Service Function

Service Function
The procedures must be followed when working on the hydraulic system:
During work on the hydraulic system, the hydraulic pump relay K6318 must be disconnected to prevent unwanted starting of the hydraulic pump. The hydraulic pump relay K6318 is located in the E-box.

Important: The pump must not run dry under any circumstances!

As soon as the door or luggage compartment is opened, the SMG control module activates the relay of the hydraulic pump, even if the ignition (terminal 15) is switched off.
Do not reconnect the hydraulic pump relay K6318 for the entire duration of the repair.
In the service function "Vent hydraulic system", the request to reinsert the hydraulic pump relay K6318 appears.

Sequence for handling the hydraulic system during repairs:
1. Run service function "Preliminary work on the hydraulic system". This removes the pressure from the hydraulic system for a level check.
2. Ignition (terminal 15) off and pull out hydraulic pump relay K6318
3. Replace defective component
4. Top up hydraulic fluid (Pentosin) up to the target filling level. The expansion tank is located beside the transmission. NB: The expansion tank must be without pressure!

Note: Points 5, 6, 7 and 8 are only to be carried out when the hydraulic system was opened beforehand. If the hydraulic system was not opened, continue with point 9.

5. Ignition (terminal 15) on
6. Start service function "Service functions" and in the test module both "Vent actuator block" and "Vent clutch operating cylinder". Only reinsert the hydraulic pump relay K6318 when the test module requests this.
7. Run service function "Preliminary work on the hydraulic system". This removes the pressure from the hydraulic system for a level check.
8. Check the target filling level in the expansion tank once again and add hydraulic fluid if necessary.

This approach is particularly important if there is no or too little hydraulic fluid (Pentosin) in the hydraulic unit.

9. Reinsert the hydraulic pump relay K6318 if point 6 was not performed beforehand.