No Ignition but speed pulses present
1) Investigate if the vehicle has been under environmental disturbances like vibrations etc. 2) Check motion sensor operation and the cable harness. 3) Replace sensor if found faulty. 4) Check for evidence of tampering of the motion sensor, cable harness or the tachograph. 5) Check if speed pulses are being injected through front connector.
What you'll see
tbd
System reaction
No system-reaction text recorded.
Diagnostic depth
Ignition is off but tachograph recieves speed pulse from sensor on B3 (connector B, pin 3).
This is a known problem and can occur when the edge of a cog lies in front of the motion sensor, and the vehicle is parked but slightly moving. This phenomenon” can happened due to strong wind and transport by a ferry etc. Other possibilities are: * Fault in cable harness. * Fault in motion sensor. * The vehicle have been towed.