1999 BMW 540i electrical

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I Battery, Starter, Alternator
- Check for battery voltage at terminal 50 of starter motor with
key in start position. If voltage is not present, check wiring be-
tween ignition switch and starter terminal. Check the EWS
system and other inputs that disrupt terminal
56 to the start-
er. See ELE Electrical
Wiring Diagrams. If voltage is
present and no other visible wiring faults can be found, prob-
lem is most likely in starter motor.
Starter, removing and installing
(6-cylinder engine)
The starter is removed from below. Access to starter bolts is
difficult. Be sure to have the proper tools on hand before pro-
ceeding.
NOTE-
Access to the starter wiring is very limited. Forbetteraccess,
it may be necessary to remove the intake manifold.
- Disconnect negative (-) battery cable.
CAUTIOI\C
Prior to disconnecting the battern read the baltery discon-
nection cautions
in OOlGeneral Cautions and Warnings.
Remove complete air filter hous~ng:
Loosen intake duct hose clamp (A) at throttle assembly.
Loosen clamp and remove idle control hose from intake
duct
(B) and disconnect idle speed control valve electrical
harness connector.
Disconnect electrical harness connector
(C) from mass air
flow sensor.
Remove air filter housing mounting screw (D)
Disconnect vent tube
(E).
Loosen air intake duct clamp (F).
Carefully lift air filter housing out of engine bay.
Disconnect throttle cable.
Raise vehicle and support safely.
WARNING-
Make sure the car is stable and well supported at all times.
Use a professional automotive
lift orjack stands designed for
the purpose. A
floorjaclc is not adequate support
- Working underneath car, remove engine splash shield
- Disconnect fuel lines and harness connectors from retaining
brackets, as necessary.

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130-2
/Fuel Injection
This repair group covers service and repair of the Bosch and
Siemens engine management systems used on
1997
through 2002 E39 models. Additional engine management
service and repair information may also be found in the fol-
lowing repair groups:
0 020 Maintenance
120 Ignition System
160 Fuel Tank and Fuel Pump
610 Electrical Component Locations
OBD On Board Diagnostics
NOTE-
Camshaft position sensor, crankshaft speed sensor and
knoclc sensors are covered in 120 Ignition System.
Table a. Engine management system applications
- - ~ ~
1 ~odellmodel year / Engine IDME system I - I
5281, 1997-1 998 IM52. 2.8 liter ISiemens MS 41 .I I 1
528i. 1999ZO00 1~52 TU, 2.8 liter ]siemens MS 42.0 I I
5251, 2001-2002 1~54, 2.5 liter 1 Siemens MS 43.0 I I
530i, 2001-2002 1~54, 3.0 liter ISiemens MS 43.0
5401 1999-2001 1~62 TU, 4.4 liter l~osch ME 7.2
I
OBI) II software and hardware is incorporated in the engine
management control systems. The
OED II system monitors
components that influence exhaust and evaporative emis-
sions. If a problem is detected, the
OED I1 system stores the
associated fault code and condition.
540i. 1997
4 If vehicle emission levels exceed 1.5 times Federally mandat-
ed criteria, the
OED II system illuminates a malfunction indi-
cator light
(MIL) in the instrument cluster.
For the
E39 cars covered by this manual, three different
MIL symbols were used, depending on year and model.
See illustration.
When faults arise, or if the malfunction indicator lamp (MIL) is
illuminated, begin troubleshooting by connecting BMW ser-
vice tester
DISplus, MoDiC, GTl or equivalent scan tool. The
capabilities of OBD
II software has the potential to save hours
540i. 1998 IM62, 4.4 liter /Bosch M5.2.1
M62, 4.4 liter Bosch M5.2

