no power to knock sensor?
no power to knock sensor?
so my knock sensor died on my 95 and I picked up another one (used) installed it, reset the ECU and I'm still throwing code 34!! I decided to disconnect the little subharness and use a test light with the ignition on and I get nothing! How can i get power to everything but the knock sensor is that even possible? anyways I don't even want to think about ripping the harness all apart. I tried looking in the FSM and I can't figure out where the damn thing even gets power from. I didn't check for continuity in the signal wire, but I'm guessing not having power is the problem here.is there a way I can jump power from something else like the TPS or something or could that cause bigger problems? you'll have to forgive me I'm stupid when it comes to circuits and stuff.
Re: no power to knock sensor? (blckkat)
How tight did you crank it on?
you mean the Knock sensor itself? as tight as I could given the space constraints. I'm guessing your thinking a bad ground is to cause, but I tested the power coming from the harness clip itself using a low voltage test light that I grounded to the chasis. tested the light on both the MAF and the TPS to make sure the ground was good.
No, if you overtighten the KS, it can cause it to read as if it were bad. If you did not break the crystal, then it will be fixed by backing the bolt out and tightening it to spec.
If you are using a 12v test light, you won't get anything anyway, since it will be a 5v signal. This is because it is a hot source coming from the computer, and they never use a hot source coming from the computer unless it is a reference voltage. They provide ground in that case.
EDIT: the KS makes the voltage, it is not provided any.
Loosen it and tighten it to specs, then see if you have a code.
Modified by Chezedik at 6:56 AM 3/29/2007
If you are using a 12v test light, you won't get anything anyway, since it will be a 5v signal. This is because it is a hot source coming from the computer, and they never use a hot source coming from the computer unless it is a reference voltage. They provide ground in that case.
EDIT: the KS makes the voltage, it is not provided any.
Loosen it and tighten it to specs, then see if you have a code.
Modified by Chezedik at 6:56 AM 3/29/2007
Re: (Chezedik)
Yes the signal is generated chemically by the sensor. The power going to the KS is for heating the sensor.
Actually, it not chemical, there is a crystal inside the knock sensor, that when vibrated creates a voltage. It is called the piezoelectric effect. The only way to test it is to get a multimeter and check resitance on the white wire to ground. It should be about 10 Mohm.
Oh, and get rid of that ****ing test light before you fry your computer, and get a multimeter.
Oh, and get rid of that ****ing test light before you fry your computer, and get a multimeter.
Re: (Chezedik)
Your thinking of knock sensors--look it up--the signal is produced by a chemical reaction.
check it outhttp://auto.howstuffworks.com/question257.htm
check it outhttp://auto.howstuffworks.com/question257.htm
Right, we are talking about a knock sensor. The reaction that takes place in an oxygen sensor could be described as chemical, but the zirconium would act only as a cathode. In effect it is the oxygen differential (from inside to ambient) that causes the voltage to be created. At a perfect stoich you have .45v so with a larger differential (rich) you have closer to 1v, and less differential (lean or not installed) you have closer to 0v.
Re: (Chezedik)
what's the tightening spec for the knock sensor? i couldn't find it in the FSM, there's no way I'll be able to fit a torque wrench in that maze under the manifold. I'd say its tightened to around 15-25 ft-lbs.I'm surprised my test light didn't pick up any power though, its a low voltage one that picks up 5 volt sources. which is why a question if its getting power.....meh I'm just going to try the resistor trick and see if it works. I'm tired of monkeying with this stupid sensor, its not like I need it anyways.
Test lights:1) can fry computer systems2) still cannot deal in voltages less than 1v3) cannot create voltage where there isn't any
On the line going to the sensor voltage doesn't come from the computer. Voltage is created by the knock sensor. I would put loctite on the bolt, and tighten it only until it contacts the block, otherwise you can warp that crystal and the thing doesn't work as designed.
Yes, you do need a knock sensor, particularly if you intend to boost.
On the line going to the sensor voltage doesn't come from the computer. Voltage is created by the knock sensor. I would put loctite on the bolt, and tighten it only until it contacts the block, otherwise you can warp that crystal and the thing doesn't work as designed.
Yes, you do need a knock sensor, particularly if you intend to boost.
Re: (Chezedik)
Ha HA--LOL--Just want to make sure that your up to speed on those KS'sChezedik wrote:Right, we are talking about a knock sensor. The reaction that takes place in an oxygen sensor could be described as chemical, but the zirconium would act only as a cathode. In effect it is the oxygen differential (from inside to ambient) that causes the voltage to be created. At a perfect stoich you have .45v so with a larger differential (rich) you have closer to 1v, and less differential (lean or not installed) you have closer to 0v.
DERRRRRRRRRR