Vehicle speed signal
â–¶ How to fix
Check the circuit for shorts and breaks. Check whether the tachograph has also generated any fault codes.
What you'll see
No driver-visible symptom recorded.
System reaction
No system-reaction text recorded.
Diagnostic depth
Detection
The speed signal from the tachograph has been implausible or there has been no signal at all.
Possible cause
Short circuit or open circuit. There may also be an internal fault in the tachograph.