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Discussion Starter #1
Hi everyone, hope you are all safe and well.

I am hoping somebody here will be able to assist me in diagnosing my problem Knock sensor P0325 code on my 2000 2zz.

I have searched high and low on several forums for similar related posts but have not come across and answer for my issue.

As you can imagine my symptoms are CEL on dash, ignition retardation for obvious reasons, and occasional misfire depending on engine load (caused by ignition timing i imagine). Obviously under these conditions i am unable to rev over 7k and Lift is non existent... which i so desperately miss!!

Anyway, I have tested the OEM sensor (single pole) fitted as per repair manual and have no continuity through sensor. I have also confirmed that it preduces a small AC voltage when bench tested so assume the sensor is not at fault. After inspecting the wiring loom and jumper cable I detected the wire insulation was damaged exposing the inner core that had signs of water ingress. I have since repaired the wire and tested resistance through harness to pin 27 at E5 connector at ECU - very minimal resistance through wire and of course continuity is present.

With my findings now indicating an ECU issue (pray that its not), I am curious to know if I should see a 5 volt signal to sensor from ECU in order for the knock signal to be calculated? Would anyone know if this is the case? Also, would anyone know where the sensor harness gets its shielding earth from?

Any info would be extremely appreciated.

Thanks in advance Guys.
 

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We only fixed ours with buying a new harness from the stealer ship, about 12 bucks..

Can’t answer your questions though. We had multiple part options to throw at ours.
 

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Discussion Starter #3
We only fixed ours with buying a new harness from the stealer ship, about 12 bucks..

Can’t answer your questions though. We had multiple part options to throw at ours.
Sheik Ya Bootie, Thank you for your reply.

When you say a new harness, is that the jumper loom between the sensor and harness connector you refer to, or the entire harness itself? I assume from the cost it is the jumper loom?

Cheers
 

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Discussion Starter #5
Ok thanks, I'm sure I have a spare one tucked away from a previous engine change.

I'll try that in the week, see how it goes.

Thanks again
 

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Discussion Starter #6
Ok... So I managed to find my spare jumper cable and fitted this morning but still no fix.

I also swapped my newish NGK spark plugs with the originals that caused no issues previously, knowing they were gapped correctly also... Again no fix.

Fitted a spare crank position sensor aswell that I had spare and as expected, no fix.

I have found another 2zz knock sensor which I am yet to swap out but convinced it's caused by another issue.

Would anybody be so kind to check if I should see a reference voltage from pin 27 at ECU or at knock sensor connector with ignition on and or engine running? This would put my mind at ease greatly :)

Thanks Guys
 

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I'm going way back & am not sure.... It might be sensor-specific '00-'01 or '03+.... Either +5VDC or +12VDC.
 

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Discussion Starter #8
Thank for your reply 2way 👍🏻

Ok, I was lead to believe that I should have some form of reference voltage there, but either way I have nothing... Guess I'll have to source an ECU 😔
 

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Discussion Starter #9
So I contacted a Toyota master tech today and explained my dilemma. He took a look at the wiring diagram and stated that the diagram shows no sign of giving a reference feed, but instead looks to be grounded. This would clarify what I see on the attached wiring diagram.

Being that I have swapped out 3 sensors in all (2 of which being genuine denso units and the other after market) I very much doubt they are at fault.

Would somebody be willing to see what AC voltage they get from the sensor on engine idle and in a higher rev range when engine hot please? At least then I will have something to compare to and may see a difference.

Cheers Screenshot_20210406-191710.png
 

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As I said, it's been a while & I haven't recently verified. But from my old posts, the single wire knock sensor has +5VDC and the AC signal runs +/-5VAC max. The service manual shows +/-1.5VAC typical. The later two-wire sensor has a "supervisory" 12V circuit to an "end of line" resistor in the sensor. With an additional CEL code that shows a wiring issue either open or short in the knock sensor circuit. Not sure about the AC portion of that sensor. But, it's been a long time since then and, unfortunately, the diagram I based much of that info on has since been deleted by the poster.

In any event, you can prove out the harness to the sensor with an ohmmeter. You can test for a shorted knock sensor. You can test the knock sensor with an AC voltmeter & striking the engine near the sensor. If all those tests are ok, then you're looking at the ECU being bad.
 

