code 52 under load.

2

2ndgenmafia

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so i have the annoying code 52. knock sensor.. cel only comes on after the runner is under load. i can crank it up and itll idle all day with no light... but after i switch gears from 1st to 2nd usually the light comes on. 3.0 with almost 309xxx miles.
 
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2ndgenmafia said:
so i have the annoying code 52. knock sensor.. cel only comes on after the runner is under load. i can crank it up and itll idle all day with no light... but after i switch gears from 1st to 2nd usually the light comes on. 3.0 with almost 309xxx miles.
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Hmm that issue sounds familiar. Maybe try the searching it in the search bar. I seem to recall seeing another post about this a few months back. Might find your answer there. Hope this helps!
 
If you google that code, you'll see how common it is. I'm dealing with the same issue and I'm pretty sure it's the harness wiring. When I pulled heads, I noticed the harness was brittle and hacked, but I only replaced the pigtail at the sensor. I need to go in and rewire the cable all the way back to the ECU with shielded cable.

Also, that code is not load dependent, it's RPM dependent. The ECU is looking for a signal in a specified RPM range and if it does not receive it, it sets a code. Rev your truck over 1600 RPM in neutral and the light will turn on, that's what mine is doing. Check your wiring.
 
Then perhaps it is knocking? Easy and pretty cheap test, on your next fill up, run higher octane fuel and see if that light goes away.

If it does, either the fuel you've been using is really low octane (hi ethanol fuel during winter can do this), or maybe your timing is just a bit too advanced.
 
My truck did the same thing. I would rev and rev in park with co CEL but as soon as I started driving it would pop. I educated myself like crazy trying to fix the problem. Relocated KS with new harness and knock off KS, Changed ECU ran direct wire from KS to ECU triple double checked timing, ohm'd this ohm'd that etc etc. Finally gave up and changed the KS the RIGHT way. OEM Toyota KS, OEM Toyota KS harness and tackled the job yesterday. 11.5hrs later Code 52 as been gone for the last 20miles. Before Code would show up before I even left my driveway.
 
From everything that I've researched and that has been posted, that code has nothing to do with the ECU detecting pinging. It's telling you that it has not received a signal when it expected to, with likely culprits being the wiring, the knock sensor itself or even the components in the ECU or distributor.

I don't know, I'm hardly an expert on these trucks but I'd verify wiring before anything else. My truck has 287k miles on it and every piece of wiring under the hood was falling apart to the touch.
 
Maybe this will help somebody diagnose the issue... So it started after I replaced the leaky valve cover gaskets, I also replaced the vafm. I also replaced new plugs and wires.
 
mholme said:
From everything that I've researched and that has been posted, that code has nothing to do with the ECU detecting pinging. It's telling you that it has not received a signal when it expected to, with likely culprits being the wiring, the knock sensor itself or even the components in the ECU or distributor.
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Exactly what the FSM says. In my '92 version, for the V6 on page FI-112, it doesn't give you a page number to look at for followup (most other codes do), and just lists "Open or short in knock sensor circuit, Knock sensor (looseness, etc.), ECU"

Does it perform any different after this happens? Aside from selling it or maybe issues with passing smog with a CEL, and always having a CEL on so you don't know when you get a code from some other thing, is there any reason to fix it?
 
Yeah, ignore my last post, not sure what the hell I was thinking. The light wouldn't come on if the engine was detonating, it would only come on if the sensor or circuit had an issue.

Some days I just don't think things through.... :confused:
 
giro said:
Exactly what the FSM says. In my '92 version, for the V6 on page FI-112, it doesn't give you a page number to look at for followup (most other codes do), and just lists "Open or short in knock sensor circuit, Knock sensor (looseness, etc.), ECU"

Does it perform any different after this happens? Aside from selling it or maybe issues with passing smog with a CEL, and always having a CEL on so you don't know when you get a code from some other thing, is there any reason to fix it?
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Yes it performs different... It goes into safe mode, and retards the timing...that's why I wanna get it fixed.
 
2ndgenmafia said:
Yes it performs different... It goes into safe mode, and retards the timing...that's why I wanna get it fixed.
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See my above post, save yourself the trouble and change the KS and KS pigtail. 9 out of 10 code 52 problems stems from the harness but believe me, you DON'T want to do this job twice. Spend the extra cash and buy a new Toyota KS as well. If this doesn't fix it, then move on to ECU, Chassis Harness wiring etc etc. At least you will be able to rule out the KS and KS pigtail
 
Had the same issue except my knock sensor and pigtale was functioning just fine. Lean and rich codes were being pulled but would not appear thru jumping the diag. Had a burned #5 with no knock. Issue turned out to be interference from the pigtale connector to the ecu. That was only found out after I replace the 3vze with a rebuilt completed block. First putz around with the new motor code 52! Wtf. Had the harness rewired (electrical and I don't mix lol) and still code 52.... looked like the pigtale got pitched in the new block. Pulled my old knock sensor and had it welded to the engine hook on the block. Old knock sensor tested great and code 52 was gone!

Check the cable running to the ecu. If that is getting a signal at the pigtale connector from the ecu - its the knock pigtale - it gets very crispy in the center of your 3vze so.

Drove the beast for 5 months with the timing retarded becuase of the code 52 hahahah really found out which drivers had road rage on the 405:behindsofa:
 
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I have this issue on mine
mechanic just replaced KS and PT along with a bunch of other work.
I recently bought it and it had a CEL and the 52 code which is why I brought it over to him.

Went to pick it up and idling and revving it up wouldn't always trip the CEL.
Before, in park it would trip at 1800 RPM
Now I could get to 3k.

Cleared the code by removing EFI fuse (read that does it, not sure)

Drove it and CEL tripped at 1800

I looked at the old PT and it was definitely bad..

My mechanic called me a little while ago and told me that he was talking with someone about it and a bad catalytic converter can cause the code due to it being very loud and rattling. Well, my cat was bored out by the previous owner and I was planning on replacing it as it is loud as hell and obnoxious.

He said he has seen this issue numerous times with a bad cat causing a KS issue. Will report back.
 
That's why I'm skeptical to hop into it... I think it may be something else Bc it ran great before I replaced the leaky valve cover gaskets... After that was done is when the cel came on.
 
To do the VCGs you have to remove the plenum. There is about 500 vaccum hoses that you have to take off. Check and re-check that you put them back correctly/ none are cracked. Also the Knock Sensor pigtail attaches to the Enigine harness right under the throttle body. Inspect that and see if any wires are frayed/ pins pulled back from the connecter etc etc. You may have disturbed the KS pigtail enough to case damage.
 
2ndgenmafia said:
That's why I'm skeptical to hop into it... I think it may be something else Bc it ran great before I replaced the leaky valve cover gaskets... After that was done is when the cel came on.
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Like I said before. Just change the KS and pigtail. Start with what is almost always the problem then go from there. I JUST went through this EXACT problem and wasted a lot of time and money trying to fix it different ways because I didn't want to take my engine apart. As soon as I changed the KS and pigtail it fixed code 52. Been great for 200+ miles.
 
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