2001 BMW 525i Electrical systems

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- -.
Fuel Injection
SIEMENS MIS 42.0 AND 43.0
When system faults are detected, a diagnostic trouble code
(DTC) is stored in the engine control module (ECM). The MIL
also illuminates
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 tlie
ECM and illuminate the MIL. After all testing is completed,
access and clear DTC fault
memory using an OBD I/ or
BMW compatible scan tool. See
OBD On-Board Diag-
nostics.
Only use a
dgital multimeter for electrical tests.
Relay positions can vary. Be sure to confirm
relayposi-
tion by identifying the wiring in the socket using the wir-
ing diagrams found in
ELE Electrical Wiring
Diagrams.
NOTE-
- OBD I1 fault memory. (including an illuminated MIL! can
only be reset using the special 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
20-pin DLC is discontinued on models after
6/2000.
The 1 &pin OBD I1 diagnostic connector (arrow) is located
inside the car on the lower left dash panel.
The MS
42.0 and MS 43.0 systems manage the following
functions.
- Air:
Idle speed valve
Electronic throttle
Hot film mass air flow (MAF) sensor
Resonance-turbulence intake control
- Fuel:
* Fuel supply
Running losseslnon return
Fuel injection

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-
Fuel Injection
ECM relay, testing
The engine control module (ECM) relay is energized via the
ECM and supplies battery positive
(Bc) power to many of the
engine management components and subsystems. If this re-
lay is faulty, the engine will not start.
NOTE-
The ECM relay is also referred to as the DME main relay
ECM relay powers:
ECM
Ignition coils
* Fuel injection
Evaporative leak detection pump
Idle air actuator
- Camshaft sensors Evaporative emissions valve
Hot film mass air flow sensor
Fuel pump relay
Oxygen sensor heaters
4 Working in right rear of engine compartment:
Release interior ventilation filter cover latch
(A) and re-
move cover.
Release plastic locking tab
(B).
Rotate duct inward (arrow) to unlock from bulk head and
remove duct.
Release spring lock
(C) to remove lower filter housing.
Slide filter housing away from inner fender to remove.
- Remove electrical box (E-box) cover fasteners and remove
cover.
With ignition off, remove ECM relay (arrow) in electronics
box (E-box) at rear of engine compartment, right side.
NOTE-
Relay locations can vary Confirm relay identification by
matching wiring colors and terminal numbers.

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- Fuel Injection
ECM relay, testing
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.
CAUTIOI\C
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.
ECM relay powers:
* ECM
Ignition coils
Fuel injection
Evaporative leak detection pump
(5.2.1 only)
Idle air actuator
Camshaft sensors Evaporative emissions valve
Hot film mass air flow sensor
Fuel pump relay
Oxygen sensor heaters
4 Working in right rear of engine compartment:
Release interior ventilation filter cover latch
(A) and re-
move cover.
Release plastic locking tab
(B).
Rotate duct inward (arrow) to unloclc from bulk head and
remove duct.
0 Release spring lock (C) to remove lower filter housing.
Slide filter housing away from inner fender to remove.
- Remove electrical box (E-box) cover fasteners and remove
cover.

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340-8
1 Brakes
Brake bleeding is usually done for one of two reasons: either
to replace old brake fluid as part of routine maintenance or to
expel trapped air in the system that resulted
from opening the
brake hydraulic system during repairs.
Read the
Warnings listed below before beginning the bleed-
ing procedure an on any
E39 car. If air enters the ACS or DSC
hydraulic unit, the factory BMW Service Tester MUST be
used in conjunction with a bralte pressure bleeder before the
vehicle is driven.
The BMW
ServiceTester (DISpluslGT1iMoDiC) must be
used to bleed the braltes if:
Any hydraulic brake system components are replaced, in-
cluding bralte lines.
Air has enter the
ABSIASC or ABSlDSC hydraulic unit.
WARNING -
* The ASC and DSC systems use electronic controls and a
sophisticated hydraulic unit Once air enters the hydraulic
unit, it is very difficult to remove using traditional methods.
For this reason, pressure
brake bleeding should be done
in conjunction with the BMW
Sewice Tester (DIS-
plus/GTl/MoDiC). The tester electrically cycles the hy-
draulic unit solenoids in the hydraulic unit while
pressurized brake fluid is forced through the system.
When flushing the brake fluid from the system, use ex-
treme care to not let the
brale fluid reservoir run dry If
air enters the hydraulic unit, the BMW Service Tester
MUST be used to bleed the brale system before the
vehicle is driven.
Always use new brake fluid from an unopened container. It is
important to bleed the entire system when any part of the hy-
draulic system has been opened. Be sure to have the special
equipment needed before beginning the job.
When bleeding the
braltes, start atthe wheel farthest from the
master cylinder and progress in the following order:
right rear brake
left rear brake
* right front brake
left front brake

