Grammer MSG95EAC Operating instructions

November 2012
Material no. 1 277 338
Repair manual GRAMMER seat suspension MSG95EAC
Page 1 of 1
TABLE OF CONTENTS
Preface
1 Description
1.1 Safety instructions
1.2 Rating plate
2 Diagnosis
2.1 Overview of components
2.2 Overview of faults – Pointing out possible faults that might occur
2.3 Troubleshooting – Locating the fault
3 Repair work
3.1 Seat suspension – removal and installation
3.2 Top cover – removal and installation
3.3 Bellows – removal and installation
3.4 Vertical shock absorber – removal and installation
3.5 Locking mechanism for fore/aft isolator – removal and installation
3.6 Longitudinal horizontal shock absorber – removal and installation
3.7 Fore/aft isolator unit – removal and installation
3.8 Compressor – removal and installation
3.9 Sensor module – removal and installation
3.10 Air spring – removal and installation
3.11 Control / air reservoir – removal and installation
3.12 Cable harness for vehicle connection – removal and installation
3.13 Active module – removal and installation
3.14 Air distributor – removal and installation
3.15 Cable harness for energy bundle – removal and installation
3.16 Cable harness for seat suspension – removal and installation

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
Preface
Page 1 of 2
Notes on these instructions
This repair manual includes information and instructions on how to perform repair
work on the seat suspension MSG97EL of GRAMMER seats.
The repair of the upper seat part is described in the respective repair manual for the
upper seat part to which a reference is made, if required (see repair manual for
upper seat part).
Example:
Remove the cable of the seat occupancy detection system at the upper seat part
(see repair manual for upper seat part).
The seat suspension MSG95EAC forms the basis for illustrations in this repair
manual. In the case of technical deviations in work procedures (due to different seat
suspension designs), refer to the current text or individual chapters of the manual.
Each chapter starts with a list of all preparatory work to be completed before starting
repair. These preparations are described in separate chapters and shall be carried
out without the preparatory steps described there.
For spare part orders, please use the numbers stated in the latest issue of the
relevant spare parts catalogue.
The description of the work procedures refers to the removed seat suspension and
the dismounted upper part of the seat.
Depending on the individual installation situation, some work may also be performed
on the installed seat suspension and/or with upper seat part. For this reason, check
the environment of the installed seat suspension for this possibility before starting
work. The safety instructions of the specific vehicle manufacturer and those stated
in Chapter 1 of this repair manual must be strictly observed.
This repair manual also includes some information on delivery options, if these
require further explanation. Since the scope of delivery depends on the specific
customer order, the actual seat suspension design may deviate from the
descriptions and illustrations in this manual.
The illustrated repair steps refer to the seat suspension for left-hand drive. Different
work steps are to be performed laterally reversed when repairing vehicle models
with right-hand drive.
If not stated otherwise, the directional indications "front, back" and "right, left" refer
to the installed seat suspension regarded in the driving direction of the vehicle.
The document layout is suitable for later use of this repair manual via CD-ROM /
INTERNET / INTRANET.
Basic information on the seat suspension
The seat suspension is provided with a long-lasting lubrication (approx. 10 years).
The lubricating points must be re-greased only after repair work, using an acid-free
multi-purpose lubricant.
In the description of the present repair manual, not all fastening parts might be
mentioned. After repair, it might be necessary to check fastening parts regarding
their factory-made laying, support and securing and to correct them respectively, if
required.

