knock sensor

Fire & skill

Vintage member
right this is a pain but I'm asking anyways, I have read numerous posts about knock sensors and wiring. I have two wires going to my knock sensor, now I know one of which goes to pin number 27 on the ecu, now what is the other one for??????

people always respond by saying there is only one wire - but I'm telling you there is two connections on my knock sensor and two wires going into it from the plug, what is the other wire? is it an earth? people always respond by saying it is earthed through the chassis when fitted to the block, this is fair enough but still doesn't answer what the other wire is or where it goes -


anyone? :x
 

splmum

Active Member
right this is a pain but I'm asking anyways, I have read numerous posts about knock sensors and wiring. I have two wires going to my knock sensor, now I know one of which goes to pin number 27 on the ecu, now what is the other one for??????

people always respond by saying there is only one wire - but I'm telling you there is two connections on my knock sensor and two wires going into it from the plug, what is the other wire? is it an earth? people always respond by saying it is earthed through the chassis when fitted to the block, this is fair enough but still doesn't answer what the other wire is or where it goes -


anyone? :x
see here

http://www.gtiroz.net/workshop/service-manual/circuit_diagram.pdf

Go page 5, you will find Detonation sensor about the middle bottom of the page
 

Braveheart

New Member
doesn't really show where the other wire goes though :(

I'm thinking of running it to pin 29 on the ecu
No it does not show you....:roll:
From the troubleshooting page it shows to test pin A on sensor ground so I assume that's the signal pin.
http://www.gtirworkshopmanual.com/default.aspx?v=1096
It does not tell you what the value of impedance should be though... only that meter setting range.... :doh:
Maybe pin B on sensor goes to sensor body / engine earth.

Are you going to take the second wire from sensor (B) to ECU ground point then?
 

Fire & skill

Vintage member
No it does not show you....:roll:
From the troubleshooting page it shows to test pin A on sensor ground so I assume that's the signal pin.
http://www.gtirworkshopmanual.com/default.aspx?v=1096
It does not tell you what the value of impedance should be though... only that meter setting range.... :doh:
Maybe pin B on sensor goes to sensor body / engine earth.

Are you going to take the second wire from sensor (B) to ECU ground point then?

tried it, still not working. I'm going to order another one from Bob tomorrow, I have rewired the sensor all the way back to ecu.

I do an ecu check and it shows 34, so I short the pins out again for a few secs then the engine check light comes back on, switch ign off again, do another ecu check - now 55, again I short the pins out again for a few secs then engine check lamp comes on. I then start the engine, switch off and recheck - showing 34 again. I have checked the voltage from ecu and its 5vdc, the original knock sensor fitted to the car is open circuit (testing from lh pin to knock sensor body) I have nother knock sensor which was in the boot of the car, not a good sign I know, but i metered it out and seemed ok, on test its 5vdc from ecu, start car and its 4.8vdc to ecu. I have temp fitted the knock sensor to the chassis and ran one of the plug cables to 29 and the other to 27, so im thinking I have two duff knock sensors
 

Fire & skill

Vintage member
I should also point out that the 'other' knock sensor I have although it looks similiar is different from the original one so may not be up to the job.

does anyone have an idea of the signal voltage I should expect from the knock sensor to the ecu when the car is at idle?
 

Fire & skill

Vintage member
right!

It's all making sense (I hope) the original sensor is definately fuct, the one I found in the boot which seems ok, well I found a part number on it as 22060-7B000 - this is a Nissan part number but not compatible with our car :D

so I have now ordered the correct one 8)
 

Braveheart

New Member
right!

It's all making sense (I hope) the original sensor is definately fuct, the one I found in the boot which seems ok, well I found a part number on it as 22060-7B000 - this is a Nissan part number but not compatible with our car :D

so I have now ordered the correct one 8)
Hope it sorts it out... How much for OE sensor?
And maybe take some impednce and voltage mesurements as it info that is lacking on here!
 

Fire & skill

Vintage member
Hope it sorts it out... How much for OE sensor?
And maybe take some impednce and voltage mesurements as it info that is lacking on here!
I bought the sensor from the bay, cost £35 and its new - listed as for a 300zx.

it arrived today and I've fitted it - now all clear 55 :-D
wired as above, LH pin to 27 and RH pin to 29 on the ecu
 
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pulsarboby

Guest
we recently fitted one of these that a customer supplied and the thing didnt work so ended up fitting a s/h unit i had.

when you look at the listing it does not specify turbo charged cars so whether that has something to do with it or not i just dont know!
when we did an ohms check on the unit it was out of spec and only reading 558mega ohms, now if a s/h unit from gtir reads that then we throw them in the bin as they wont work.
but having said all that it could possibly have been a faulty part which they sent!!!
 

frit

Member
Oh ok, cheers Bob, what is an acceptable reading then? On the workshop manual link on the previous page it just says you need a ohmeter that measures 10Mohm or more, it doesnt tell you what an acceptable value is?
 
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pulsarboby

Guest
well ive discovered that any readings below 565 m ohms they are knackered, a good new one will give a reading of about 580.
ive just done this myself through trial and error, as you rightly say there does'nt seem to be a correct specific reading for them.
 
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