1998 BMW 540i Ac system

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51 2-2
I Door Windows 1
This repair group covers door glass, window regulator and
power window motor repair information.
CA U JIO&
All E39 models are equipped with side-impact airbags in the
front doors. Some models are also equipped with
airbags in
the rear doors. Be sure to read the
airbag warnings and cau-
tions in 721
Airbag System (SRS).
Electric window switch replacement is covered in 612
Switches.
The windshield, rear window, fixed rear doorglass, and cargo
compartment glass (Sport Wagon only) are bonded using
special adhesives and tools. It is recommended that bonded
glass replacement be done by an authorized
BMW service fa-
cility or an automotive glass installer.
Special tools
Some window repair operations require special tools.
Power windows
- Power window features in E39 models include:
Control of the front and rear door window motors is carried
out directly by the General Module (GM
Ill).
One-touch operation in both directions on all four windows.
Cable type window regulator used for all door windows.
. Anti-trap protection provided by pressure sensitive finger
guard.
Right front and each rear door has a single window switch
located in door handle trim.
Rear door window switches can be deactivated by press-
ing child lock-out switch in the driver's window switch block.
Convenience closinglopening of the windows from driver's
loci( cylinder or convenience opening only from remote un-
lociting feature (FZV) remote key.
Window (FZV) operation can be owner customized with
Car Memory function. See 515 Central Locking and Anti-
Theft.
After ignition is switched off, electric windows can be oper-
ated until a door is opened or until
I6 minutes has elapsed.
The GM
IiI bases window motor end position on current
draw (load). There is a maximum window motor run time of
6 seconds. The motor is then switched off even if the end
position load sensor fails.

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51 2-3
Door Windows
Window switches
4 The push type window switch provides the GM Ill with a cod-
ed ground signal. Holding a switch at the first detent provides
a single ground signal on one wire requesting the GM
Ill to
open the window. When released, the ground signal is re-
moved and the window motor stops.
- Momentarily pushing the switch to the second detent and re-
leasing provides an additional ground signal on the second
wire requesting "one touch mode". The GM
Ill lowers the win-
dow automatically until it reaches the end position. Each win-
dow has four positions, two each for the standard mode of
operation and two for the one-touch mode. All window oper-
ation signals are digital inputs to the door modules and GM
111.
- The switch functions in the same manner for window closing
but the ground signal sequence is reversed.
4 Window switch positions.
1. Off
2. Open
3. One touch open
4. Close
5. One touch close
Rear window child lockout switch
4 The rear window child lockout switch (arrow) is incorporated
in the driver's window switch block in
leit front door arm rest.
When activated, it provides a constant ground signal to the
GM
Ill, preventing the windows from being operated from the
rear door switches.
- The lockout switch ground signal is overridden by the GM Ill
if a passive safety system (MRS) crash signal is received.

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Door windows1
Window motor limit stop function
If repeated window activation (upldown cycles) exceeds one
minute, the
GM Ill deactivates the internal relays and disre-
gards any further
upldown requests. The GM Ill provides mo-
tor activation after a short duration but not for the full one
minute monitoring cycle.
The
GM Ill monitors the number of times a window motor is
activated. It counts each cycle and stores the number in
memory. Afler the stop function limit is reached and the win-
dow motor is deactivated, the
GM Ill slowly reverses the
stored count of activation until the stored number equals
0,
thus allowing the window motor to cool down.
WARNING-
* Always wear hand and eye protection when working with
brolen glass.
If a window is brolen, all of the glass bits should be
vacuumed out of the door cavity. Use a blunt
so-ewdi-iv-
er to clean out any remaining glass pieces from the
window guide rails.
When servicing the door windows, the harness con-
nector to the window regulator should always be dis-
connected to prevent pinching fingers in the moving
window mechanism.
Sedan and Sport Wagon doors are similar. Use the following
procedures for window service on these models.
WARNING-
E39 cars are iitted with side-impact airbags in the front
doors. Some are equipped with
airbags in the rear doors
as well. When
servicing the door windows on cars with
side-impact airbags, always disconnect the negative
(-)
battery cable. See 721 Airbag System (SRS) for cau-
tions and procedures relating to the
airbag system.
* Prior to disconnecting the battery, read the battery dis-
connection cautionsgiven
001 General Warnings and
Cautions.

