1997 BMW 540i Harness

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170-25
Radiator and Cooling system]
< Disconnect expansion tank:
Remove expansion tank bleed screw and support clip
(A)
Loosen hose clamp (6) and disconnect coolant hose from
expansion tank.
Disconnect harness connector from coolant level sensor
(C).
Push top of expansion tank toward engine and disconnect
bleed hose.
Lift expansion
tank to free it from lower mounts, then lift
straight up to remove.
- Installation is reverse of removal, noting the following:
Fill radiator and cooling system as described earlier. See
Coolant, draining and filling (6-cylinder models) or
Coolant, draining and filling
(V-8 models).

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180-6
Exhaust System
Exhaust manifolds, removing and installing
(M52 TU and M54 engines)
I Exhaust manifolds with converters I 4 The exhaust manifolds incorporate the catalytic converters.
Two precatalyst and two post-catalyst oxygen sensors are
mounted in the exhaust manifold assembly.
Under normal conditions, the catalytic converters do not re-
quire replacement unless damaged. Always use new retain-
ing nuts and gaskets when removing and installing the
exhaust manifolds.
I\
1 4 Using engine support equipment (BMW special tools 00 0
200. 00 0 201. 00 0 202.00 0 204.00 0 208 or equivalent).
connect to
lifting eye on front of engine. Rhise engine approx.
/I 1
5 mm (IH in).
With exhaust system cold, raise and support car for access
to exhaust system.
WARNING-
Do not worlc undera liftedcar unless it is solidly supported on
jack stands designed for that purpose. Never worlc under
a
car that is supported solely by a jaclc.
in order to avoid damaging oxygen sensors:
- Detach oxygen sensor harness connectors,
Remove oxygen sensors from exhaust manifolds as de-
scribed later in this group.
Unbolt and remove secondary air
checkvalve and pipe from
right front of cylinder headlexhaust manifold.
Working underneath car, unbolt front exhaust pipes from ex.
haust manifolds.
With engine supported from above, remove right engine
mount
bracket and right engine mount (arrow).
Loosen and remove nuts from exhaust manifolds and remove
manifolds. Discard nuts and gaskets.
CA UTIOG
Take care tliat the front and rear oxygen sensor connectors
are not mixed up.
-

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-- -
Exhaust System
Oxygen sensors (precatalyst), replacing
(M52 TU and M54)
The precatalyst oxygen sensors are installed at the top of the
exhaust manifolds.
WARNING-
Allow components to cool before servicing.
- Using BMW scan tool DlSplus (Diagnostic Information Sys-
tem) or equivalent, read out and clear ECM fault codes.
Working at right side of engine above exhaust manifolds,
remove front or rear oxygen sensor harness connector
(arrows) from bracket, then separate plug.
NOTE-
In photo, secondary air pump has been removed for clarity.
Remove oxygen sensor using special oxygen sensor
removal socket.
Installation is reverse of removal
New sensor threads come coated with anti-seize paste.
If reusing a sensor, apply thin coat of anti-seize paste to
threads only. Do not contaminate tip of sensor with paste
or lubricants of any sort.
Install harness and connector in original location.
Tightening torque
- -.
Oxygen sensor to manifold 50 Nm (37 ft-lb)
Oxygen sensors (post-catalyst), replacing
(M52 TU and M54)
The post-catalyst oxygen sensors are installed at the rear of
the catalytic converters.
WARNING-
Allow components to cool before servicing
- Using BMW scan tool DlSplus or equivalent, read out and
clear ECM fault codes.
- Remove large cover from above fuel raillintake manifold.

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Exhaust System
Label and disconnect sensor harness connectors (arrows).
CAUTlOI\C
Label connectors so that front and rear connectors are not
mixed up.
- Detach harness from guides and brackets.
- Remove oxygen sensor from exhaust manifold using special
tool
11 7 030 or equivalent.
- Installation is reverse of removal
New sensor threads come coated with anti-seize paste.
If reusing old sensor, apply thin coat of anti-seize paste to
threads only. Do not contaminate tip of sensor with paste
or lubricants of any sort.
Install harness and connector in original location.
Tightening torque
Oxygen sensor to manifold 50 Nm (37 ft-lb)
Oxygen sensor, replacing
(M52 and M62 engine)
The sensors are installed at the front and rear of the catalytic
converters.
I WARNING- I
I Allow components to cool before servicing. I
Using BMW scan tool DlSplus or equivalent, read out and
clear
ECM fault codes.
Detach harness from guides and brackets.
Remove oxygen sensors (arrows) from exhaust using spe-
cial tool
ll 7 030 or equivalent.
Installation is reverse of removal
New sensor threads come coated with anti-seize paste.
If reusing a sensor, apply thin coat of anti-seize paste to
threads only. Do not contaminate tip of sensor with paste
or lubricants of any sort.
Install harness and connector in original location.
Tightening torque
Oxvaen sensor to manifold 50 Nm (37 it-lb)

