Anybody know?
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Anybody know?
Anybody know what the correct voltage is supposed to be for a VSS sensor output on a 94 F-150 with the 5.8L? I have my o-scope hooked up and I am only getting about .5V out of it. It gets a nice clean sine-wave but won't get above .5V. This is a new sensor from napa and it is obviously not working but I don't know what the range should be. Oh and I am getting a code 452 which is VSS error which in turn is causing my E4OD tranny to go into limp mode and shift extremely hard. So any help would be appreciated.
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Yes I rang out the wiring to the PCM but I don't think the voltage is enough and it doesn't vary at all. If I remember correctly this is a variable reluctor? sensor so it should give more voltage as it goes faster correct?
Freshman User
Joined: Mar 2009
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From: Lima, Ohio/Tionesta, Pa
It should be varying voltage. The faster the wheels spin, the higher the voltage, it is a magnetic pulse generator. Make sure you have the oscilloscope on AC voltage, as that is what the VSS will put out.
Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
Here's a good article: Distributor Pickups
It's talking about distributor pickups but they work the same as a VSS.
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Well from what I understand it is supposed to vary the voltage the faster it spins but what I need to know is what the range is. And I stated in the OP that it is getting a nice clean sine-wave it just is not varying the voltage the frequency is but not the voltage.
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Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
As I said, I don't think the VSS varies the voltage. Did you read the link? See the voltage graphs?
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Here is a little tidbit from the link:
The result is an alternating current (AC) voltage that reverses polarity and crosses zero as it the pin aligns with the sensor. The output voltage of this sensor varies with the speed of the engine. This voltage is then chopped/filtered/amplified and used to drive a high voltage/high current transistor that switches the coil current. This signal is used by MegaSquirt-II for ignition timing as well as injector timing in engines with sequential fuel injection.
So yes it does look like it varies the voltage I am trying to check the VSS on the rear axle. But good link lots of good info in there.
The result is an alternating current (AC) voltage that reverses polarity and crosses zero as it the pin aligns with the sensor. The output voltage of this sensor varies with the speed of the engine. This voltage is then chopped/filtered/amplified and used to drive a high voltage/high current transistor that switches the coil current. This signal is used by MegaSquirt-II for ignition timing as well as injector timing in engines with sequential fuel injection.
So yes it does look like it varies the voltage I am trying to check the VSS on the rear axle. But good link lots of good info in there.
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From: spokane wahington
Have you determined that the "pick up" ring that this sensor is reading is in good condition? If not the sensor is likely not to fault. As the link suggested these sensors are rugged and not prone to failure. More commonly are the teeth on the ring, next to your ring gear itself, get messed up and give inaccurate info.
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Joined: Feb 2007
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From: Chicagoland
The frequency is what you want to see increase/decrease. The voltage is irrelevant. You'll need an oscilloscope if you really want to test it. If you know music I suppose you could wire an earbud to it to hear the signal and guess at the frequency. That's about the best I think of short of some pricey test equipment.
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I checked the ring all looked good and I did have an o-scope on it and it was varying the frequency but I think it needs more than .5V to the PCM to read it. That is what I need is what is the minimum voltage it takes and what range should I see.
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From: Chicagoland
.5V is pretty good for what is basically a small, primitive generator. The PCM is quite capable of reading inputs even smaller than .5V so I wouldn't count it out just based on that.