[kamesama980]

If the VSS in the transmission has 2 wires, it's a VR sensor, not a hall effect sensor. it produces a double sawtooth waveform with it's amplitute proportional to speed and proximity to the tone generating magnetics (in this case, the bolts) which is why the MPGuino doesn't see it at low speeds.

If you have a cable driven speedometer it's totally different and I'm in the process of figuring it out because that's how my truck is and my MPGuino doesn't like it.

Sme of the early ABS equipped cars as they get older, the wheel speed sensors start to lose sensetivity and cut out at low speed causing the ABS to kick on coming to a stop on dry pavement. Yours isn't a poor signal from age, it's just below the threshold of the MPGuino