Rusty67:
I have a tough time with electrical stuff (missing gene or something tragic) but the VSS is alternating current so you should be able to measure AC volts (or current) on a multimeter. If it is fancy enough, it may even give RMS (root mean squared) - akin to 'average' - voltage.
I've never measured the VSS but I do know that it is an alternating current/voltage/frequency signal.
That's it, lol.
HTH,
Chris
I have a tough time with electrical stuff (missing gene or something tragic) but the VSS is alternating current so you should be able to measure AC volts (or current) on a multimeter. If it is fancy enough, it may even give RMS (root mean squared) - akin to 'average' - voltage.
I've never measured the VSS but I do know that it is an alternating current/voltage/frequency signal.
That's it, lol.
HTH,
Chris
Not easy.
Yes. Unfortunately building the converter is a job for an electrical engineer. I don't know of any converters which are marketed as "VSS to voltage". If you want to learn to make one yourself, Google "frequency to voltage converter".
Yes. Unfortunately building the converter is a job for an electrical engineer. I don't know of any converters which are marketed as "VSS to voltage". If you want to learn to make one yourself, Google "frequency to voltage converter".
It might help if we knew what you are trying to accomplish.
I could be wrong, but I do not think that the VSS sensor's output is voltage based. I think it is frequency based.
In any case, if you have a high end multi-meter, try the "Hz" setting. If the sensor is frequency based, the Hz will vary with the shaft speed.
I could be wrong, but I do not think that the VSS sensor's output is voltage based. I think it is frequency based.
In any case, if you have a high end multi-meter, try the "Hz" setting. If the sensor is frequency based, the Hz will vary with the shaft speed.
Sooooo. Have you tried measuring the VSS output with a DVM? Pay attention to the frequency (not the volts).
There is a write up in the Ford Service manual regarding the priciples of operation and how to trouble shoot the VSS sensor. Seems like a great place to start for information. PM if interested.
There is a write up in the Ford Service manual regarding the priciples of operation and how to trouble shoot the VSS sensor. Seems like a great place to start for information. PM if interested.
For a variable-reluctance speed sensor I'd probably suggest considering something in the MAX9924 series of integrated circuits to parallel-tap the VSS wires to obtain a clean, logic-level frequency output. You then have a couple of options:
First you could use a purely analog approach using, say, a frequency-to-voltage converter and a comparator to trip a relay when the frequency (and thus vehicle speed) moves above a certain threshold.
Second, you could consider a small microcontroller to measure frequency directly and control the relay. As a digital designer I tend to favor the microcontroller approach because it allows you to easily do things like hysteresis (e.g. enable the reverse lock out at 6 MPH but don't re-enable is until, say, 3MPH is shown...) and is generally less finicky than purely analog approaches.
Needless to say, unless there's already a box out there (hint) you're going to be looking into a bit of engineering...
First you could use a purely analog approach using, say, a frequency-to-voltage converter and a comparator to trip a relay when the frequency (and thus vehicle speed) moves above a certain threshold.
Second, you could consider a small microcontroller to measure frequency directly and control the relay. As a digital designer I tend to favor the microcontroller approach because it allows you to easily do things like hysteresis (e.g. enable the reverse lock out at 6 MPH but don't re-enable is until, say, 3MPH is shown...) and is generally less finicky than purely analog approaches.
Needless to say, unless there's already a box out there (hint) you're going to be looking into a bit of engineering...
The MAX9924 (or something like it) will provide a convenient high-impedance front end to your circuit that won't interfere with the operation of the PCM in reading the VSS. Because a VSS is a magnetic device its output will (a) be AC, (b) increase in amplitude with increasing speed and (c) increase in frequency with speed. It'd be nice to have a single piece of silicon do that side of the interface, giving you a nice logic level pulse train to work with.
Interesting reading for a 94-98 VSS:
http://accutach.com/Documents/VSSCharacterization.pdf
Depending on the style of sensor you're interfacing to (gear-driven like earlier units or magnetic pickup as later units were) you might want to do a bit of probing to calibrate your system.
Interesting reading for a 94-98 VSS:
http://accutach.com/Documents/VSSCharacterization.pdf
Depending on the style of sensor you're interfacing to (gear-driven like earlier units or magnetic pickup as later units were) you might want to do a bit of probing to calibrate your system.