Am I doing this right and if so is my Det sensor OK and what do I need to do next to fix. Code 32 with ECU Talk
I can't remember what the reading is supposed to be, but I know when I had code 34 the det sensor still had some resistance but either wasn't enough / too much (so it was determined as faulty). I just bypassed it in the end, pending engine out at some stage.
No Earth with the plug Unpluged the ECU side Male Plug I have no Ground, but the Knock Sensor Side does so now I am even more confused, Help please.
det sensor plug only one wire goes to the det sensor and the other is only a shield wire. There shouldn't be any continuity between those wires going to the det sensor.
Ok Just pulled 2 Knock Sensor off my spare motors one has a broken outer housing where the plug goes in the other looks in good shape, on both of them one of the pins has continuity to the metal base and the centre hole where the bolt goes thru (so therfor when bolted to the motor it goes to ground) When I measure between the two pins the broken one comes up with no Ohms reading at all but the other one reads 560K Ohms. So I still need to know if this is Ok and therefor need to look else where for the fault Code 34 Jnock Sensor 0 starts Via ECU Talk. Please Help.
Measure resistance between Measure resistance between the male plugs (the female plugs go back to the ECU and unless you have a break between the female side of the plug and the ECU - unlikely but I have seen this), the money is on the loom between det sensor and the male plug. Should see ~500 Ohms between the 2 male plugs. Just bypass the whole thing with a 1Meg Ohm resistor between the two female plugs. Then clear the code.
This is how I think it works: There are two wires going through the connector: One is the SIGNAL wire, which comes from terminal 23 on the ECU and goes to the knock sensor. The second is simply a SCREEN around the SIGNAL wire, and is not part of the knock sensor circuit. The ECU looks at the resistance to ground via the SIGNAL wire and through the body of the knock sensor. Normally this is about 1M Ohm. If the resistance is much higher it means the SIGNAL wire has broken somewhere between the ECU and the knock sensor. This raises a code 34. This has nothing to do with the SCREEN. The SCREEN should be grounded (to keep noise out of the SIGNAL wire). It seems it's always grounded on the ECU side of the connector, and sometimes it's also grounded on the knock sensor side (in the knock sensor harness). Putting a bypass resistor across the female connector creates the 1M Ohm path from terminal 23 to ground via the SCREEN ground. For this to work the SCREEN has to be properly grounded on the ECU side. Measuring the resistance between the wires on the knock sensor harness (that is between the lugs on the male connector) is meaningless. It may have continuity, it may not. It's the resistance to ground through the SIGNAL wire and the knock sensor body that matters.
Agreed but checking the resistance between the male terminals gives you an indication whether the det sensor is within specs. Even if it is, the issue can be between the female terminals and the ecu as you said. I've had several scenarios where the det sensor was OK, but a persistent code 34 meaning the wiring between female terminals and ECU was suspect. In one case, instead of disturbing the 20 year old wiring loom, I ran an earth from ECU pin 23 to a ground inside the passenger footwell with a 1Meg Ohm resistor inline. This was the quickest way to resolve the code 34.
Found this comment No there is no easy way to test a knock sensor. They are a piezo-electric sensor, which can only be tested by exciting them with a frequency sweep(and typically high voltage). Each differenty type of sensor has different frequency 'modes', which is steps of frequency at which they will resonate. Even knowing the exact modal frequencies of a piezo electric actuator/sensor, it is still very hard to distinguish mechanical stresses and fractures in the material. Easy answer is, 'no', sorry. If it's bad enough that the ECU is telling you it's bad, then there's no point in diagnosing further. Definately check continuity on all wires from ECU to the engine room harness(for the sensor), before buying a new one.
Whoaa - confusion! I thought you were trying the fix the code 34. That has nothing to do with excitation of the the piezo-electric sensor. A code 34 doesn't mean the piezo-electric sensor is not working. Its quite easy to test for what causes a code 34.
This is my take on it - Have checked several det sensors now, 500 K ohms is normal if you're testing the sensor with DC voltage, as in with a DMM. But since it's an inductor ( wound coil ) it will have a different / higher resistance ( impedance for the purists ) if AC is applied to it. I believe that this is why we need to use a 1 meg ohm resistor to bypass it, rather than a 500 K ohm resistor. Don't take that as gospel though
is this any good to you? http://www.twinturbo.net/nissan/300...tion-Sensor-How-it-Works-amp-How-to-Test.html
Make sure the knock sensor and vct plugs aren't plugged into in other, I had code 34 for ages, turned out I had them plugged into the wrong ones -Mikey
