Proportional valve, retarder (Y1)
â–¶ How to fix
Check the signal to pin 6 in the connector for the gearbox control unit. Check the retarder proportional valve. Check connectors and connections according to the circuit diagram for the ZF automatic gearbox, refer to group 16.
What you'll see
No driver-visible symptom recorded.
System reaction
No system-reaction text recorded.
Diagnostic depth
Detection
Incorrect signal from the retarder proportional valve.
Possible cause
The gearbox control unit, pin 6, has detected a short circuit to earth in the lead to the proportional valve for the retarder.The voltage has been under 19 V.