Solenoid valve 4 and 5 are low resistance, 5 to 6 ohms and so the voltage drop across them will be low. To check if the solenoids resitance is correct 1 to 3 should read around 30-35 ohms, 4 and 5 5 to 6 ohms and the speed sender is 1k. The manual says "if clicking noises of the transmission relay in the control unit cannot be heard replace the control unit.
There are many other tests which use the VAG 1527 which could identify it further.