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
Preface
Page 2 of 2
Bowden pull wires, cables and air hoses may only be fastened with cable ties at the
defined spots by hand (loose). Make sure that Bowden pull wires, cables and air
hoses cannot be squeezed or distorted when the seat suspension is adjusted and
the seat moved.
Replace all removed old parts with enclosed new ones. If there is no new part
included, the old one is to be cleaned and checked for its suitability for re-use.
Defective parts and worn parts must be replaced by new ones.
Grammer AG rejects any warranty claims if damaged or worn parts and assemblies
are not replaced by spare parts released by Grammer AG.
Qualified personnel
These instructions offer basic information on proper technical seat repair. The
contents of the work procedures described are intended for professionally educated
technicians with profound product knowledge. This level of knowledge is an
imperative requirement when performing the work and procedures described in this
document.
In order to avoid bodily injury, reduced operational safety of the seat suspension or
damage to it resulting from improperly performed work, all information and
instructions, in particular the safety instructions stated in Chapter 1, must be read
carefully and strictly observed.
As an inevitable matter of fact, GRAMMER AG cannot evaluate all situations and
consequences that may bear a risk of injury for the persons involved in the
described work procedures. For this reason it is absolutely necessary that every
person who carries out repair work at the seat suspension uses his/her professional
knowledge to make sure that his/her own safety will not be put at risk and that the
selected type of repair will not cause any negative effects, in particular with regard
to technical safety.
For this reason, GRAMMER AG disclaims liability for any possible damage of this
kind.
We point out explicitly that all work steps and procedures described are to be
performed with consideration to the applicable directives and regulations stipulated
by the relevant local authorities and in compliance with the provisions on health
protection, prevention of accidents and environmental protection.
Change notification and copyright
The seat suspensions are subject to continuous development. Please understand
that we must reserve the right to make changes in shape, equipment and technical
design. For this reason, the contents of this repair manual cannot be used to
substantiate any possible claims.
Reprint, translation and copies of this manual or parts thereof are admissible only
after written approval.
GRAMMER AG ⋅Postfach 14 54
D-92204 Amberg
Phone [phone] / 66-6822
www.grammer.com
Delivery and factory address:
GRAMMER AG
Köferinger Str. 9-13
D-92245 Kümmersbruck

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
1 Description
Page 1 of 1
TABLE OF CONTENTS
1.1 Safety instructions
1.2 Rating plate
Note:
Please refer to the applicable seat operating instructions for further details.

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
1.1 Safety instructions
Page 1 of 1
1 All inspection, test and repair work must be performed exclusively by adequately
trained personnel.
2 We point out explicitly that all work steps and procedures described are to be
performed with consideration to the applicable directives and regulations
stipulated by the relevant local authorities and in compliance with the provisions
on health protection, prevention of accidents and environmental protection.
3 Special notes in this repair manual are highlighted as follows:
WARNING ...
indicates possible risks for persons and their prevention.
ATTENTION ...
indicates possible damage or deterioration of material and their prevention.
Note: …
introduces an additional explanation for better understanding the work to be
carried out.
Installation note: ...
introduces an additional explanation for better understanding the installation
work to be carried out.
4 Before starting repair work, the following work has to be carried out:
•Disconnect the seat suspension from the power supply.
•Move the seat suspension to the end stops of the lower position.
5 When using oil, grease and other chemical substances, the relevant safety
regulations for the handling and use of these products must be observed.

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
1.2 Rating plate
Page 1 of 1
The rating plate is located on the upper
suspension part at the rear left.
The rating plate shows the following
information (example):
(A) Country of manufacture = MADE IN
XXXXXXX
(B) DESIGNATION = MSG95EAC/741
12V
(C) INVENTORY NO. = 1240014
(D) Year / CW / Assembly
12 19 141:
•Year of manufacture = 12 (2012)
•Built in week = 19 (May)
•Assembly = 141
(E) ORDER NO. = XX 98786400005
•Country indicator = XX
Note:
When orders are placed, the correct
INVENTORY NO. (C) on the rating plate is
always to be quoted.