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Discussion Starter #11
Thank you very much 2way, that info is priceless to me at present.

As stated previously, I have tested the wire between ECU for shorts to live and ground, open circuit and resistive circuit including jumper loom.

All 3 sensors are not shorted and have been bench tested at which all 3 give an AC voltage dependant on strike force to vice (approx. 0.5acv) but I have not tested with sensor fitted with engine running whilst tapping close by... What I do have is 0.04acv with engine at idle, surely this is incorrect? I might add that this was the case for both denso units. These figures are the reason I'm reluctant to commit to ECU repair or replacement to be honest.

Either way I'm having the ECU in the next few days to dismantle and visually inspect, so maybe something obvious will crop up.

Thanks again 2way
 

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FYI, the manual says for that code:
"No knock sensor 1 signal to ECM with engine speed, 2,000rpm or more"
 

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I don’t know on uk cars but fwiw... USA cars can swap in and out ecu plug and play.. Oz cars need the key and umm.. reader thing.. to match the ecu. Pretty sure I thought it needed the bcm but believe that was incorrect.

Also the 2003 on ecu is different.
 

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I don’t know on uk cars but fwiw... USA cars can swap in and out ecu plug and play.. Oz cars need the key and umm.. reader thing.. to match the ecu. Pretty sure I thought it needed the bcm but believe that was incorrect.

Also the 2003 on ecu is different.
Pretty sure our UK models require programming in but unsure if anything else follows ie, key reader, instrument cluster and bcm.

Yes I am aware that the 03± ECU is different, however, I only know they are due to the rev limit reduction, I am not aware of any other differences.

Pretty sure I'll have a tough time sourcing an 00-02 ECU being that many purchase them to swap into their 03 on cars, but maybe I'll get lucky.

Thanks for your reply
 

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Hi everyone, hope you are all safe and well.

I am hoping somebody here will be able to assist me in diagnosing my problem Knock sensor P0325 code on my 2000 2zz.

I have searched high and low on several forums for similar related posts but have not come across and answer for my issue.

As you can imagine my symptoms are CEL on dash, ignition retardation for obvious reasons, and occasional misfire depending on engine load (caused by ignition timing i imagine). Obviously under these conditions i am unable to rev over 7k and Lift is non existent... which i so desperately miss!!

Anyway, I have tested the OEM sensor (single pole) fitted as per repair manual and have no continuity through sensor. I have also confirmed that it preduces a small AC voltage when bench tested so assume the sensor is not at fault. After inspecting the wiring loom and jumper cable I detected the wire insulation was damaged exposing the inner core that had signs of water ingress. I have since repaired the wire and tested resistance through harness to pin 27 at E5 connector at ECU - very minimal resistance through wire and of course continuity is present.

With my findings now indicating an ECU issue (pray that its not), I am curious to know if I should see a 5 volt signal to sensor from ECU in order for the knock signal to be calculated? Would anyone know if this is the case? Also, would anyone know where the sensor harness gets its shielding earth from?

Any info would be extremely appreciated.

Thanks in advance Guys.
Hi,

I can tell this code is related to a possible fault within the knock sensor and its wiring all they way back to the ECM, but just to make sure and discard some stuff, is this related to a 1ZZ to 2ZZ swap? Have you been always using at or above 91 octane in your fuel? I did a swap to 2ZZ and I was used to using 87 octane on my 1ZZ engine. Since I knew no better I kept adding the same low grade fuel by mistake and knocking was happening. 2ZZs needs 91 or above to properly work and yes, you probably know this, I'm just hoping your not struggling with the same thing I did. Also, I know there is some sort of difference between the knock sensor in a 03 GT engine vs that of an 00-01, so, that's why I wanted to check whether this is related to a swap or not.
 

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Discussion Starter #20
Hi everyone,

Just to make you all aware that I fixed the knock sensor issue yesterday morning and have covered 180 miles since repair 😁. It goes without saying that I am now a very happy man, full power is back on tap!!

It turned out to be an intermittent short between the knock sensor signal wire and the earth shield around that wire itself (hence why I had previous issues faulting the wiring harness). It was only ever so slightly shorting due to light damage of the wire insulation, and was located approximately 8 inches down the harness from ECU end.

With a bit of luck this info may help someone else one day.

Thank you for all of your inputs, it is much appreciated.

Jase
 
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