Propeller shaft speed sensor open circuit.
• Check wiring and connectors - between propeller shaft speed sensor and COO (vehicle without TCO) - between B6 on TCO and COO (vehicle with TCO) - power supply to tachograph ECU unit (vehicle with TCO) • Check propeller shaft speed sensor (vehicle without TCO) • Check tachograph ECU unit for DTCs (vehicle with TCO) • Measure the sensor voltage between signal and ground (vehicle without TCO)
What you'll see
In vehicle without TCO: • No vehicle speed is displayed in instrument cluster • Vehicle distance is not incremented • Shifting to range low gear is inhibited (*) • Cruise Control is inhibited • Generally, all functions dependent on vehicle speed information, is degraded In vehicle with TCO: • No obvious reaction, as long as the tachograph is fully operational (redundant info from TCO is used) (*) During the first 10 seconds after ignition on, it is always possible to shift to range low gear.
System reaction
Amber COO Warning Lamp
Diagnostic depth
Impermissible signal from the propeller shaft speed sensor. The sensor voltage level is within an illegal range. The propeller shaft speed sensor has an open circuit.
• Defect wiring (open circuit) • Defect connectors • Defect propeller shaft speed sensor • Defect tachograph ECU unit (vehicle with TCO)