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1 Brakes
- Remove precharge pump mounting bracket fasteners and re-
move pump.
- Installation is reverse of removal, noting the following:
Be sure to replace rubber pump mounts if damaged
01
worn.
Bleed brakes as described earlier.
Tightening torque Brake line
to precharge pump 18 Nrn (13 ft-lb)
DSC pressure sensor (1 999 - 2002 models)
On 1999 and later DSC systems, the DSC pressure sensor is
screwed into the DSC hydraulic unit (right rear of engine com-
partment).
WARNING-
* €39 cars require special BMW service equipment to prop-
erly bleed the brakes. Removal of the
DSCpressure sensor
is not recommended unless this equipment is available. For
safety reasons, the brake system on cars with ABS must be
bled using the procedures described in this repair group.
Switch off ignition and remove
key to male sure brake
system cannot be activated.
- Disconnect electrical harness connector at switch.
- Use BMW special tool 34 5 160 to remove and install sensor.
Inspect threads and sealing surfaces for damage.
* Work quicltly to avoid excessive brake fluid leakage.
Tightening torque
Pressure sensor
to hydraulic 19 Nrn (14ft-lb)
unit
- Reconnect harness connector
- Bleed front brakes as described earlier.
- Press on brakes and check for leaks at sensor.
- Turn on ignition and firmly depress brake pedal. Check that
DSC warning light does not come on.

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51 5-2
/Central Locking and Anti-Theft
This section covers repair information for door, trunk and car-
go compartment locks, central locking, electronic
immob~liza-
tion (EWS) and anti-theft alarm (DWA).
€39 cars are equipped with sophisticated self-diagnostic elec-
trical systems. When experiencing malfunctions relating to
central locking. EWS or anti-theft systems, start the diagnosis
process using the
BMW service tester DIS, GT 1, MoDiC or
equivalent scan tool. An advanced diagnostic scan tool can
usually pinpoint electrical faults quickly and safely.
Additional electrical information can be found in:
610 Electrical Component Locations
ELE Electrical Wiring Diagrams
Central locking in E39 vehicles controls the door
locks, trunk
or tailgate lock and fuel filler flap lock. The control module for
the Central Body Electronics system (ZKE
Ill), lknown as the
General Module (GM
Ill), controls central locking.
ZKE
Ill manages the following central locking related func-
tions:
Central locking
* Keyless entry
Key memory
Power trunk release
Electric opening of tailgate
DWA alarm system
Diagnosis
General Module
4 The General Module (GM) (arrow) is responsible for the op-
eration of central body electronics. The GM is located behind
the glove compartment.
Based on input information, the GM uses internal transistors
to switch current flow (providing voltage or ground) through
circuits and actuators. Actuators are the final controlling de-
vices used by GM to operate or control various output func-
tions such as relays and motors.
The accompanying schematic, Central locking inputs and
outputs, illustrates the GM central locking system.

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4 INDEX
Door window anti-trap
512-4 convenience openinglclosing 512.4
regulator and motor 512-1 1
service
512-5 switches 512-3
see also Switches
Double
VANOS see VANOS
Drive
axle
CV joint 331-15 CV joint boot 331-15
rernovinglinstalling 331-14
Drive belt
see Maintenance
Driveabiiity troubleshooting
100-4
Driveaway protection
see EWS (eiectronic immobilization)
Driveshaft aligning
260-7
center bearing, replacing 260-12 CV joint, replacing 260-14
itex-disc, replacing 260-1 1
iront centering guide, replacing 260-13
rernovinglinstailing 260-6
lroubleshooting 260-3
U-joint 260-3
DSC
see Braires
DTC (diagnostic trouble code)
OBD-8
DWA
see Anti-theft alarm
ECM (engine control module)
see 130 under appropriate
iuei
injection system
ECT (engine coolant temperature)
sensor see 130 under appropriate
iuei
injection system
EDK adaptation
130-69
MS 43.0 130-35
EHC see Electronic iieigiit control (EHC)
Electric cooling fan
see Cooling system, cooling
fan
see also Cooiing system, eiectric fan
Electrical switches
see Switches
Electrical system abbreviations
600-14 bus System 600-4
component location table 610-3
components
photos
610-36
Sport Wagon 610-81 engine 121-2
troubleshooting 600-15
voltage and polarily 600-5 wire color codes 600-12
wiring diagrams 600-12
Electrical wiring diagrams
ELE-1
Eiectricaliy heated thermostat
(characteristic map)
170-4
Eiectronic height control (EHC)
300-8, 330-44
Eiectronic immobilization
see EWS (electronic immobilization)
Eiectronics box
(E-box)
610-37
Emergencies
010-18
Emergency brake see
BraBes, parking brake Engine
see also Cylinder head and valvetrain
applications
100-2
compression, testing 113-5
cooling see Cooiing system
crankshaft front oil seai
see Crankshaft oil seals
cyiinder leak-down test 113-8
diagnostic testing 113-1
drive belts
see Maintenance
driveability troubleshooting
100-4
engine management systems 100-2
see also Ignition
see also Fuel injection
fuel supply
130-6
ground connections 100-5
see also 61 0 identilying ieatures 100-3
lubrication svstem
see
~ubricetion system
mount
on-board diagnostics
OBD-I
oxygensensor
see Fuel injection
see also Exhaust system
Dreventive maintenance
see Maintenance
removal/installation
Engine control module (ECM)
see 130 under appropriate iuel
injection system
Engine cooiant temperature (ECT)
sensor see 130 under appropriate iuel
injection
system
Engine cooling fan
see Cooiing system, electric fan
Engine hood
41
0-6 raising to service position 410-6
Engine troubleshooting
see Engine, driveability troubleshooting
EVa~oratiVe control svstem
160-3 see also 130 under aDDroDriate iuel
injection system
Evaporator see
NC
Evaporator temperature sensor see
NC