Knock Sensor test?

[Exille]

Is there away to test it to see if its bad? i would rather not have to replace it as its $180...and im broke

[ILikeMy240sx]

you can measure the resistance according to the FSM specs.

You can find that at http://www.zeroyon.com

[Exille]

i looked in the FSM....it just says continuity should exist....does that mean that there should be some resistance? i dont really understand that bit....i measured the resistance with my $5 radioshack DMM, set it to its highest amount which is 2M ohms, and it came out to be .564..someone help me out? does that mean i have 564,000ohm of resistance? is that good enough to not have to replace my knock sensor?
Modified by Exille at 3:33 PM 3/3/2006

[charlie2020]

More than likely if your reason for replacing it is becasue you keep getting a code for knock sensor the problem is probably in yoru wiring harness and not the actual knock sesnor itself, the shielded wires tends to short to ground, i've fixed 4 S13's and the short to grounds where all in the same place plus or +/- a few inches...

[Exille]

Where is the place?

[Nanaimo]

Indeed, where is the place!?

[sleepyRPS13]

small hammer & timing light. just "tap" w/ hammer area around knock sensor not on sensor. while someone watches the timing retard with the timing gun. it should retard...

if it doesnt check voltage on the knock sensor since generates its own small voltage when senses a vibration. and voltage drop to the wire / ecm.

also get a better dvom, not from radioshack.

note; also knock senors can be easily affected by radio or electromagnetic interference.

[xsblacksx]

i think i got a knock code

[240sHorTy]

Test the knock sensor wire on the ECU harness. You should be seeing some voltage there if the sensor is at 564 KiloOhms. It is supposed to be between 2 and 3 volts when the engine is idling. If it is showing no voltage, you've got a wiring problem. If you are showing out of range voltage, that could be the sensor. I assume you already checked your grounds?

I don't know definitively, but I bypassed my knock sensor with a POT, and the correct voltage was acheived with a resistance somewhere in the 500 to 750 K ohm range IIRC.

The FSM is unclear of the 'correct' resistance, but the voltage at the ECU is given.