Another Knock Sensor Thread

Joined
Mar 4, 2015
Messages
149
Good morning everyone.
I have had a knock sensor issue now for a few weeks that I cant seem to get rid. I searched and read almost every thread that has the key words "knock sensor" and "code 52" tied to it and none of said threads seem to have a solution.

To make a long story short I was getting code 52 so I replaced the knock sensor with a what was a known good replacement, cleared the codes, restarted the vehicle and code was gone. Thinking everything was cool I went out for a drive to see the difference and as soon as it got up to a normal operating temp the light comes back on. So I test for the code. 52 again. Just for s***s and giggles I swapped out the rear with the one I replaced from the front and still it throws code 52. I now know that it is indeed the front sensor. I pull the front plug again to inspect it. There are no signs of corrosion or any visible defects and everything seems to be intact with the plug. Do I need to test this for continuity as well as the sensor itself? Are there any other little tricks I could try?
 

westafari

Sand Cruiser
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Roanoke, VA
You might need to peel back the wiring harness to make sure the wires running to the sensor are good. Someone had "repaired" the wiring harness on mine in the past and it wasn't immediately visible until I really got in there and looked at it. I ended up getting a Tacoma pigtail from @beno and splicing it into my wiring harness and that cleared up my code. Good luck! Driving around in limp mode is...limp.
 

Dirty Koala

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since you mention code 52, I assume you have either a 93 or 94? 95-97 have a different code for knock sensor (325 and 330) if I recall. In any case, I would look closely at the wiring harness, in particular where it wraps around behind the EGR at the back of the head. That EGR gets real hot and the wiring is way too close to it.
 
Joined
Mar 4, 2015
Messages
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You might need to peel back the wiring harness to make sure the wires running to the sensor are good. Someone had "repaired" the wiring harness on mine in the past and it wasn't immediately visible until I really got in there and looked at it. I ended up getting a Tacoma pigtail from @beno and splicing it into my wiring harness and that cleared up my code. Good luck! Driving around in limp mode is...limp.
That is probably going to be my next step. I see they sell a harness plug. Is the factory wiring all one piece or can this sensor plug end be unplugged and a new one swapped in?
 
Joined
Mar 4, 2015
Messages
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since you mention code 52, I assume you have either a 93 or 94? 95-97 have a different code for knock sensor (325 and 330) if I recall. In any case, I would look closely at the wiring harness, in particular where it wraps around behind the EGR at the back of the head. That EGR gets real hot and the wiring is way too close to it.
Yes I should made that a little more clear. It is a 94. Is the harness all one piece or can I buy a replacement plug end and swap it in?
 
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it is all one harness, but you can do as westafari did and splice the new pigtail in...its just a connector and some heat shrink.
Thanks much for the reply! Ill have to track at back as far as I can see and reach.
 

Dirty Koala

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you could also buy a whole new engine harness from beno...there are a few left in the country. I did that recently...but for another reason.
 
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Mar 4, 2015
Messages
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you could also buy a whole new engine harness from beno...there are a few left in the country. I did that recently...but for another reason.
Beno? Im sorry I am new to the LC world. How much is the harness?
 
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@beno, also goes by the name of Onur. If you need OEM toyota parts, he is your man. Good discount to mud members and a wealth of knowledge about land cruisers that you won't get from the part desk rep at almost all dealers.

Onur: 505.944.5081// onurazeri1@gmail.com
Thank you very much for taking time out of your day to help me out. It is much appreciated.
 
Joined
Mar 4, 2015
Messages
149
I think the whole engine wiring harness is $$$$ but the Tacoma pigtail is $35 or $40 as I recall.
What year Tacoma is this part off of? Is this the correct one Genuine Toyota Wire Loom Knock Sensor Wire Connector Plug 82219-35010?

Yes the whole harness is not inexpensive, approx to $500 after discount, but as this part is now discontinued, they wont last very long. If you need one, better grab one ASAP.
$500?! That is expensive to me! Thats a little bit of gas for my next journey!
 