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2 Diagnosis
Page 1 of 1
TABLE OF CONTENTS
2.1 Overview of components (pages 1-7)
●Pneumatic modules and connecting diagram (page 1)
●Sensor module with pin assignment (page 2)
●Control / air reservoir with pin assignment (page 3)
●Active module and cable harness of energy bundle with pin assignment
(page 4)
●Compressor, compressor cable and pin assignment (page 5)
●Cable harness of seat suspension, electrical connections with pin
assignment (pages 6-7)
2.2 Overview of faults –Pointing out possible faults that might occur
(pages 1-4)
2.3 Troubleshooting – Locating the fault (pages 1-15)
Preconditions for fault diagnosis for each test (page 1)
1 Inspection of the air spring and air distributor (page 1)
2 Inspection of the sensor module (page 2-6)
3 Inspection of the compressor and of the compressor cable (page 7)
4 Inspection of the active module (pages 8-10)
5 Inspection of the cable harness for seat suspension (page 11-13)
6 Inspection of the control / air reservoir (page 14)
7 Deactivation of the emergency programme / reset to normal operation
(page 15)

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.1 Overview of components
Page 1 of 7
Pneumatic modules and
connecting diagram
(1) Active module
(2) Control / air reservoir
(3) Quick-release fastener
(4) Air hose (black):
Hose from air distributor (15) to
control (2)
(5) Air hose (blue):
Hose from air distributor (15) to
sensor module (6)
(6) Sensor module
(7) Energy bundle
(8) Air hose (thin)
Hose from air distributor (15) to 2/2
directional valve in the active
module (1)
(9) Air hose (thick):
Hose from air distributor (15) to 3/2
directional valve in the active
module (1)
(10) Air spring
(11) Catch spring
(12) Quick coupling
(13) Air intake hose / air exhaust hose
(14) Air intake hose / air exhaust hose
(15) Air distributor
16 Quick-release fastener screw
WARNING Damage!
Observe the instructions stated in
Chapter 3.9 and in Chapters 3.14 to
3.16 when pulling off the air hoses
(4, 5, 8) from the quick-release
fastener screw!
(17) Air hose
(18) Nozzle
(19) Compressor
WARNING Damage!
Please observe the notes stated in
Chapter 3.8 when pulling off the air
hose (17) at the connection of the
compressor (19).
(20) Retaining ring of quick coupling
2852
16
15
16
16
2
3
7
1
8
5
20 5
6
19
13
18
9
8
17
12 11
10
9
8
14 12
16
4

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.1 Overview of components
Page 2 of 7
Sensor module with pin
assignment
(1) Sensor module
(2) Retractor (sensor module)
(3) Webbing
(4) Plug of sensor module (3- pin)
(5) Plug of sensor module (4- pin)
(6) Socket (cable harness for seat
suspension)
(3-pin)
(7) Socket (cable harness for seat
suspension)
(4-pin)
(8) Air hose (black):
hose connecting magnet valve block
to retractor
(9) Air hose (blue):
Hose from the sensor module to the
air distributor
(10) Cable harness for seat suspension
(11) Socket of cable harness for seat
suspension (18-pin)
(12) Retaining ring of quick coupling
WARNING Damage!
Observe the instructions stated in
Chapter 3.9 before pulling out the air
hose (9) at the retaining ring of the
quick coupling (12)!
Electrical plug and socket connections:
(A) Electrical connection (3-pin)
between sensor module (1) and
cable harness for seat suspension
(10)
(B) Electrical connection (4-pin)
between electromagnet for 2/2 and
3/2 directional valve at the sensor
module (1) and cable harness for
seat suspension (10).
(C) Electrical connection (18-pin)
between the control / air reservoir
and the cable harness for seat
suspension (10)
2853
P3
P2
P1
P2
P3
P4
P1
45
K4
K7 K8
K10K11K14
11
1
3
6
11
8
7
10
1
9
12
9
A
C
B
4
5
2

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.1 Overview of components
Page 3 of 7
Control / air reservoir with pin
assignment
(1) Control / air reservoir
(2) Plug of control (18-pin)
(3) Socket of cable harness for seat
suspension (18-pin)
(4) Cable harness for seat suspension
Electrical plug and socket connection:
(C) Electrical connection (18-pin)
between control / air reservoir (1)
and cable harness for seat
suspension (4)
2854
C
1
2
34
P10... ...P18
2
P1 P2 P4 P5 P6 P7 P8 P9
3
K9 K8 K7 K6 K5 K4 K2
... K10
K1
K18 ...