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Fuel Injection
Warnings and cautions
For personal safety, as well as the protection of sensitive
electronic components, adhere to the warnings and cautions
on the following pages.
WARNING-
Gasoline is highly flammable and its vapors are explosive.
Do not smoke or work on a car near heaters or other fire
hazards when diagnosing and repairing fuel system prob-
lems. Have a fire extinguisher available in case of an emer-
gency
Renew fuel system hoses, clamps and O-rings any
time they are removed.
When working on an open fuel system, wear suitable
hand protection, as prolonged contact
with fuel can
cause illnesses and skin disorders.
* 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.
CAUTION-
- Disconnecting the battery may erase fault code($ storedin
memory Check for fault codes prior to disconnecting the
battery cables. Read the battery disconnection cautions in
001 General Warnings and Cautions.
a Connect and disconnect the DME system wiring and
1 test equipment leads only when the ignition is switched
off.
Wait at least 1 minute after turning off the ignition be-
fore removing the engine control module (ECM) con-
nector. If the connector is removed before this time,
residualpower in the system relay may damage the
control module.
Fuel system cleaners and other chemical additives oth-
er than those specifically recommended by BMW may
damage the catalytic converter, the oxygen sensor or
other fuel supply components.
* Do not connect any test equipment that delivers a 12-
volt power supply to terminal 15 (+) of the ignition coil.
The current flow may damage the ECM. In general,
connect test equipment only as specified by BMW or
the equipment maker.
Only use a digital
multirneter for electrical tests. Only
use an LED test light for
quiclc tests.

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130-6
Fuel Injection
Fuel supply to the injection system is provided by a high pres-
sure electric pump mounted inside the fuel tank. The pump is
powered via the fuel pump relay. If the relay is faulty, the fuel
pump will not run and the engine will not start.
NOTE-
* Fuel delivery volume and fuel pressure are critical to prop-
er operation. Fuel pressure direcfly influences fuel deliv-
ery
Fuel pump relay, fuel pressure and fuel volume tests are
given in 160 Fuel Tank and Fuel Pump.
Relieving system fuel pressure
The fuel system retains fuel pressure in the system when the
engine is off. To prevent fuel from spraying on a hot engine,
system fuel pressure should be relieved beforedisconnecting
fuel lines. One method is to tightly wrap
ashop towel around a
fuel line fitting and loosen or disconnect the fitting. Cleanli-
ness is essential when working with fuel components. Thor-
oughly clean the unions before disconnecting fuel lines.
When system faults are detected, a diagnostic trouble code
(DTC) is stored in the engine control module (ECM). The MIL
also iiluminates if an emissions-related fault is detected
When faults arise, or if the malfunction indicator lamp (MIL) is
illuminated, begin troubleshooting by connecting BMW ser-
vice tester
DISplus. MoDiC, GTI or equivalent scan tool. The
capabilities of OBD
II software has the potential to save hours
of diagnostic time and to help avoid incorrect component re-
placement and possible damage to system components.
CAUTION-
- The tests in this section may set fault codes (DTCs) in the
ECM and illuminate the
MIL. Affer all testing is completed,
access and clear DJC fault memory using an
OED I1 or
BMW compatible scan tool. See OBD On-Board Diag-
nostics.
0 Only use a digital multimeter for electrical tests.
. Relay positions can vary Be sure to confirm relay posi-
tion by identifying the wiring in the socket using the wir-
ing diagrams found in ELE Electrical Wiring
Diagrams.

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Fuel Injection 1
Working in right rear of engine compartment:
Release interior ventilation filter cover latch
(A) and re-
move cover.
Release plastic locking tab
(6).
Rotate duct inward (arrow) to unlock from bulk head and
remove duct.
Release spring
lock (C) to remove lower iilter housing.
Slide filter housing away from inner fender to remove.
- Remove electrical box (E-box) cover fasteners and remove
cover.
NOTE-
OBD I1 fault memory (including an illuminated MIL) can
only be reset using an electronic scan tool. Removing the
connector from the ECM or disconnecting the battery will
not erase the fault
memory.
The BMW-dedicated 20-pin diagnostic linlc connector
(DLC) is in the right rear of the engine compartment.
The 16-pin OBD
I1 diagnostic connector (arrow) is located
inside the car on the lower left dash panel.
ECM relay, testing
Fuses lor ECM In E-bbx 502130488
4 The engine control module (ECM) relay is energized via the
ECM and supplies battery positive
(B+) power to many of the
engine management components and subsystems.
If this re-
lay is faulty, the engine will not start.
Relay positions can vary. Be sure to confirm relay position by
identifying the wiring in the socket using the wiring diagrams
in
ELE Electrical Wiring Diagrams.
NOTE-
The ECM relay is also referred to as the DME main relay.