Joined
Mar 26, 2015
Messages
128
Hey,

I went exactly thru the things you're going thru now....I bought my 1996 SC LX450 with CEL light on....(P0325 and P0330) I said to myself...."CEL light....phhhh!!!....piece of cake...!!!!". Wellll it tuned out to be not that straight forward.....
I changed both of the knock sensors with OEM Toyota.....didn't help.....
After this $180 spent not so wisely I said: "let's take it methodically....I checked the wire harness using a multimeter for continuity and shorts to ground.....everything checked out perfect......, I checked the knock sensors signal shape using a oscilloscope at the ECU pins....looked perfect, exactly as the FSM mentions....
At this point, following the FSM I said "it must be the ECU...." I found a good ECU on ebay and bought it for $80.....so I was excited to try when i got the package....
I replaced the ECU and the CEL stayed off for.....30 min or so...!!!!!!
Welll.....I was sooooo frustrated.....and I took some time to read more details about these engines....and I got hold of some "race quality" fuel (120 or so octane......!!!!!) and the moment I put that fuel in the CEL went OFF.......!!!!!!!
So, with this new piece of info it turns out that actually the engine was in fact knocking and the ECU and knock sensors behave as it should....So, what was causing the engine to knock?....welll... my attention turned out on the EGR system.....So, I checked the modulator, the EGR valve......nothing wrong.....
So, at this point I had a chance to talk to a knowledgeable guy at a local shop specialized in Landcruisers....and the guy casually said: "that damn EGR VSV is acting up, that is the thing that fails usually...."
So, immediately I went and checked the EGR VSV and found it to work ...just partially....I changed the EGR VSV with a similar one I had around from a Celica ST165 engine, cleared the CEL and run the LX....NO MORE CEL.....since
So...for what is worth.....check the EGR VSV.....

regards,
 
Joined
Mar 4, 2015
Messages
149
Hey,

I went exactly thru the things you're going thru now....I bought my 1996 SC LX450 with CEL light on....(P0325 and P0330) I said to myself...."CEL light....phhhh!!!....piece of cake...!!!!". Wellll it tuned out to be not that straight forward.....
I changed both of the knock sensors with OEM Toyota.....didn't help.....
After this $180 spent not so wisely I said: "let's take it methodically....I checked the wire harness using a multimeter for continuity and shorts to ground.....everything checked out perfect......, I checked the knock sensors signal shape using a oscilloscope at the ECU pins....looked perfect, exactly as the FSM mentions....
At this point, following the FSM I said "it must be the ECU...." I found a good ECU on ebay and bought it for $80.....so I was excited to try when i got the package....
I replaced the ECU and the CEL stayed off for.....30 min or so...!!!!!!
Welll.....I was sooooo frustrated.....and I took some time to read more details about these engines....and I got hold of some "race quality" fuel (120 or so octane......!!!!!) and the moment I put that fuel in the CEL went OFF.......!!!!!!!
So, with this new piece of info it turns out that actually the engine was in fact knocking and the ECU and knock sensors behave as it should....So, what was causing the engine to knock?....welll... my attention turned out on the EGR system.....So, I checked the modulator, the EGR valve......nothing wrong.....
So, at this point I had a chance to talk to a knowledgeable guy at a local shop specialized in Landcruisers....and the guy casually said: "that damn EGR VSV is acting up, that is the thing that fails usually...."
So, immediately I went and checked the EGR VSV and found it to work ...just partially....I changed the EGR VSV with a similar one I had around from a Celica ST165 engine, cleared the CEL and run the LX....NO MORE CEL.....since
So...for what is worth.....check the EGR VSV.....

regards,
Thanks for the reply. It is pretty frustrating isnt it? But now that you mention it the first time I pulled codes I got an EGR code as well but that has since gone away, or become dormant. What is good procedure to run said test?
 

slow95z

Always parting 80s
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Dublin GA
 
 
hmm... i also have a knock sensor code, O2 code and EGR code. i wonder if my EGR could be causing all of those. since the truck in question is only used as a hunting truck i just never worried with it but i might need to check it out now. thanks for the tip on the VSV.
 
Joined
Mar 4, 2015
Messages
149
hmm... i also have a knock sensor code, O2 code and EGR code. i wonder if my EGR could be causing all of those. since the truck in question is only used as a hunting truck i just never worried with it but i might need to check it out now. thanks for the tip on the VSV.
I didnt think EGR would have anything to do with it because they are two different systems but since it was explained a little better it does make sense.
 

westafari

Sand Cruiser
Joined
Aug 25, 2014
Messages
212
Location
Roanoke, VA
What year Tacoma is this part off of? Is this the correct one Genuine Toyota Wire Loom Knock Sensor Wire Connector Plug 82219-35010?
Thats different than the one I got but the sensor end looks the same so I'd expect it would work. Info above re: the VSV sounds like something worth running down as well.
 
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