Speedometer Head, Wiring, or Sender Unit?
Sensor Test. [Peter KL Milne] The sensor is bolted on the rear face of the differential behind the Panhard rod with a tied-on electrical connector. It senses the rotation of a toothed ring attached to the crown wheel inside the differential. The twisted pair wires from the sensor (one Brown (740) or Brown/White (940) and the other Green/White) are shielded right into the boot area. Inside the boot area where the filler pipe comes up to the filler opening, they route through a little sealed plastic box at the rear of the wheel arch thence to the large A-pillar connector at the front of the driver’s door and then to the back of the instrument panel. These in turn route into the panel through a small four pin connector behind the speedometer (740) or the larger passenger side A-connector (940) at the rear of the instrument panel which carries these two wires into the speedo. These connectors may work loose. You can test the sensor and wiring at this panel connector. [Tip] I had a dead spe
