Sym GTS 250 Service Manual page 221

e). Check the signal voltage value for sea-level air pressure:
‧Electric meter negative pole─ Connect to the third pin (Green / Red)
‧Electric meter positive pole─ Connect the middle pin (Black / Red)
☆Note that the detection pin must penetrate the skin of the electric wires to get the correct readings.
4). Malfunction determination:
a). Working voltage =
b). Signal voltage value for sea-level air pressure
c). The higher altitude will reduce the voltage output.
☆ Sea-level air pressure = 1Atm = 101.3kpa = 760mmHg = 1013mbar
5). Abnormal phenomenon and treatment:
a). Sensor malfunction or bad coupler contact.
b). Check Wire harness.
c). PM sensor abnormal, replace with a new one and measure the voltage again.
d). ECU abnormal, replace with a new one and measure the voltage again.
Fig.3 PM Sensor working Voltage measurement
5.0 ± 0.1V
(Like the following figure 4)
=2.87 V ± 0.03 V
Fig.4 PM Sensor voltage signal output at sea level
6
(Under 101.3kpa)