Speed Sensor AC Voltages

[Ronald]

Hi, Can you help with the speed sensor AC Voltage.

Symptoms, at idle the speedo will flicker 0 to 100 Km/h approx and when driven the speedo reads 185km/h (full scale) and occasionally it will read correctly then go faulty again.

Disconnecting the Speedo Sensor I get the following AC Voltage Results;

339mV (0.3VAC) when removed from the vehicle and spun clockwise as fast as I can manual spin.

NB: the manual says 0.5V AC approx

3.69V AC approx at 50Km/h

4V AC at 60 Km/h

5V AC at 80 Km/h

If this is correct then I will have to investigate the Instrument Panel which visually appears Ok.

Thanking you,

Ronald with the 1991 GQ Nissan Patrol 4.2D