300E 4MATIC (124.230) L6-3.0L (103.985) (1990)
Transfer Case Clutch: Technical Service Bulletins
4Matic System - Changes and Information
TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS
Date: October 1991
Ref. No. 28/6
Subject:
MODELS 124.230/290 (4MATIC)
A.
ELECTRICAL SELECTION SWITCH INSTEAD OF SERVICE VALVE
B.
BLEED VALVE FOR CENTRAL DIFFERENTIAL LOCK (ZS) CLUTCH
C.
MULTIPLE-DISC CLUTCH FOR FRONT WHEEL DRIVE (AV) WITHOUT CONTACT PRESSURE
D.
MODIFIED 4MATIC HYDRAULIC UNIT (A7/2)
E.
HYDRAULIC DIAGRAM
F.
ELECTRICAL WIRING DIAGRAM
A. ELECTRICAL SELECTION SWITCH INSTEAD OF SERVICE VALVE
As of May 1991 production, the service valve previously used to turn off the 4MATlC system is replaced with a normal operation/service selection
switch (S7/3). The switch is located on the right inner side of the component compartment wall (Figure 1).
To turn off the system, unplug the connector and reinsert it in position "Test". The 4MATlC warning lamp comes on and indicates that the system has
been turned off.
To turn the system back on, switch off the ignition, unplug the connector and reinsert it in position "FUNKTION". The ignition must be switched off,
otherwise the 4MATIC warning lamp will remain lit.
Before performing any diagnosis or repair of the hydraulic system, release system (accumulator) pressure at the pressure release screw (15, Figure 2).
To do so, open the pressure release screw (16) approx. 1/2 turn. The hydraulic oil will flow to the hydraulic oil reservoir via the return line. When
closing the pressure release screw (16), torque screw to 20 Nm.