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Tool for bleeding clutch hydraulics (Tool No. 21 5 030)
21 5 030 I
The clutch is hydraulically actuated by the master and slave
cylinders. With the self-adjusting clutch
(SAC), clutch disc
wear is automatically taken up through the self-adjusting
pressure plate springs, making pedal feel consistent through-
out the life of the clutch.
A soft or spongy feel to the clutch pedal, long pedal free-play,
or grinding noises
from the gears while shifting can all indi-
cate problems with the clutch hydraulics. In these circum-
stances it is best to
star? with a clutch fluid flush, followed, if
necessary, by replacement of the hydraulic parts.
NOTE-
The clutch hydraulic system shares the fluid reservoir and flu-
id with the brake hydraulic system.
Clutch hydraulic system,
bleeding and flushing
If the clutchlbralte fluid is murky or muddy, or has not been
changed within the last two years, flush the system and
change the fluid. Flushing the old fluid from the clutch lines is
done using a bralte system pressure bleeder.
- Remove brake fluid reservoir cap. Using a clean syringe, re-
move brake fluid from reservoir. Refill reservoir with clean
DOT
4 bralte fluid.
Worlting inside engine compartment, remove left
interiorven-
tilation filter housing:
Release 3 plastic taps
(A) on duct. Earlier models use a
single release latch.
Rotate duct inward to remove.
Disconnect electrical harness to hood position switch.
Remove filter housing cover.
Release spring lock
(B) on interior ventilation housing and
remove housing.

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21 0-6
1 Clutch
Hydraulic system, bleeding
(using
BMW special tool 21 5 030)
4 Working underneath transmission, remove slave cylinder
mounting nuts (arrow) from clutch housing and remove
cylinder. Leave fluid line attached.
4 Use BMW special tool 21 5 030 to press slave cylinder push-
rod completely into slave cylinder.
Hold slave cylinder so that bleeder valve is at highest point.
Open bleeder valve and allow brake fluid to expel until
clean fluid comes out, free of air bubbles.
* Close bleeder valve and disconnect pressure bleeding
equipment from fluid reservoir.
Slowly unscrew and detach special tool 21
5 030 from
slave cylinder.
CAUTION-
Do not remove tool if hydraulic system is pressurized.
- Reinstall slave cylinder.
Tightening torque Slave cylinder to transmission case
22 Nm (1 6 ft-lb)
- Slowly operate clutch pedal about 10 times. Fill reservoir with
clean fluid as necessary.
Clutch master cylinder, replacing
The clutch master cylinder is mounted to the pedal assembly
directly above the clutch pedal.
Working inside engine compartment, remove left interior
ventilation filter housing:
Release 3 plastic taps
(A) on duct. Earlier models use a
single release latch.
Rotate duct inward to remove
Disconnect electrical harness to hood position switch.
Remove filter housing cover.
Release spring
loclc (B) on interior ventilation housing and
remove housing.

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21 0-7
Clutch
- Remove brake fluid reservoir cap. Using a clean syringe.
remove brake fluid from reservoir to below level of clutch
hydraulic supply hose.
- Detach clutch hydraulic supply hose from brake fluid reser-
voir. Plug reservoir outlet and hose.
4 Remove lower dash trim panel fasteners (A) and (B).
Lower trim panel and disconnect wiring harnesses on back
side of panel.
Remove trim panel.
4 Working under dash, remove clutch master cylinder pushrod
retaining clip (arrow) and pin from clutch pedal.
4 Remove master cylinder mounting bolts (arrows)

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21 0-8
Clutch
4 Remove hydraulic line locking clip (1) and pull line (2) off
master cylinder.
CAUTION-
. To prevent brake fluidspill, wrap clutch master cylinder with
shop rags when removing hydraulic fluid lines from master
cylinder.
* Brake fluid damages paint andstains carpets. Clean off
any brake fluid on or
in the car immediately.
- Remove master cylinder with supply hose
4 Remove switch module from master cylinder.
Press locking button
(A) to release harness connector.
Pull harness connector
(8) off switch module.
Use screwdriver to lever
off switch module (C).
- Installation is reverse of removal.
CA UTlON-
Switch module must snap firmly into place on the master cyl-
inder during installation.
Tightening torques
Clutch master cylinder to pedal cluster
10 Nm (89 in-lb)
Fluid line
to master cylinder or slave cylinder 17 Nm (13 ft-lb)
- Fill fluid reservoir with clean fluid. Bleed clutch hydraulics as
described earlier.
Clutch slave cylinder, replacing
4 Working inside engine compartment, remove left interiorven-
tilation filter housing:
Release
3 plastic taps (A) on duct. Early models: release
latch.
Rotate duct inward to remove.
Disconnect electrical harness to hood position switch.
Release spring lock (B) on interior ventilation housing and
remove housing.
- Pinch off brake fluid supply hose to clutch master cylinder us-
ing BMW special tool
13 3 01 0 or equivalent hose clamping
tool.