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 mph 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, presents as aa Major Bummmer to me.....
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 Hertz, 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 Density AOD car that needed idle speed control...
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