Knock Sensor Question

[BigGuySpoolin89]

I am a new member and a 1st time supra owner!

I bought my 89 7mgte last week with the knock sensor code. I have rewired them and put new sensors in. The new sensors i got were the square plug sensors. First questions is: Does it make a differance between the round and square plug sensors? (FYI: i did get new plugs for the new sensors also). Second question is: Could this be the ECU? I clear the code, start it up and it runs great as long as i dont try and take off fast and stay in vacuum. I am a noob to supras so try not to flame to bad.

O and i have used the search button!!!

Thanks for any help

 

[Rollus]

Hello,

I won't tell my life but just a short story.
I've just bought a rebuild engine to replace my tired one.
This new engine has round plug sensors. My old one has square plug sensor.
With round I had code 52 (knock sensor also), and an erratic engine run. With square, no problem.
The difference between the 2 engine is that the new was for M/T and the new for A/T, so sensors are different between each transmission...

So in my experience, sensor are different and cannot be exhanged from one type to the other..

Maybe others will have better idea or explanation.

++

 

[hvyman]

No. The sensors are different between pre89 and 89+.

Your fine using the different plug sensors. They both do the same exact thing.

And have you checked codes again?

Did you ground one side of the shielding?

You did use shielded wire right?

 

[BigGuySpoolin89]

yes i used shielded wire... i just used some that i had (coaxle type)
and yes i did ground one side of each wire on the ecu side.

 

[hvyman]

I highly doubt its the ecu. 7m ecu's never go bad.

Either one of the sensors are bad or the ecu doesnt like the wiring you used.

 

[BigGuySpoolin89]

Hmm... I guess a another rewire is in store since they are new sensors... Off to radio shack for some better wire

 

[CyFi6]

Cant comment on the compatibility of the square plug knock sensor for sure, but seeing as most Toyota knock sensors operate the same, I don't see that as being the problem.
Did you do a continuity check on your wiring? Check for short to ground? Make sure you mess with the harness while checking in case there are any intermittent problems. Once that checks out make sure the connector itself and the pin in the connector are good.
Check that the sensor housing is properly grounding to the block.
After that you can test the sensors. First off, make sure they are not internally shorted to ground.
De-pin or back probe the ECU connector and put your multimeter on AC volts and take it out for a drive. I saw anywhere form .2 to .3 AC volts on a good sensor/wiring while on boost. The dead sensor showed .02VAC.
If there is signal getting to the ECU, the ECU is the culprit, though like already stated- unlikely.

 

[BigGuySpoolin89]

Thank You all for the help... Time to do a rewire then some wire chasing... Damn glad i grabed some b*er it might be a long night.

 

[jonahs_supra]

i had to rewire my knock sensors not to long ago
i grounded the shielded wire closest to the sensors on my strut tower

been running great for 3 months now with no codes

 

[hvyman]

Stock there grounded by the ecu along with some other grounds. Usually just easier and cleaner to do that.

But what ever works works.

 

[jetjock]

Stock is grounded to the intake manifold...

 

[hvyman]

Ya but the grounds link together at the ecu. I guess i worded wrong.

 

[BigGuySpoolin89]

Well... rewire went off without a hitch but still didnt fix the code. Im taking it to a shop tomorrow. If i had more time i would diagnose more but i need it done asap. Gas is killing me with the timing being pulled. I will let yall know what the verdict is. I tried multiple grounding points including just grounding on one end and on both ends. Anyway.... I will let yall know what it is.

 

[Rollus]

I'm sure squared and round aren't compatible.

In Epc, there are 2 reference : 1 Toyota and 1 Denso. We cannot exhange.

I've just had the same issue 10 days ago.

Voltage checking is a good way to check wiring.

 

[speedfreak]

maybe you have a slight knock try tapping it with a wrench and see if it throws the code

 

[jetjock]

^ Won't work. Knock isn't what sets the code...

 

[shaeff]

maybe you have a slight knock try tapping it with a wrench and see if it throws the code

No.

^ Won't work. Knock isn't what sets the code...

To expand on what JJ said, read what the error code actually means:

52 Knock Sensor Signal
Diagnosis

Open or short circuit in knock sensor signal.

Trouble Area

Knock sensor circuit
Knock sensor
ECU

If you care to notice, everything Code 52 represents is related to electronics/wiring, not to detonation/rodknock, etc...

 

[speedfreak]

yes already read up on it after being corrected, just threw it out there cause it works for me with my ems, which after learning about it i can hardly believe it works so well with my stand alone

 

[BigGuySpoolin89]

I took the car to an electrical master and the verdict is the knock sensors that i got, which are brand new, are giving the ECU the wrong resistance back which in turn is causing the code. So i ordered some OEM round plug sensors again just need to get the round plug clips again. I get to pick those up this week i guess. He did give me a thumbs up on my wiring job tho. He did also say if that didnt fix my problem then it is my ECU but he said that it is very rare. I also had him check to make sure there wasnt a knock that i wasnt hearing and it came out with the all clear on that. I just need to reshim the valves.

Thanks for the help

 

[shaeff]

I took the car to an electrical master and the verdict is the knock sensors that i got, which are brand new, are giving the ECU the wrong resistance back which in turn is causing the code. So i ordered some OEM round plug sensors again just need to get the round plug clips again. I get to pick those up this week i guess. He did give me a thumbs up on my wiring job tho. He did also say if that didnt fix my problem then it is my ECU but he said that it is very rare. I also had him check to make sure there wasnt a knock that i wasnt hearing and it came out with the all clear on that. I just need to reshim the valves.

Thanks for the help

It wouldn't matter if there was a knock anyway. Knock doesn't cause code 52.