1999 BMW 540i electrical

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Lubrication system/
4 Install engine lifting tool at front of engine and raise engine
approximately
5 mm (114 in).
< Remove pinch bolt (arrow) at steering column universal joint
near steering rack. See
320 Steering and Alignment.
- Remove power steering pump, leaving hydraulic lines con-
nected to pump. Suspend pump using strong wire. See
320
Steering and Wheel Alignment.
NOTE-
For better access to power steering assembly, unbolt fluid
reservoir and suspend with wire.
Loosen upper nuts (arrow) in right and lefl engine mounts,
< Remove right and left lower engine mount nuts (arrow)
- On cars with automatic transmission, remove ATF cooler line
brackets from engine oil pan.
- Disconnect electrical harness connector at oil level sensor on
oil pan.

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.
[Lubrication System
< Disconnect electrical harness connector (arrow) at oil level
sensor.
< Remove lower oil pan mounting bolts (arrows)
CAUTIOI\C
If the lowerpan does not separate easily from upperpan, a
few taps with a rubber mallet should break it free. Do
notpry
the oil pan loose.
- When installing oil pan:
Thoroughly clean all old
gasltet material from mating sur-
faces and use a new gasket.
4 Install threaded guide studs at locations marked by arrows
to guide new oil pan
gasltet and oil pan into position and to
prevent damage to sealing lip.
- Install new oil pan mounting bolts (threads coated with
sealer).
Remove guide studs and install remainder of oil pan bolts.
- Remainder of reassembly is reverse of disassembly
- After adding engine oil, start and run engine. Raise engine
speed to 2,500 rpm until oil pressure warning light goes out
(about 5 seconds).
Tightening torques Lower oil pan to upper
oil pan
M6 (8.8 grade) 10 Nm (89 in-lb)
M6 (10.9 grade) 12 Nm (9 ft-lb)
M8 (8.8 grade) 22 Nm (16 ft-lb)
Oil drain plug to oil pan (M12) 25 Nm (18 ft-lb)

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... . . Lubrication sy=
Upper oil pan, removing and installing (V-8)
The engine oil pan removal procedure requires that the en-
gine be supported from the top and the front suspension
sub-
frame be lowered.
- Disconnect negative (-) battery cable
4 Lift hood into assembly position.
- While supporting hood, disconnect support struts.
Open hood
fully and lock in piace by installing bolts
(arrow) in left and right hinges to lock hood in place
4 Remove engine top cover:
- Early version: Pry off caps (arrows) and remove fasteners.
Late version: Depress fasteners (arrows) and lift cover.
4 Remove air filter housing and mass air flow sensor:
Disconnect mass air flow sensor
(A) and intake air temper-
ature sensor
(B) electrical harness connectors.
Remove air filter housing mounting fastener (arrow)
Loosen
intake hose clamps (C and D).
Remove air filter housing with mass air flow sensor.
Remove intake hose from throttle body.

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1 19-1 7
Lubrication System
Disconnect electrical harness connect01
sensor.
. (arrow)
4 Remove lower oil pan bolts (arrows) and pan, oil
level
CAUTION-
If the lowerpan does not separate easily from upperpan, a
few taps with a rubber mallet should break it free. Do not pry
the oil pan loose.
Remove
NC drive belt tensioner.
Remove adjustment bolt
(B).
Remove retaining bolt (A) and remove tensioner from oil
pan.
- Remove power steering pump from engine block, leaving hy-
draulic lines connected. Suspend from chassis using stiff
wire. See
320 Steering and Wheel Alignment.

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Ignition System
This repair group covers component troubleshooting and re-
placement information for the ignition system.
When diagnosing engine management problems, including
on-board diagnostics (OBD
11) fault code analysis, also refer
to these repair groups:
* 130 Fuel Injection
* ELE Electrical Wiring Diagrams
OED On-Board Diagnostics
Special tools
System diagnosis and testing of the ignition system requires
special test equipment.
4 LED test light
(Tool No. Baum
1 1 15)
4 Automotive digital multimeter
4 Primary voltage test harness
(Tool No. BMW 12
7 020)
-
4 Secondary voltage test harness
(Tool No. BMW 12
7 030)

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Lnition switch
4 The positive (+) power supply to the ignition coils comes to
the ignition switch via an unloader relay. When the ignition
switch is turned on, the relay closes, to provide voltage to the
ignition coils. The coils are then actuated at the negative side
by the engine control module.
NOTE-
Schematic diagrams shown are for illustrative purposes only.
See ELE Electrical Wiring Diagrams for engine manage-
ment specific wiring information.
WARNING- Do not touch or disconnect any cables from the coils while
the engine is running or being cranked by the starter:
The ignition system produces high voltages that can be
fatal. Avoid contact with exposed terminals. Use ex-
treme caution when
working on a car with the ignition
switched on or the engine running.
* Connect and disconnect the DME system wiring and
test equipment leads only when the ignition is
OFF
Before operating the starter without starting the engine
(for example when
making a compression test), always
disable the ignition.
4 Knock sensors (arrows) monitor the combustion chamber for
engine-damaging knock. Six-cylinder models (shown) use
two sensors with each sensor monitoring three cylinders.
V-
8 models use four sensors, each monitoring two cylinders. If
engine
knock is detected, the ignition point is retarded by the
ECM.
I Ignition advance Ignition timing is electronically mapped and not adjustable.
The ECM uses engine load, engine speed, coolant tempera-
ture, knock detection, and intake air temperature as the basic
inputs for timing control.
A three dimensional map similar to
the one shown is digitally stored in the ECM.
- The initial ignition point is determined by the crankshaft
speed sensor during cranking. Once the engine is running.
timing is continually adjusted based on operating conditions.

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.-
ignition System
Disabling ignition system
The ignition system operates in a lethal voltage range and
should be disabled any time engine service or repair work is
being done that requires the ignition to be switched on.
The engine management system can be disabled by remov-
ing the DME main relay. The relay is located in the electronics
box (E-box) in the left rear of the engine
compartment, be.
neath the interior microfilter housing.
CAUTION- Relay locations may
vary. Use care when identifying relays.
See
610 Electrical Component Locations.
Checking for spark
CAUTION-
If
a spark test is done incorrecth damage to the Engine Con-
trol Module
(ECM) or the ignition coils may result.
NOTE-
Spark plug replacement is covered in 020 Maintenance.
Check~ng for spark is d~fflcult on englnes wlth d~str~butorless
ignition systems.
Try removing the spark plugs and inspecting for differences between them.
A poor-firing plug may be wet with fuel and/or ~. - ~
black and sooty, but not always. If a coil is not operating, the
engine management system will electrically disable the fuel
injector to that cylinder. The key is to look for differences be-
tween cylinders.
Ignition coil assembly, testing and
replacing
C4 UTION-
Use a digital multimeter for the following tests. I
- Remove plastic engine cover from top of valve cover by pry-
ing off bolt covers and removing cover mounting bolts.
- Raise car slowly while constantly checking position of jack
and car.
- Disconnect harness connector from coil. Connect multimeter
between terminal 15
(+) in connector and ground.
4 Terminal identification are typically molded into connector. In
photo, terminals are from left to right: 1,
4a, 15.

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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