2001 BMW 525i ECU

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120-1 2
ignition System
Crankshaftspeedsensor
Crankshaft speed sensor, replacing (M52, M52 TU and
M54 engines)
4 Crankshaft speed sensor for 6-cylinder engine is mounted in
the left rear side of the cylinder block below the starter (ar-
row). The sensor reads a toothed pulse wheel mounted to
the end of the crankshaft.
- if the Engine Control Module (ECM) does not receive a signal
from the crankshaft speed sensor during cranking, the en-
gine will not start.
- If the OBD II svstem misfire detection ~rotocol detects a cat- - - ~~
alysr oarnagin; faLlt oJe to a ma I-nclion in crandshafi speeo
sensor components. Ine Check Engine
lignr (Malfuncrion In-
dicator Light or MIL) will be illuminated.
NOTE-
If the crankshaft speed sensor pulse wheel is damaged, the
engine will have to be disassembled down to the crankshaft
to
reolace the wheel.
- Make certain ignition has been turned off.
- Raise car and support in a safe manner.
WARNING -
Make sure the car is stable and well supported at all times.
Use a professional automotive lift orjacltstands designed for
the ouroose.
A floor iaclc is not adequate support.
- Remove under engine splash guard
4 Working underneath starter:
Cut off wire tie securing crankshaft speed sensor harness
connector (arrow) to sensor.
* Disconnect harness connector.
4 Remove sensor mounting fastener (arrow) and remove sen-
sor from cylinder block.
- Installation is reverse of removal, noting the following:
Use a new O-ring when installing sensor.
Be sure wiring is routed in same orientation.
Secure sensor using new wire ties.
Use scan tool to read out and clear ECM fault memory.

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Battery, Starter, Alternator
Water-cooled alternator
The water-cooled alternator, used on 1999 and later M62 TU
engines, is a sealed unit housed inside the engine block wa-
ter jacket. It is cooled via the engine cooling system. It is a
"brushless" sealed unit that cannot be serviced. Maintaining
consistent alternator temperatures increases the life span of
the alternator, and elimination of the alternator cooling fan re-
duces alternator noise
significantly.
The M62 TU water-cooled alternator incorporates load start
reduction. This function is intended to shorten the duration of
engine starting, particularly at low ambienttemperatures. The
current load is limited to
20 amps during starting in order to re-
duce alternator braking torque on the engine. Following the
current limiting phase, full power output is then progressively
reached.
Charging system diagnostics requires special test equip-
ment. If the test equipment is not available, charging system
fault diagnosis can be performed by an authorized
BMW
dealer or other qualified repair shop. See Table a. Battery,
alternator and starter troubleshooting for general electri-
cal component troubleshooting.
Before checking the alternator, make sure the battery is fully
charged and capable of holding a charge. Check that the bat-
tery terminals are clean and tight and the alternator drive belt
is properly tensioned and not severely worn.
NOTE-
Some model require up to 15 second to reacli full alternator
output.
CA UTIOG
If the charge indicator light in the instrument cluster remains
on, the charge warning circuit in the instrument cluster may
be faulty. Check that the ground lead is securely
affached to
the grounding stud on the cylinder head
(A). Replacing the
instrument cluster before repairing the ground lead will both
damage the instrument cluster and cause the failure to
reoccur.

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121-18
I Battery, Starter, Alternator
Alternator, removing and installing
(M62 TU engine, water cooled)
V-8 models produced after 9/98 are equipped with a water
cooled alternator.
CAUTION-
Allow engine to cool before removing alternator as coolant
will
escape from the alternator water jacket.
- Disconnect negative (-) battery cable
CAUTION- Prior to disconnecting the
battew read the battery discon-
nection cautions given in
001 General Warnings and Cau-
tions.
- Remove radiator cooling fan and fan shroud. See 170 Radi-
ator and Cooling System.
- Drain engine cooling system. See 170 Radiator and Cool-
ing System.
- Remove alternator drive belt. See 020 Maintenance.
- Disconnect battery lead (terminal 30 or B+) and two-pin har-
ness connector from front of alternator.
I < Remove bolts securing alternator to water jacket and remove
aling ring
alternator.
NOTE- If necessary, raise car and remove engine compartment
splash shield to access lower alternator mounting bolts.
The upper coolant hose can also
be removed to assist al-
ternator removal.

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Fuel Tank and Fuel Pump
Evaporative system troubleshooting
- Start by accessing diagnostic trouble codes (DTCs) using a
BMW or BMW compatible aftermarket scan tool.
For purposes of OBD
II emissions compliance, the DME
system sets a diagnostic trouble code (DTC) when it de-
tects a leak that is equal or larger than minimum
lealc
sensed by system.
Malfunction Indicator Light (MIL) is illuminated upon sec-
ond recurrence of fault. See OBD On-Board Diagnostics.
- When leak testing, observe following conditions to obtain
plausible results:
Fuel tank
'1, to 'I., full.
0 Vehicle parked for at least 2 hours to allow fuel to reach
room temperature.
Ideal fuel temperature is 10"- 20°C
(50"
- 68" F).
Do not refuel immediately before
lealc test.
- If a leak is detected, check the following areas:
* Fuel filter cap (leaking or off).
Fuel tank ventilation lines leaking at fuel
tank or activated
carbon canister.
i
Tank ventilation valve leaking (in engine compartment).
Fuel level
sensorlfuel pump cap leaking.
Evaporative system component replacement is covered later
in
th~s group in Fuel Tank and Fuel Lines.

