensor into anything. It is basically just zip tied a hose right now. ...
That and the grounding too. Without a ground, and without a solid acoustic connection, the ECU will not "hear" from the sensor, and you get the code. |
My sensor is still on the engine hook and I havent seen code 52 for about 2 years or so. Granted, it may not be in a position to dot is job 100% effectively. I also installed all new wiring right up to the ECU.
And as scope said this device needs to have a rigid connection to the engine block. If you tap it in the engine hook make sure the hook is fastened tightly to the block |
That’s not surprising to me that it “works” permanently mounted to the hook. As long as the minimal voltage is created by the knock sensor and the wiring is good, I guess the ECU would be happy with that. I just didn’t trust it to detect what it is supposed to detect while sitting there. That’s why I moved it. I doubt it would pick up detonation from there. I ran it on the hook for about two weeks without the code coming back. My gas mileage went from about 14MPG to 17MPG mounted there, and now in its correct location, it’s still the same. Plus, my hard hot restarts went away. Thought it ran ok with the code, but now I know it ran like crap. The knock sensor is only torqued to about 11ft/lbs if I recall, so you don’t need to go crazy tightening it down for *testing on the hook. |
I will fix it if i ever take the top of the engine off for repairs before i do a swap to another engine.
To test if it will pick up any knock I advanced my timing until I got the code. So, I know it works, But it most likely wont pick up the more minor knocks. thinking about it the only code 51 and 52 issues I've read on this form have been related to the knock sensor and the knock sensor wiring. I don't recall reading any code 52 that was a legitimate knock problem of the engine. But if I remember correctly the ecu does use knock sensor information to adjust the timing to some extent.? Do I remember that correctly? |
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