DR_F_OPEN; Clutch F Modulation Solenoid Valve; Open circuit
Switch off ignition; Disconnect electronics incl. transmission cables; Connect transmission checking cables; Measure resistance of the proportional valve (pin 5 against pin 19) Nominal value: 10...15 ohm; Measure resistance of the proportional valve against ground (pin 19 against ground (KL31) / housing) Nominal value: > 10 Mohm; Check cable TCU -> transmission; If you find deviations from nominal value, check wiring and component;
What you'll see
No driver-visible symptom recorded.
System reaction
Activate "Central Solenoid Disconnection Unit";Switch off Comfort start;
Diagnostic depth
The total current of all current regulators is significantly lower than theoretically necessary Readback voltage is 0V Control frequency is lower than minimum permitted control frequency (f_act -> 0Hz); Current regulator indicates fault; AIM switched on or off
Transmission shifts to neutral (gear loss) Retarder is no longer available;