96-up Knock Sensor - Who has one sitting around?

[robertisaar]

i need someone to test the circuit resistance of the OBD2 knock sensors, i've READ that they're 100K ohm units, i need to confirm this though.

[Superdave]

I probably do.. i will look tomorrow after work.

[robertisaar]

much appreciated, Dave...

looking into using the OBD2 knock sensors with the later OBD1 PCMs, if they are 100K, we would need to run a ~4050ohm resistor in parallel to ground to drop them down to the 3.9K the OBD1 PCMs are expecting.

through this method, it would likely be possible to string multiple knock sensors into a single circuit, should an engine be equipped that way.

[Superdave]

It would be nice to run the dual 3500 KS's for sure... my old 3.1 KS picks up knock just fine though..

[robertisaar]

i looked it up on rockauto, apparently, all of the 60V6 and northstars use the same knock sensor up until 1995, then the 96 and later units are used on all 3100 and 3400 units.

the 2-wire setup used on the non-VVT 3500s seems to be used on pretty much every other motor GM offered from 04-current.

[beastberetta]

i think i have either one or 2 3500 non vvt knock sensors sitting in my garage i didnt use them...you can have them if you want them.

[robertisaar]

i don't want them, i just need to know their electrical characteristics.

[Superdave]

100K ohm on the dot.

I looked all around for it, then realized that's the one i have hooked up to my ECM test bench.

[robertisaar]

did you have a 100K working natively with the OBD1 ECM?

[Superdave]

well, when i smack it with a hammer it shows knock counts... that was just the intended purpose for it.

[robertisaar]

the 100K of resistance in place of 3.9K should have set the knock sensor DTC due to being WAY under range and made it otherwise not function....

hmm...... my understanding of the knock circuit not correct?

[Superdave]

it was hooked up during one of the dataloggs that i sent of your $A1 testing, i don't remember it setting a code.

[robertisaar]

crazy that it works, the ECM should be reading an incredibly low voltage AC signal and either constantly generating knock counts or tripping the code...

i may need to look into this.

[3400-95-Modified]

May also be right on the fine line of over sensitive, hence why a hammer hit causes it to register knock.