Function description: electro pneumatic closing aid - ra72001400260x(0260)

Model 140

Location of components

Fig 1: Identifying Electro Pneumatic Closing Aid Components Location

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Function

Front - rear doors

When the doors are closed to the second catch (drive catch) the supply pump for the closing aid receives a ground signal from a separate microswitch located in each of the door locks.

NOTE: On vehicles with closing aid the following three catches are present:

Initial catch (first catch)
Drive catch (second catch)
Main catch (third catch)

On vehicles without closing aid the drive catch (second catch) is not present.

The supply pump starts running supplying a pressure of 2.5-3 bar to the pneumatic output for each of the doors or trunk lid. The pressure is fed to the pneumatic element, which is connected to the tumbler of the lock by means of a lever mechanism causing the door to close.

If the supply pump detects a pressure of 2.5-3 bar via built-in pressure switches or an undefined signal at the microswitch the pump, or, if a number of control points are actuated, but not simultaneously, the associated output is switched off (valve closed).

The locks are then locked mechanically in the third catch.

The doors can also be closed in the previous manner (without closing aid).

Block diagram

Fig 2: Doors Block Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Trunk lid

When the trunk lid is closed the tumbler switch (which also switches the trunk lamp) disconnects the circuit to ground, the supply pump starts running supplying a pressure of 2.5-3 bar to the pneumatic element integrated into the trunk lid. The trunk lid is closed by the striker eye attached to allow motion (striker eye retracts).

A microswitch (striker eye switch) is located on the moving striker eye to indicate the position of the striker eye to the supply pump.

The closing eye may not function properly when the trunk lid is opened and closed quickly.

Emergency actuation

If the closing aid on the trunk lid does not function due to a defect, an emergency actuation (30) is provided.

To close the trunk lid press the red lever (30) to the left, press in the striker eye (100) and move the lever back to a horizontal position. Close trunk lid.

Fig 3: Identifying Emergency Actuation

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Removal of condensed water

One minute after the ignition is switched on, all pneumatic elements are supplied with a vacuum for 2.5 s. This procedure is repeated twice at intervals of five minutes. Then the process is restarted every ten minutes. Five seconds after the last pressure feed all actuated pneumatic elements are supplied with vacuum once for 2.5 s.

Safety period

If one or more inputs to the closing aid supply pump are switched directly one after another twice by the safety reaction (pressure switching point not reached) regeneration is only possible by interrupting the connection to terminal 30 momentarily (e.g. removing fuse 9) (fuse box for 17 fuses in rear) or disconnecting the plug on the pump).

The safety period is dependent on the voltage and is multiplied by the number of points actuated.

Electric Wiring Diagram:

see "Electric Wiring Diagrams, Model 140, Volume 2",

Diagnostic description, trouble-shooting see "Diagnosis Manual, Body"