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.1 Overview of components
Page 4 of 7
Active module and cable harness
for the energy bundle with pin
assignment
(1) Active module
(2) Plug of active module (3-pin/large)
(3) Plug of active module (3-pin/small)
(4) Seal (large)
(5) Seal (small)
(6) Socket (cable harness for energy
bundle, 2-pin/small)
(7) Socket (cable harness for energy
bundle, 2-pin/large)
(8) Energy bundle
(9) Air hose (thick)
(10) Air hose (thin)
(11) Cable harness for energy bundle
12) Socket of cable harness for energy
bundle (4-pin)
(13) Socket of cable harness for seat
suspension (4-pin)
(14) Cable harness for seat suspension
(15) Circlip
16 Quick-release fastener screw
(17) Socket of cable harness for seat
suspension (18-pin)
Electrical plug and socket connection:
(C) Electrical connection (18-pin)
between the control / air reservoir
and the cable harness for seat
suspension (14)
(D) Electrical connection (3-pin/large)
between electromagnet for 3/2
directional valve at the active
module (1) and cable harness for
energy bundle (11)
(E) Electrical connection (3-pin/small)
between electromagnet for 2/2
directional valve at the active
module (1) and cable harness for
energy bundle (11)
(F) Electrical connection (4-pin)
between cable harness for energy
bundle (11) and cable harness for
seat suspension (14)
2855
7
3
2
8
9
7
4
E
D
F
C
6
5
1
3
2
9
11
13
14
10
10
12
12
P1
K5K6
K10
P2
P2
P1
5
6
10
9
15
11
16
8
4
K1
K2
K3
K4
17
17

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.1 Overview of components
Page 5 of 7
Compressor, compressor cable
with pin assignment
(1) Compressor
(2) Right-angle plug (blue cable)
(3) Right-angle plug (black cable)
(4) Cable harness for seat suspension
(5) Socket of cable harness for seat
suspension (18-pin)
(6) Control / air reservoir
Electrical plug and socket connections:
(C) Electrical connection (18-pin)
between cable harness for seat
suspension (4) and control / air
reservoir (6)
(G) Electrical connection between
compressor (1) and right-angle plug
of black cable (3)
(H) Electrical connection between
compressor (1) and right-angle plug
of blue cable (2)
Cable colours:
sw = black
bl = blue
2856
bl
K10
K2
K10
5
6
5
2
sw
3
4
4
1
H
C
G

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.1 Overview of components
Page 6 of 7
Cable harness of seat
suspension with pin assignment
(1) Cable harness for seat suspension
(2) Socket (cable harness for seat
suspension) (4-pin)
(3) Cable tie
(4) Socket (cable harness for seat
suspension) (3-pin)
(5) Plug (cable harness of seat
suspension) (6-pin)
(6) Socket of cable harness for seat
suspension (18-pin)
(7) Push mount tie with wings
(8) Cable tie with bracket
(9) Connector plug (vehicle) (12-pin)
(10) U-shaped profile
(11) Fuse (Si = 15A)
(12) Plug (cable harness of seat
suspension) (4-pin)
(13) Corrugated pipe support
(14) Right-angle plug (black cable)
(15) Right-angle plug (blue cable)
(16) Plug (cable harness of seat
suspension) (8-pin)
Electrical plug and socket connections:
(A) Electrical connection (3-pin)
between sensor module and cable
harness for seat suspension (1), see
pate 2
(B) Electrical connection (4-polig)
between electromagnet for 2/2 and
3/2 directional valve at the sensor
module and cable harness for seat
suspension (1), see page 2
(C) Electrical connection (18-pin)
between control / air reservoir and
cable harness for seat suspension
(1), see pages 2, 3, 4, 5
(F) Electrical connection (4-pin)
between cable harness for energy
bundle and cable harness for seat
suspension (1), see page 4
(G) Electrical connection between
compressor and cable harness for
seat suspension (1), see page 5
(H) Electrical connection between
compressor and cable harness for
seat suspension (1), see page 5
2857
1
5
7
6
12
10
13
2
3
8
3
4
K
F
H
GF
B
A J
I
C
14
15
8
9
11
13
16