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Fuel Injection I
Mass air flow (MAF) sensor,
checking and replacing
4 The hot film mass air flow (MAF) sensor (arrow) sends a
varying voltage (approx.
0.5 - 4.5 vdc) to the ECM represent-
ing the measured intake air. The air mass input signal is pro-
duced electronically by the
MAFsensorusing a heated metal
film in the air flow stream.
The ECM relay provides the operating voltage to the MAF
sensor. As air flows through the MAF sensor, the film is
-
cooled. To maintain the film at a constant temperature, addi-
tional heating current is necessary. It is this additional current
that is the basis for the input signal.
If there is no output signal from the MAF sensor, the ECM op-
erates the engine using throttle position and engine rpm in-
puts. A faulty MAF sensor illuminates the MIL.
A faulty MAF sensor can produce the following problems:
Difficult to restart when engine is hot.
Engine starts then stalls.
Engine starts and runs only with accelerator pedal de-
pressed.
Disconnect electrical harness connector from MAF sensor
(arrow).
- Turn ignition on and check for voltage and ground at connec-
tor.
There should be ground at pin
1 and battery voltage at pin
3.
If any faults are found, check for wiring breaks between
MAF sensor and ECM and between MAF sensor and ECM
relay.
NOTE-
Visually inspect the sensor for damage, missing or blocked
screens. The screens affect air flow calibration. Also inspect
the sealing O-rings where the sensor inserts into the air
filter
housing and intake boot. Ensure the pin connections are
clean and tight.
4 Connect a BMW-compatible scan tool or an OBD II generic
scan tool. Check air mass signal (load signal) with the engine
at idle. Raise idle speed and check that load signal changes
with rpm.
CA UTIOI\C
Be sure ignition is OFFbefore disconnecting or reconnecting r
1 DME svstem components. 1

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130-1 2
Fuel Injection
- Disconnect intake air boot from throttle housing. Unbolt throt-
tle housing and lay aside. It is not necessary to disconnect
throttle cable or electrical harness connectors from throttle housing.
- Remove electrical harness connector from IAT sensor.
- Unclip temperature sensor and remove from intake manifold.
- Installation is reverse of removal. Use a new gasket at throttle
housing.
Throttle position sensor (TPS),
testing and replacing
4 The throttle position sensor (arrow) is located on top of the
throttle valve housing and provides the ECM with a voltage
value that represents throttle position (angle) and rate of
movement.
TheTPS is non-adjustable. If the throttle position sensor is re-
placed, the previous 'learned' TPS settings must be cleared
from the ECM using a BMW-compatible scan tool.
If the throttle position sensor signal is defective, afault code is
stored and the
MILis illuminated when OBD II fault criteria are
exceeded. The ECM still operates the engine using the mass
air flow
(MAF) sensor and engine rpm inputs.
- Check throttle position sensor function by disconnecting har-
ness connector and checking continuity across terminals. If
test results are incorrect,
replace throttle position sensor. The
sensor is non-adjustable.
Throttle
~osition sensor testina values -
Terminals Test
values
1 and ground in harness 5 vdc (approx.)
connector, ltey on
1 and 3 at sensor 4.0 itR(appr0x.)
1 and 2 at sensor Throttle
plate rotated from idle to
lull throttle, continuously variable
from 1.0
- 4.0 1tR
CAUTION-
Be sure ignition is OFF before disconnecting or reconnecting
DME svstem components. r

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Fuel Injection
- If idle speed valve is not buzzing, or if idle decreases when
AIC is turned on, stop engine and disconnect harness con-
nector from idle speed valve.
connector
CAUTION-
Be sure ignition is OFFbefore disconnecting or reconnecting
DME system components.
Checlc resistance of valve across valve terminals.
Idle speed control valve resistance
Terminals
1 and 2 20 i-2Q
Terminals 2 and 3 20 C2Q
Terminals 1 and 3 40 C4Q
The idle speed control valve is mounted under the intake
manifold. Accessing the valve is best accomplished by first
removing the air filter housing and the throttle housing.
< Disconnect intake air boot from throttle housing. Unbolt throt-
tle body and lay aside. Do not disconnect throttle cable or
electrical harness connectors to throttle body.
NOTE-
For additional worlcing room, unfasten and lift out the com.
plete air filter housing.
- Working under intake manifold, disconnect electrical harness
connector from idle speed control valve.
Unbolt dipstick tube
bracket (A) from intalte manifold.
- Remove two bolts (B) retaining idle speed control valve to un-
derside of intalte manifold. Remove valve from intalte mani-
fold. Remove hose clamp and disconnect hose.
- Installation is reverse of removal. Use new gaskets when in-
stalling.