REVELTRONICS UTCOMP-3 User & Assembly Manual page 53

Q: Where to find the signal from the VSS speed sensor?
A: If you have an electronically controlled counter (e.g., on "cable") the easiest and fastest way is to check whether such a signal is connected to the
radio socket (some radios have the option volume up with increasing speed) – the ISO pin no.1, designated generally as VSS, Vehicle Speed, GALA,
GAL, etc. Another place where this signal is for sure (in case of an electronically controlled counter) is a tachometer (instrument cluster) – output is
usually marked on the diagram as VSS, Vehicle Speed, Speed1, Speed2 etc. If you have a mechanical counter, "with the cable" the signal is to be found
in the ECU socket (marked as Vehicle Speed Sensor - VSS) or take a signal directly from the speed sensor which is mounted in the gearbox of the
vehicle (sensor has three terminals: power, ground, and the pulse signal).
Q: My car has no speed sensor what can be done?
A: Even some cars with a mechanical counter "on the cable" have the speed sensor located in the gearbox (its signal is fed to the ECU). However, if the
car actually have not a VSS sensor, you can always assembly additional hall sensor with magnets.
Q: I have car with diesel engine , does fuel consumption function will work?
A: If there is a signal in the car that represents the injection time (voltage, pulse, where pulse width is the time of injection), assuming a constant fuel
supply pressure, so it will work. Injection times (or pulse width) should decrease with increasing engine speed (idling). Such a signal is found in most
diesel engines with unit injectors or common rail. You should look at the ECU or the fuel injection pump controller for such a signal. Diesels with
mechanical injection pump "on the cable," certainly do not have such a signal. Latest common-rail engines also does not have such signal, but in most
cases you can measure fuel consumption from injector control signal (signal converter may be required) and from fuel pressure sensor.
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