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I Fuel Tank and Fuel Pump --
Fuel pressure gauge, installing
(6-cylinder models)
4 Remove fuel rail cover by prying off trim covers (arrows) and
removing nuts.
4 If equipped, remove schraeder valve cap (arrow). Blow fuel
back through feed line using a brief burst of compressed air
(maximum
3 bar or 43.5 psi).
WARNING -
Fuel in fuel line is underpressure (approx. 3 - 5 bar or 45 -
75psi) andmay be expelled underpressure. Do not smoke
or work near heaters or other fire hazards. Keep a fire ex-
tinguisher handy Before disconnecting fuel hoses, wrap a
cloth around fuel hoses to absorb any leaking fuel. Catch
and dispose of escaped fuel. Plug all open fuel lines.
Always unscrew the fuel tank cap to release pressure
in the tank before working on the tank or lines.
4 Attach fuel pressure gauge to BMW special tool 13 5 220
(T-fittlng) or equivalent and attach to schraeder valve.
WARNING -
The fuel pressure gauge must be securely connected to pre-
vent it from
coming loose underpressure.
CAUTION-
When using the BMWspecial tool, use care when turning the
T-handle in to open the schraeder valve. Screw the handle in
just until the schraeder valve opens. Turning the handle in too
far will damage the schraeder valve.
NOTE-
* The schraeder valve must be opened to the fuel pressure
gauge connection. Either remove the valve using a stan-
dard tire valve removal tool or use the BMW special tool
15 5 220.
* The fuel pressure gauge should have a minimum range of
0 to 5 bar (0 to 75 psi).
- For vehicles without the schraeder valve on the fuel rail, at-
tach the fuel pressure gauge in line with the fuel supply line
to the fuel rail.

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Fuel Tank and Fuel Pump
Fuel pressure gauge, installing
(V-8 models)
Remove engine cover by pressing down on pins (arrows) to
release cover locks.
4 Disconnect and remove fuel supply line from lefl side of fuel
rail by sliding
loclting collar in (arrows) and pulling lines
apart.
NOTE-
* ME2 TU and MS43 vehicles (1999 and later models) use a
non-return fuel line with only one line to the fuel
rafl.
BMW uses three styles of fuellfne connections; a one-use
clamp, a locking fitting that uses
BMWspeclal tool 16 1 050
to release, and a quick release sleeve (above) that discon-
nects the line when depressed.
WARNING -
* Fuel In fuel line is under pressure (approx. 3 - 5 bar or 45 -
75psi) and may be expelled underpressure. Do not smoke
or work near heaters or other fire hazards. Keep a fire ex-
tinguisher handy. Before disconnecting fuel hoses, wrap a
cloth around fuel hoses to absorb any
lealiing fuel. Catch
and dispose of escaped fuel. Plug all open fuel lines.
Always unscrew the fuel tank cap to release pressure
in the tank before workina on the tank or lines.
< Install inline fuel pressure gauge.
WARNING -
The fuel pressure gauge must be securely connected to pre-
vent it from coming loose underpressure.
NOTE-
The fuel pressure gauge should have a minimum range of 0
to 5 bar (0 to 75 psi).

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1 Exhaust ~vsteml
NOTE-
The front exhaust manifold must be removed before the rear
manifold.
- Installation is reverse of removal.
Coat exhaust mounting studs with CRC or equivalent cop-
per paste.
Use new gasltets and self-locking nuts.
Tightening torques Exhaust manifold to cylinder head 20 Nm
(15 ft-lb)
Front exhaust pipe to manifold 30 Nm
(22 ft-lb)
Oxygen sensor to manifold 50
Nrn (37 ft-lb)
Exhaust manifolds, removing and installing
(M62 engine)
Always use new retaining nuts and gasltets when removing
and installing the exhaust manifolds.
NOTE-
Access to manifolds is extremely limited. If removing exhaust
manifolds as part of additional engine worlc (such as cylinder
head removal), it may be easier to first remove engine.
- With exhaust system cold, raise and support car for access
to exhaust system.
WARNING -
Do not work undera lifted car unless it is solidly supported on
jaclt stands designed for the purpose. Never worlc undera car
that is supportedsolely
by a jack.
- Remove exhaust system. See Exhaust system, removing
and installing.
- Removing right side exhaust manifolds (cylinder bank 1-4):
Remove heat baffle plate.
Disconnect plug connection to oxygen sensor.
securing exhaust manifolds to head.
Remove manifolds towards bottom.
- Installation is the reverse of removal.
Coat exhaust mounting studs with CRC or equivalent
copper paste.
Use new gasltets and self-loclting nuts.

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- Removing left side exhaust manifolds (cylinder bank 5-8):
- Remove heat baffle plate on left side.
Remove oxygen sensor using
BMW special tool 11 7 030
or similar oxygen sensor socket.
Install
BMW special tools 00 0 200,OO 0 201,OO 0 202,OO 0
204, and 00 0 208 or other suitable engine lifting support
above engine and attach to lifting eye on left head.
NOTE-
The supports on special tool 00 0 208 must rest on the
screws on the fenders.
- Remove nut at top of engine support on left side
- Raise engine at front suspension lug a maximum of 25 mm
(I
.O in).
Release clamping bolt and nut
(arrow) and slide universal
joint off steering gear.
4 Remove nuts securing left exhaust manifold to head,
Raise front of manifold as high as possible past end posi-
tion of steering gear and feed out towards bottom.
- Installation is reverse of removal.
Coat exhaust mounting studs with CRC or equivalent
copper paste.
Use new exhaust gaskets and self-locking nuts.
Install new self-locking nuts on engine mount and steering
shaft bolt.