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.1 Overview of components
Page 7 of 7
Electrical plug and socket connections:
(I) Electrical connection (6-pin)
between cable harness for seat
suspension (1) and cable harness
for upper seat part
(J) Electrical connection (8-pin)
between cable harness for seat
suspension (1) and cable harness
for upper seat part
(K) Electrical connection (12-pin)
between cable harness for seat
suspension (1) and cable harness
for vehicle connection
2858
5
9
16
IJK
P1P2P3P4P5P6
P4
P5
P6
P7
P8
P1P2
P3

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.2 Overview of faults – Pointing out possible faults that might occur
Page 1 of 4
This chapter contains notes on possible faults of the seat suspension. The notes and information provided in Chapter 2.3 "Troubleshooting – Locating the fault" are intended to
ease troubleshooting of faults. The upper seat part has been inspected and found to be OK with respect to the faults described here (see Diagnosis in the repair manual for the
upper part of the seat).
Faults caused due to insufficient maintenance or improper repair are not covered here.
Note: The components mentioned above are illustrated in Chapter 2.1 and the functional components are illustrated in the repair manual of the upper seat part, if not stated
otherwise in this text.
After having eliminated a fault in the pneumatic system, the possibly activated emergency programme must be deactivated (Chap. 2.3, inspection step no. 7.1).
Fault description Possible cause Troubleshooting
Seat suspension does not respond when operating the height
adjustment in upward direction.
• Compressor is not active.
• Control / air reservoir is defective.
• Cable harness for seat suspension is defective.
• Air intake valve at the active module is defective.
• Sensor module is defective.
• No voltage.
• Switch for height adjustment
• Switch for seat occupancy detection system
Check compressor (Chap. 2.3, inspection step
no. 3.1).
Replace the control / air reservoir (see Chapter.
3.11).
Check the cable harness for seat suspension
(Chap. 2.3, inspection step no. 5.1).
Check the active module (Chap. 2.3, inspection step
no. 4.1).
Check the sensor module (Chap. 2.3, inspection
step no. 2.1).
Check and, if necessary, replace the fuse, current
path and electrical connections.
See Diagnosis in the repair manual for the upper
seat part.
See Diagnosis in the repair manual for the upper
seat part.

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.2 Overview of faults – Pointing out possible faults that might occur
Page 2 of 4
Fault description Possible cause Troubleshooting
Seat suspension responds after the height adjustment has been
operated, but then returns to its original position.
• Free running is not given due to the webbing in the
sensor module being pinched.
• Sensor module is defective.
• Control / air reservoir is defective.
Fix the webbing in the middle of the retractor (no
contact to the black plastic roller)
Check the sensor module (Chap. 2.3, inspection
step no. 2.1).
Replace the control / air reservoir (see Chapter
3.11).
After the height adjustment the seat lowers, but continues to
vent automatically after unloading the seat suspension (driver
gets off the seat).
• Seat occupancy detection system is defective. See Diagnosis in the repair manual for the upper
seat part
Seat suspension does not respond when operating the handle
for seat height adjustment in downward direction.
• Cable harness for seat suspension is defective.
• Seat occupancy detection system is defective.
Check the cable harness for seat suspension
(Chap. 2.3, inspection step no. 5.1).
See Diagnosis in the repair manual for the upper
seat part
Seat suspension does not respond when operating the handle
for seat height adjustment in downward direction.
• Cable harness for seat suspension is defective.
• Sensor module is defective.
• No voltage.
• Control / air reservoir is defective.
Check the cable harness for seat suspension
(Chap. 2.3, inspection step no. 5.1).
Check the sensor module (Chap. 2.3, inspection
step no. 2.1).
Check and, if necessary, replace the fuse, current
path and electrical connections.
Replace the control / air reservoir (see Chapter.
3.11).

