Ohm BMW 540i 1998 E39 Workshop Manual

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General
Torque wrench
A torque wrench is used to precisely tighten threaded fasten-
ers to a predetermined value. Many of the repair procedures
in this manual include BMW-specified torque values
in New-
ton-meters (Nm) and the equivalent values in foot-pounds
(ft-
Ib).
4 Several types of torque wrenches are available. An inexpen-
sive beam-type (top) is adequate but must be read visually. A
ratchet-type (bottom) can be preset to indicate (click) when
the torque value has been reached. They all do the same job,
but offer different convenience features at different prices.
The most convenient ones have a built-in ratchet, and can be
preset to indicate when a specific torque value has been
reached. Follow the wrench manufacturer's directions
for use
to achieve the greatest accuracy.
A torque wrench with a range up to about 150 Nm (1 10 ft-lb) BOIBFNG has adequate capacity for most of the repairs covered in this
manual. For recommended torque values of
10 Nm orbelow,
the English system equivalent is given in inch-pounds (in-lb).
These small values may be most easily reached using a
torque wrench calibrated in inch-pounds. To convert
inch-
pounds to foot-pounds, divide by 12.
Digital multimeter
4 Many of the electrical tests in this manual call for the mea-
surement of resistance (ohms) or voltage values. For safe
and accurate tests of sensitive electronic component and
systems, a multimeter or digital
volt/ohm meter (DVOM) with
high input impedance (at least
10,000Sr) should be used.
Some meters have automotive functions such as dwell and
pulse width that are useful for troubleshooting ignition and
fuel injection problems.
CAUTIOI\C
Vehicle electronic systems may be damaged by the high cur-
rent draw of a test light with a normal incandescent bulb. As
a general rule, use a high impedance digital multimeter or an
LED test light for all electrical testing.

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Lubrication System
To test switch, connect an ohmmeter between terminal in
switch body (arrow) and ground. With engine off, there
should be continuity. With engine running, oil pressure
should open switch and there should be no continuity. Re-
place a faulty switch.
CAUTION-
Keep in mind that low oil pressure may be preventing the
switch from turning the light out
If the light remains on while
the engine is running, check the oil pressure as described
earlier. Do not drive the car until the problem is corrected. The
engine may be severely damaged.
Crankshaft rear main seal replacement requires removal of
the transmission and flywheel.
Crankshaft rear main seal, replacing
(&cylinder)
- Remove transmission. See 230 Manual Transmission or
240 Automatic Transmission.
- Manual transmission vehicles: Remove clutch pressure plate
and disc. See
210 Clutch.
- Remove flywheel. See 210 Clutch or 240 Automatic Trans-
mission.
- Drain engine oil.
4 Remove seal carrier bolts from oil pan (arrows). Loosen all
oil pan bolts.

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Ignition System
- Turn ignition on and check for battery voltage,
If battery voltage is not present,
checlt wire between termi-
nal
15 and the unloader relay. See ELE Electrical Wiring
Diagrams.
- Turn ignition off.
Remove coil and inspect coil housing for hairline
cracks or
leaking casting material. Replace any
cracked or leaking coil.
NOTE-
A leaky coil may indicate a faulty Engine Control Module
(ECM). Check ECM before installing a new coil.
CAUTION-
Note location of coilground straps before coil removal; rein-
stall in the same location.
Use a multimeter to test:
Coil primary resistance at coil terminals.
Sparlt plug connector resistance.
* Compare results to specification in Table c. lgnition coil
resistance.
Table c. Ignition coil resistance
Coil secondary
resistance
Spark plug connector:
Bosch 1 .O I( ohm t 20%
1.8 ir ohm t 20%
Component
Co~l prlmary
resistance
- Replace ignition coil or sparlt plug connector if resistance
readings do not meet specifications.
4 Remove ignition coil to be tested.
Install
BMW special tool 12 7 030 (A) on coil to be tested.
Connect ground jumper between coil mounting point
(B)
and engine ground point (C).
Clip scope high pick-up lead (D) around ignition lead.
Start engine.
Compare scope pattern with diagrams in Oscilloscope
di-
agnostic diagrams.
NOTE-
When replacing ignition coils, ensure that the replacements
Terminal
1 (-) and 15 (+)
are
from the same manufacturer with the same partlcode
numbers. If individual coils with the correct specifications are
not available. all coils should be
re~laced.
Resistance
0.8 ohms

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51 2-4
I Door Windows
/ Anti-trap strip
Power window motors
The window motors are mounted on cable regulators. The
window motor control circuit consists of two wires for operat-
ing the motor in both directions.
The motors are activated by relays in the GM
Ill. The relays
provide either power or ground depending on the direction of
window travel. The GM
Ill controls the polarity based on a re-
quest to run the window from a window switch or a conve-
nience
openinglclosing signal.
Convenience openinglclosing
The GM Iii provides the convenience openlclose feature, pro-
viding control of the power windows (and sunroof) from out-
side the vehicle with the key in the driver's door lock. The FZV
(remote key) provides the same function for window opening
only.
Anti-trap protection is active during convenience closing from
the driver's door lock.
If the GM receives a request to operate convenience closing
or opening for more than
110 seconds, the function is deacti-
vated and a
fault code is stored.
Window anti-trap protection
4 A rubber pressure guard is located at the top edge of each
door frame. It consists of two contact strips that close when
subjected to pressure. When the contact strip closes (for ex-
ample, a hand is trapped between the top of the window and
the door frame), an anti-trap signal is sent to the GM
Ill. The
window immediately (within
10 milliseconds) reverses direc-
tion. This feature does not require
initialization.
The E39 pressure sensor finger guard has a resistance of 3
Kw and it is monitored for open circuits. When pressed, the
monitored resistance changes to
< 1 Kw. if anti-trap protection
becomes faulty the one touch window closing will not func-
tion.
Window anti-trap protection is
only active in the one touch
and convenience close modes of operation. If the window
switch is pulled and held, anti-trap protection will not function.
The anti-trap contact strip has a resistance of
1.2 K Ohm and
it is monitored for open circuits. Faults with the anti-trap sys-
tem will cancel the one touch feature requiring the window
switch be held to close the window.