4MATIC - Modified Control Unit/Planetary Gear Set (54/65)
Publication date: 1991-03-01Reference number: 54/65
Supersedes refnos: 28/5
4MATIC - MODIFIED CONTROL UNIT/PLANETARY GEAR SET
TECHNICAL SERVICE BULLETIN
Reference Number(s): 28/5, 54/65, Date of Issue:
March 1991
MODEL 124 4MATIC
A. MODIFIED CONTROL UNIT
B. BLEEDER VALVE FOR FRONT AXLE DRIVE (AV) CLUTCH
C. HELICAL PLANETARY GEAR SET
Model(s): 1990-on Mercedes-Benz 300 E 4MATIC, 300 TE 4MATIC
Group: 28 - 4MATIC Automatic-Engaging Four Wheel Drive; 54 - Electrical System
Bulletin No.: 28/5, 54/65
Date: March 1991
A. MODIFIED CONTROL UNIT
In July 1990, a modified control unit was phased into production.
Note the following:
- This control unit replaces the previous version.
- Once the control unit is reinstalled or the battery reconnected, the unit will automatically adapt itself to the vehicle rear axle ratio. This process occurs when the vehicle is driven for approximately 10 seconds at a speed exceeding 12.5 mph (20 km/h) with the steering wheel in the straight ahead position without applying the brakes. Prior to this process, the 4MATIC system will not engage. As a result, a functional test of the 4MATIC system, or driving the vehicle off a dynamometer using the front wheels, is not possible until the unit has completed the adaptation process.
B. BLEEDER VALVE FOR FRONT AXLE DRIVE (AV) CLUTCH
Since September 1990, the transfer cases are provided with a bleeder valve (EAV) in order to allow improved bleeding of the AV clutch piston chamber and the hydraulic line.
BLEEDING
WARNING:
Observe safety precautions including the wearing of safety glasses!
With engine running, parking brake engaged, and selector lever in "P" position, attach bleeder hose, open the bleeder valve (EAV). See Fig 1 . Close the bleeder valve once the hydraulic oil flows out free of bubbles. Check and correct oil level in reservoir.