Checking pneumatic headlamp range adjustment on standard headlamps A. Checking adjustment range - ra820a1404011x(4011)

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

Model 140

Preliminary work:

Front lamps adjusted (Maintenance manual volume 3).

A. Checking adjustment range

Fig 1: Connection Diagram

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Engine	start.
Regulating switch (3)	move from position 0 to position 3.

Fig 2: Screen Display - Low Beam

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Light/dark cutoff of low beam	shifts from "A" to "B".
Knurled disk or measuring screen on headlamp beam adjuster	move until adjustment line is in position "B".
Value on scale	between 33 and 48 cm. If these values are not reached, check vacuum at positioning elements in headlamps (see table), tester for vacuum 201 589 13 21 00. Vacuum levels not reached, check vacuum system for leaks. If these vacuum levels are reached, check ease of movement of reflector and stroke of positioning element.

VACUUM LEVELS AT POSITIONING ELEMENTS IN HEADLAMP OR OUTPUT OF REGULATING SWITCH

Position of regulating switch	Vacuum in mbar
0	400 ± 30
1	290 ± 30
2	200 ± 30
3	50 ± 30

Special tool

Fig 3: Identifying Special Tool (201 589 13 21 00)

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NOTE: The vacuum for the headlamp range adjustment is tapped at the vacuum distribution block (arrow).

The vacuum distribution block (arrow) is located in the passenger footwell behind the foot rest.

Fig 4: Locating Vacuum Distribution Block

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Vacuum distribution block

3 To headlamp range adjustment switch (input, violet)

4 To headlamp positioning element (left, violet yellow)

6 From pneumatic control module (PSE, A37 or A37/1, white)

7 Intake manifold vacuum (gray)

9 From headlamp range adjustment switch (output, violet yellow)

10 To headlamp positioning element (right, violet yellow)

Fig 5: Identifying Vacuum Distribution Block

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Repair note

The repair can be performed best as follows:

To repair use a standard control valve assembly and cut off the supply lines (2) without changing the line cross section. Proceed in exactly the same manner with the control valve (1) in the vehicle. Then install the new control valve in the vehicle with rubber connectors.

Fig 6: Identifying Supply Lines And Control Valve

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Checking ease of movement of reflector and stroke of positioning element

NOTE: Remove headlamp unit on vehicles as of approx. 03.94.

Move reflector (11) all the way up with adjustment screw (12).
Remove housing cover on headlamp unit and remove positioning element (13) from bayonet lock by turning 45??176 to left.
Vehicles up to approx. 02.94

Fig 7: Identifying Reflector, Adjustment Screw, Element And Retaining Clip - Vehicles Up To Approx. 02.94
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Press red retaining clip (14) off of positioning element (13) and pull positioning element (13) off of ball head on pull rod.
Move reflector (11) by hand and check for easy movement.
Remove positioning element (13) and connect to control line.
Allow engine to run and turn range control switch from position 0 to position 3.
Vehicles as of approx. 03.94

Fig 8: Identifying Reflector, Adjustment Screw, Element And Retaining Clip - Vehicles As Of Approx. 03.94
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Measure plunger stroke (a) at positioning element. The stroke should be 3.0 ± 0.2 mm.
If this value is not reached, replace positioning element.
Reassemble in opposite order.
NOTE: When installing the positioning element (13) always reinstall red retaining clip (14).

Fig 9: Measuring Plunger Stroke
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