Cruise Control Variable Relector Vehicle Speed Sensor Voltage output verses speed

[xctasy]

According to my research, the common VR electronic speed sensor used on some speed density, all criuse control , and all Fox Tbird/Cougar XR7's, VII's and LSC's.

The cruise control runs off a variable Reluctor disk on the standard cable speedo drive



http://vb.foureyedpride.com/showthre...roubleshooting

[QUOTE=JACook;1612943
To check the electrical continuity of the VSS circuit, you should see 200Ω-300Ω between the dark
green/white wire and ground. (This wire should also show a voltage signal when the car is moving,
that is proportional to speed.)
[/QUOTE]

From the F truck forums and Variable Relector info on the net.

"On an AC, permanent magnet sensor, both AC voltage and frequency increase with the speed of the trigger wheel. The AC voltage should range from

0 volts at 0 MPH to 3.5 volts at 30 MPH. Frequency should increase from 0 Hz at 0 MPH to about 125 Hz at 55 MPH"


The EECIV spec XF-AU Aussie Falcns had 102Hz = 37.28 mph (60km/h)


I've just ruined my second Bernstein NPN sensor, and need something that produces not more than 5 volts positive, and a square wave form for my data logger.

I'm thinking of a straight wire hookup to my VR sensor.

[xctasy]

What a very strange, but very cool system.. It's just the 8000 plips per mile, early EECIV compatibale 8 pulse per revolution VRS system, with a variable voltage sqaure wave form from 20 mph onwards. It does have some funny features on sub 20 mph voltage polling, technically able to poll back down to 7 mph in some circumstances.

Certain versions of the EEC III, EEC IV and most EEC V's require an 8000 pulse per mile vehicle speed sensor signal from the PSOM (speedo module), which is just like all other EEC-IV equipped vehicles

Other later EEC V applications use a 16000 or 40000 pulse per mile VSS signal.



I'm told that some of the CFI or Speed Desnity AOD Fox varaints poll down to 7 mph, and allow idle speed conditioning.



Sadly, the periodic zero moh to 19.9 mph null readings won't do what I need it to do, as like some ABS circuits, it has no reliable squarewave below 20 mph to log distance travelled. Its circumstantial, and as such, presnts a Major Bummmer.....

I could probably use a prescaler to create a digital sqaure wave form from an SN95 hub, but I can get another Proximity sensor tommorw in the post for 95 US.


I jacked up my car, and ran the standard Hetz, A/C Voltage and Ohms resistance checks from zero to 62 mph, with my metric speedo registering in KM/H. Note that there is no voltage going up to 32 km/h or 20 mph, but once invoked, the voltage can be recorded right donw to zero, so there is an interesting voltage speed, Hertz resolution

0 km/h, 0 mph 0 Hz, zero volts AC
12 km/h, 7.4 mph, but 0.016 volts AC on over run
See picture

20 km/h, 12.4 mph 0 Hz, zero volts AC
30 km/h, 18.6 mph 0 Hz, zero volts AC, but 0.033 volts AC on overun
See picture

32 km/h, 19.9 mph 0 Hz, 0.00 volts AC
32.2 km/h, 20.0 mph, 0 Hz, 0.019 volts AC
40 km/h, 24.9 mph 0.056 volts AC
50 km/h, 31.1 mph, 0.083 volts AC
60 km/h, 37.3 mph 102 Hz, 0.109 volts AC
70 km/h, 43.5 mph, 0.149 volts AC
80 km/h, 49.7 mph 0.186 volts AC
88 km/h, 54.7 mph 125 Hz, 0.223 volts AC
See picture

100 km/h 62.1 mph, 0.273 volts AC
See picture



The square wave form kicks in after 19.9 mph on the upward rise, with zero Hertz cycles per second on my Cat IV multimetervoltage and the voltage increasing steadily from 20 mph on upwards.


The on the decilne after 20 mph, it records right down to 7 mph, assumably for the one Speed Desnity AOD car that needed idle speed control...

[xctasy]

wELL, I've tried to make the Fox VR sensor work, but its designed for other purposes Ford engineers had in mind in the late 70's, not for a roading technician's list of must haves. I was hoping that the 8 plips per revolution reluctor would allow a square wave form logging down to "stop start" walking speed, as required by Autocross Halda, Brantz and other Route position meter. But it doesn't. There are other speedo pickups that do, the Fox system isn't really difficult, but I wanted a truly digital solution. Ford system is half digital, half anologue, and it hasn't helped me.


I had no choice but to set up another Bernstein proximity sensor, and JB Weld/Devcon expoxy in four extra M10 30 mm long set screws with the hex head filled in with a cut down Allen keyhead Arildited to the set screw.

Mr Bernstein, JB Weld, Mr Allen and Mr Tu Pack Araldite® from Selley's Australia saved my life










It was a lot harder, I thought I could just drill four holes, and run an M10 1.5 MM tap and die through it, but there wasn't enough metal to do it.

The requiremnt I have is to be able to log distances of 9-1/2 inches along the road, and with a four stud wheel and 77 inch rollout (loaded) 190/65 390 tire, I can get down to only 19.3 inches with four studs, or 15.5 inches five stud.

I can't fit 10 studs on the inner wheel pitch center diameter, so I'm stuck with 8 3/4" bolt heads on a 108 mm 4-1/4" PCD, and that's going to have to be used when I go Five stud as well.



I'm scratching my head on how to make a 10 bolt even spaced sesnor ring on the back of a five stud brake disk...that's my next project.

Hope this has helped somone here...

[qikgts]

How about mounting the required amount of bolt heads to a ring and then mounting that ring to the inside of the rotor.

That would allow you to start fresh with bolt head size and spacing.