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.2 Overview of faults – Pointing out possible faults that might occur
Page 3 of 4
Fault description Possible cause Troubleshooting
Seat suspension changes its position while driving, deflates and
lowers down.
• Air spring and air distributor are leaky.
• Sensor module is leaky.
• Air hose connections are leaky.
• Air hoses are leaky.
Check the air spring and the air distributor
(Chap. 2.3, inspection step no. 1.1).
Check the sensor module (Chap. 2.3, inspection
step no. 2.1).
Check all air hose connections for air leakage and, if
necessary, replace the defective air hose connection
or seal the leaky connection professionally.
Check all air hoses for air leakage and replace the
defective air hose, if necessary.
It is possible to set the seat suspension to the highest position,
but it does not deflate any longer.
• Sensor module is defective.
• Emergency programme is activated.
Check the sensor module (Chap. 2.3, inspection
step no. 2.1).
Deactivate the emergency programme (Chap. 2.3,
step no. 7.1).
Seat suspension can be lowered, but does not pump up from
the lowest position, while the compressor is running.
• Air spring and air distributor are leaky.
• Air hose connections are leaky.
• Air hoses are leaky.
• Sensor module is leaky.
• Compressor is leaky (return valve).
• Control / air reservoir is leaky.
Check the air spring and the air distributor
(Chap. 2.3, inspection step no. 1.1).
Check all air hose connections for air leakage and, if
necessary, replace the defective air hose connection
or seal the leaky connection professionally.
Check all air hoses for air leakage and replace the
defective air hose, if necessary.
Check the sensor module (Chap. 2.3, inspection
step no. 2.1).
Replace the compressor (see Chapter 3.8).
Check the control / air reservoir (Chap. 2.3,
inspection step no. 6.1).

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.2 Overview of faults – Pointing out possible faults that might occur
Page 4 of 4
Fault description Possible cause Troubleshooting
Seat suspension pumps up and remains in the middle position,
while the compressor is running.
• Sensor module is leaky. Replace the sensor module (see Chapter 3.9).
Seat suspension pumps up automatically (e.g. during
compression and expansion or when getting off the seat);
compressor starts running.
• Short-circuit in the compressor cable (e.g. caused by
abrasion).
• Sensor module is defective.
Check compressor (Chap. 2.3, inspection step
no. 3.1).
Check the sensor module (Chap. 2.3, inspection
step no. 2.3).
After longer operation of the handle for height adjustment in
downward direction when there is no load on the seat (for at
least 6 seconds), no valve switching can be heard.
• Cable harness for seat suspension is defective.
• Seat occupancy detection system is defective.
• Switch for height adjustment is defective.
• Valves in the sensor module are defective.
Check the cable harness for seat suspension
(Chap. 2.3, inspection step no. 5.1).
See Diagnosis in the repair manual for the upper
seat part.
See Diagnosis in the repair manual for the upper
seat part.
Replace the sensor module (see Chapter 3.9).
After having operated the handle for height adjustment in
downward direction when there is no load on the seat, valve
switching can be heard immediately.
• Seat occupancy detection system is defective. See Diagnosis in the repair manual for the upper
seat part
Seat suspension travels up and down and hits the upper and/or
lower end stop.
• Vertical shock absorber is defective.
• Air spring and air distributor are leaky.
• Air hose connections are leaky.
• Air hoses are leaky.
• Sensor module is leaky.
• Active module defective.
Replace the vertical shock absorber (see Chapter.
3.4).
Check the air spring and the air distributor
(Chap. 2.3, inspection step no. 1.1).
Check all air hose connections for air leakage and, if
necessary, replace the defective air hose connection
or seal the leaky connection professionally.
Check all air hoses for air leakage and replace the
defective air hose, if necessary.
Check the sensor module (Chap. 2.3, inspection
step no. 2.1).
Check the active module (Chap. 2.3, inspection step
no. 4.1).