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51 2-8
Door Windows
Door window, adjusting
Whenever the door window or window regulator is removed,
window adjustment should be checked. The glass should
contact the top of the window squarely and should seat
against the window seal uniformly.
NOTE-
If the window does not contact the window seal uniformly,
wind noise or water infiltration may result.
- Remove door panel as described in 411 Doors.
- Disconnect negative (-) cable from battery. Remove airbag
unit and vapor barrier from door. See 721 Airbag System
(SRS).
WARNING-
Prior to disconnecting the batteg read the battery discon-
nection cautions given in
001 General Warnings and
Cautions.
Longitudinal adjustment
- Adjustments are made with window in open position.
Loosen window guide rail mounting nuts (arrows), but do not
remove.
Slide window glass in longitudinal direction to adjust
Tighten guide rail nuts.
Tightening torque
Window regulator guide rail to door
10 Nrn (89 in-ib)

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Door Windows
Tilt window glass carefully inside door cavity and lift out of
door.
Installation is reverse of removal.
Replace plastic window retainers once glass is inside door.
Use new mounting bolts when reinstalling side-impact
air-
bag to door.
Adjust window as described earlier,
Sedan and Sport Wagon doors are similar. There are two win-
dow rails in each front window regulator, only one in the rear.
Otherwise the front and rear regulators are similar.
WARNING-
E39 cars are Wed with side-impact airbags in the front
doors. Some are equipped with
airbags in the rear doors
as well. When servicing the door windows on cars with
side-impact airbags, always disconnect the negative
(-)
battery cable. See 721 Airbag System (SRS) for cau-
tions and procedures relating to the
airbag system.
Prior to disconnecting the battery, read the battery dis-
connection cautions given at the front
001 General
Warnings and Cautions.
NOTE-
Because window operation is electronically controlled, a win-
dow motor does not have mechanical endpositions. For this
reason it can be removed and installed with the window in
any position and does not need reinitialization.
Front window regulator removing and
installing
NOTE-
BMW recommends removing the window regulator and mo-
tor as one unit, then separating the two on the bench.
- Remove front door panel as described in 411 Doors.
- Disconnect negative (-) cable from battery, then remove air-
bag unit and vapor barrier from door. See 721 Airbag Sys-
tem (SRS).

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Door windows1
Rear window regulator, removing and
installing
NOTE-
BMW recommends removing the window regulator and mo-
tor as one unit, then separating the
two on the bench.
- Disconnect negative (-) cable from battery
- Remove door panel as described in 411 Doors
- Remove airbag unit and vapor barrier from door. See 721
Airbag System (SRS).
- Disconnect window from window guide rail as described in
Door window, removing and installing. Do not remove
window from door.
Push window up and use wedge to
hold in position.
Loosen fastener (arrow) and slide window regulator up and
out of mount.
Disconnect wiring harness connector (A) and remove fasten-
ers
(6).
Remove window regulator and motor through opening in
door.
- Installation is the reverse of removal.
Be sure to route wiring harnesses to keep them away from
moving window mechanism. Use new wire ties as neces-
sary.
Tightening torques
Window motor to regulator
5 Nrn (44 in-ib)
Window regulator to door
Window to guide
8 Nrn (71 in-lb)
8 Nrn (71 in-lb)

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I lnterior Trim
This repair group covers interior trim removal and installation
procedures.
- Refer to the following repair groups for additional information:
250 Gearshift Linkage
41 1 Doors (interior door panels)
@ 612 Switches
620 Instruments
640 Heating and Air Conditioning [IHKA control panel!
650 Radio
721 Airbag System (SRS)
lnterior trim repairs
lnterior trim and finish panels are clipped or screwed into
place. Many of the trim retaining clips are designed
to be used
only once. When removing trim that is held in place with clips,
it is a good idea to have spare clips on hand before beginning
the job.
WARNING-
Special precautions must be observed when servicing the
BMWSupplementai Restraint System (SRS). Serious inju-
ry may result if system service is attempted by persons un-
familiar with the BMW
SRS and its approved service
procedures. BMW
speciiies that all inspection and service
should be performed by an authorized BMW
dealer.
Before performing any work involving airbags, discon-
nect the negative
() battery cable. See 721 Airbag
System (SRS).
Airbags contain a back-uppowersupply within the SRS
control module. A
5 second discharge period should be
allowed after the battery cable has been disconnected.
CAUTION-
* When working on electrical switclies or lights, always dis-
connect the negative
(-) cable from the battery and insu-
late the cable end to prevent accidental reconnection.
a Prior to disconnecting the battery, read the battery dis-
connection cautions given in
W1 General Warnings
and Cautions.
To prevent marring the trim when working on interior
components, work with plastic prying
tools or wrap the
tips of screwdrivers and pliers with tape before prying

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Interior ~riml
Upper dash assembly, removing and
installing
- Remove lower dash assembly. See Lower dash panel as-
sembly, removing and installing.
I I 4 Remove instrument cluster fasteners (arrows) and swing
cluster out to remove.
Disconnect wiring harnesses from instrument cluster.
4 Remove A-pillar (windshield pillar) trim on left and right sides
by prying out
HPS cover (arrow).
- Remove screws beneath covers.
- Remove passenger side airbag. See 721 Airbag System
(SRS).