Central Locking System - New Pneumatic Harness
REF. NO. 80/21TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE: May 1994
SUBJECT:
MODEL 202
NEW PNEUMATIC LINE DESIGN
A. CENTRAL LOCKING (CL)
B. ORTHOPEDIC/MULTI-CONTOUR SEAT BACKREST (OSB) FOR DRIVER'S SEAT
C. ORTHOPEDIC/MULTI-CONTOUR SEAT BACKREST (OSB) FOR DRIVER'S AND FRONT PASSENGER SEATS
D. MANIFOLD VACUUM ASSIST (MVA)
As of December 1993, pneumatic harnesses utilizing a push-on type design have been phased into production. All pneumatic connectors, sockets as well as distributors are equipped with barbed fittings which ensure proper sealing.
The 7-connection pneumatic distributor (10-connection in vehicles equipped with OSB) on the PSE control module has been eliminated.
A. CENTRAL LOCKING (CL)
Pneumatic line assembly for central locking
A pneumatic line (1, Figure 1) connects the PSE control module (A37/4 or A37/5) with a six connection pneumatic distributor (3), in order to pressurize or depressurize the CL actuators (4-9). The CL actuators (4-9) are individually connected to the six connection pneumatic distributor (3) by separate pneumatic lines. For identification purposes there are letters printed on the six connection pneumatic distributor to indicate which actuator is connected to the pneumatic line.
Testing for leaks in CL in vehicles as of December 1993
The pneumatic line assembly and actuators for CL can be tested for leaks by pulling off the pneumatic line (1, Figure 1) at the PSE control module (A37/4-A37/5). If a leak is found, the pneumatic line which runs to the nonfunctional CL actuator must be disconnected at the pneumatic
distributor (3).
After eliminating the leak (traced to the pneumatic line or CL actuator), the pneumatic line must be reconnected to the pneumatic distributor (3, Figure 1) using a hose connector. For proper test procedures of CL actuators, refer to Diagnostic Manual, Body and Accessories, Volume 1.
B. ORTHOPEDIC/MULTI-CONTOUR SEAT BACKREST (OSB) FOR DRIVER'S SEAT
Pneumatic line assembly, for OSB driver's seat
A pneumatic line (1, Figure 2) connects the PSE control module (A37/5) with a two connection pneumatic distributor (3) in order to pressurize the OSB. From the two connection pneumatic distributor (3), one pneumatic line (A) connects to the OSB reservoir (4). The second pneumatic line (B) connects to the OSB pneumatic hose set (under the driver's seat). For identification purposes, letters are printed on the two connection pneumatic distributor to indicate vacuum line routing.
C. ORTHOPEDIC/MULTI-CONTOUR SEAT BACKREST (OSB) FOR DRIVER'S AND FRONT PASSENGER SEATS
Pneumatic line assembly, OSB for driver's and front passenger seats
A pneumatic line (1, Figure 3) connects the PSE control module (A37/4 or A37/5) with a six connection pneumatic distributor (3) in order to pressurize the OSB. From the six connection pneumatic distributor (3), one pneumatic line (A) connects to the OSB reservoir (4). Two additional pneumatic lines (B,C) connect to each of the OSB pneumatic hose sets (under the driver's and front passenger seats). The three remaining outputs of the six connection pneumatic distributor (3) are plugged off. For identification purposes, letters are printed on the six connection pneumatic distributor to indicate vacuum line routing.
Testing for leaks in the orthopedic/multi-contour seat backrest (OSB) in vehicles as of December 1993 production
The pneumatic line assembly for OSB can be tested for leaks by pulling off the pneumatic line (1, Figure 3) at the PSE control module (A37/5) and plugging off the ends of pneumatic lines A-C. If a leak is discovered, the pneumatic lines A-C must be disconnected one at a time from the pneumatic distributor (3). After eliminating the leak (traced to a pneumatic line or the OSB reservoir), reconnect the pneumatic lines using hose connectors. For proper test procedures of the OSB control valves and seat inserts, refer to Diagnostic Manual, Body and Accessories, Volume 1
D. MANIFOLD VACUUM ASSIST (MVA)
Testing for leaks in the manifold vacuum assist (MVA) in vehicles as of December 1993 production
Pneumatic line assembly, for MVA
The pneumatic line assembly for MVA can be tested for leaks by pulling off the pneumatic line (1, Figure 4) at the PSE control module (A37/4 or A37/5), then pull off and plug the pneumatic line at the vacuum distributor block (28). If a vacuum leak is discovered, repair or replace the defective pneumatic line.
Parts needed for testing
Repair note:
In the event a leaking pneumatic line is repaired or replaced it must be reconnected to the pneumatic distributor with a 40 mm long hose connector.
Parts Information
Complete pneumatic line assemblies are available from the PDC's.
Please note that minor repairs may not necessitate the replacement of an entire pneumatic line assembly. Pneumatic lines may be assembled from individual components as listed in the Parts Microfiche. Lines should also be assembled after stock of the complete assemblies is depleted.
Parts Information