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.3 Troubleshooting – Locating the fault
Page 1 of 15
Preconditions for fault diagnosis for each test:
•The individual functions are activated in compliance with the instructions of the seat operating instructions.
•The electrical system of the vehicle has been inspected and found to be OK in compliance with the vehicle operating instructions.
•The electrical connections (STVB) have been inspected with regard to continuity and corrosion and found to be OK; they have been manufactured properly and are locked, if
possible.
•Cable harness for seat suspension has been inspected with regard to arcing spots and broken leads (kinks) and found to be OK.
•The seat suspension is disconnected (no voltage that might cause a current flow must be applied to the seat suspension).
•Bellows at the upper suspension part removed (see Chapter 3.4) and pressed down.
Notes: •The components stated above are illustrated in Chapter 2.1.
•Descriptions of the work required during the diagnosis can be found in Chapter 3.
•Repeat the inspection after replacement of defective components.
•Assemble the seat after the end of the inspection or before repeating the inspection (e.g. reconnecting electrical connections (STVB)).
1 Inspection of air spring and air distributor
Preconditions for fault diagnosis:
•See “Preconditions for fault diagnosis for each test”.
•Air hoses and air intake and exhaust hose have been inspected with regard to kinks and tightness and found to be OK.
Step
no. Inspect/operate Result/Specified status Troubleshooting
1.1 Check the air spring for abrasion. Visible abrasion, air spring is leaky.
No abrasion.
Replace air spring (see Chapter 3.10).
Proceed with inspection step no. 1.2.
1.2 Apply load to the seat suspension. Air escapes at the air spring.
The air spring is airtight.
Replace air spring (see Chapter 3.10).
Proceed with inspection step no. 1.3.
1.3 Apply load to the seat suspension. Air escapes at the air distributor.
The air distributor is airtight.
Replace the air distributor (see Chapter
3.14).
End of inspection.

Repair manual GRAMMER seat suspension MSG95EAC – November 2012
Material no. 1 277 338
2.3 Troubleshooting – Locating the fault
Page 2 of 15
2 Inspection of the sensor module
Preconditions for fault diagnosis:
•See “Preconditions for fault diagnosis for each test”.
•Upper seat part removed at the seat suspension and put aside.
•The air hose to the sensor module has been inspected with regard to kinks, scoring and tightness and found to be OK.
Step
no. Inspect/operate Result/Specified status Troubleshooting
2.1 Apply load to the seat suspension. Air escapes at the retaining ring of the quick
coupling of the sensor module. The air hose is not
connected correctly.
No air escaped at the retaining ring of the quick
coupling.
Plug the air hose completely into the
retaining ring of the quick coupling (see
Chapter 3.9).
Proceed with inspection step no. 2.2.
2.2 Apply load to the seat suspension. Air escapes at the sensor module.
The sensor module is airtight.
Replace the sensor module
(see Chapter 3.9).
Proceed with inspection step no. 2.3.
2.3 • Disconnect the electrical connection (C) between the control / air
reservoir and the cable harness for seat suspension.
Measuring instructions: Connect the negative line from the
ohmmeter to K11.
• Measure the resistance at the contacts K11 and K14 in the
socket of the cable harness of the seat suspension (STVB C):
K11 (ground) ΩK14 (signal) = 20 MΩ(±
±±
±1%) Proceed with inspection step no. 2.4.
>> 20 MΩ(R → ∞)(interruption) or
<< 20 MΩ(R → 0) (short-circuit)
Proceed with inspection step no. 2.5.