BMW X5: Troubleshooting
CONTENTS OF ENGINE ELECTRICAL SYSTEM GENERAL
General Information -> Working on ignition system.
-> Removing and installing electronic control units.
-> Welding work (overload protection of control units).
-> Disconnecting and connecting battery.
-> External jump-starting aid.
INSTRUCTIONS FOR DISCONNECTING AND CONNECTING BATTERY
Observe safety instructions for handling vehicle battery.
Before disconnecting battery:
Turn off the ignition and other electrical loads/consumers to prevent
sparking when reconnecting.
NOTE: If the ignition is not turned off when the battery is
disconnected, fault memories
may be set in some control units.
IMPORTANT:
- There is a danger of mixing up battery leads: If the battery
positive and
negative leads are the same color and you are in doubt, follow the polarity
to the battery, then mark and cover the leads.
- On vehicles with radio code: After disconnecting the battery, the
radio
code must be re-entered. Therefore obtain the radio code card from the
customer beforehand. Note stored stations and restore them after
connecting the battery.
- Stored settings of the on-board computer and clock will also be
lost.
- All available central keys must be recoded for cars with first
generation
infrared transmitter locking systems.
General notes on disconnecting battery:
- Do not disconnect battery leads and leads from alternator and starter
motor while engine is running.
- Cars with IBS on battery negative terminal:
Do not under any circumstances pull/lever off pole shoes by force.
Do not under any circumstances release socket-head cap screw of IBS.
- Detach terminal of battery negative lead from car battery and second
battery if fitted. Cover battery
negative terminal(s) and secure.
- When work is carried out on the electrical system, faults may be caused
in the fault memories of some
control units when the battery is connected.
- When installing battery terminal: Tightening torque 61 21 1AZ.
After connecting battery:
IMPORTANT: The scope of application of some systems may be restricted
after a power
supply interruption. Likewise, individual settings may be lost.
Settings or activations must be carried out, depending on the equipment
specification.
Example:
- Vehicles with automatic engine start-stop system (MSA): MSA
function is
active only after learning period (vehicle must not be woken for a period
of 6 hours) > if necessary, notify customer of the situation.
- E46 (AWD)/ E53/ E83: Carry out steering angle sensor adjustment.
- If necessary, carry out adjustment of active front steering.
- If necessary, activate sliding sunroof.
- If necessary, activate power windows.
- If necessary, activate mirror with compass.
Please refer to the Program user documentation for further information
on
vehicle-specific activation.
Vehicles with a two-battery system
Starter and equipment batteries
A two-battery system has a starter battery circuit and an equipment battery
circuit. A secondary control unit
monitors both battery circuits. Depending on the situation, the battery circuits
are connected to or isolated from
the secondary control unit via an isolating relay.
Two AGM batteries, whose design and properties are described in AGM batteries,
are used as a storage battery.
IMPORTANT: These batteries must not under any circumstances be charged
with a voltage in
excess of 14.8 V. Rapid programs must not be used either.
Receiving/giving starting assistance via jump start terminal
The engine can be jump-started with an external voltage supply via the jump
start terminal on the right side of
the engine compartment.
NOTE: The starter battery is isolated from the alternators when the
engine hood/bonnet
is open.
Giving starting assistance via the jump start terminal is thus limited by the
capacity of the starter battery when
the engine hood/bonnet is open.
Charging starter and equipment batteries via jump start terminal
The starter battery is charged as a matter of priority with a charger connected
to the jump start terminal. The
voltage at the starter battery is the decisive factor in determining whether the
equipment battery is also included
in the charging operation. The secondary control unit automatically detects a
charging operation at a charging
voltage at the starter battery of > or = 13.5 V. The isolating relay is closed
and thus the equipment battery is
connected in parallel. Both batteries are now charged.
Prerequisite:
- Terminal 61 inactive
- Terminal 15 inactive
If terminal 15 becomes "active" during the charging operation, the isolating
relay is opened immediately and
again only the starter battery is charged.
NOTE: When the engine hood is open, the isolating relay is also opened
in normal
operation when the engine is running.
A special mode can be set by means of diagnosis for workshop/garage
operation. The isolating relay is closed from terminal R in this operating mode.
This mode is automatically reset once a distance of 5 km has been driven.
Trickle charging
The increased closed-circuit current consumption can be compensated for via
the jump-start connection point
with the aid of the "Acctiva easy" battery trickle charger.
INSTRUCTIONS FOR REMOVING AND INSTALLING ELECTRONIC CONTROL UNITS
IMPORTANT:
- Disconnecting the vehicle battery will cancel the fault memories
of control
units. Consequently, before disconnecting the car's battery, always
interrogate the fault memories. Investigate stored faults and, once any
faults have been remedied, cancel the fault memory.
- Control unit plugs should only ever be connected and disconnected
while
the ignition is turned off.
- The removal and installation of components, relays, fuses etc. can
cause
faults to be stored in fault memories capable of self diagnosis. Always
interrogate the fault memories after completing work on the electrical
system.
- Investigate stored faults and, once any faults have been remedied,
cancel
the fault memory.
Comply with the following when replacing the DME/DDE (Digital Motor
Electronics/Digital Diesel
Electronics):
- Always read out hardware/software version of the corresponding control
unit with DIS tester.
Comply with the instructions of the DIS tester on the steps coding and
programming.
On vehicles with electronic vehicle immobilization, comply with the
instructions of the DIS tester.
- Each control unit is programmed with certain basic values, which serve
as mean values. The control unit
receives different input values, depending on engine condition, which are
compared with the stored
values. The adaptive system compares the input values with the stored map
values. The control
commands are routed to the relevant actuators.
- If, for example, the DME control unit would be without current for a
long time (more than an hour), its
adaptive system would lose the stored values. When a cleared control unit is
restarted or a new control
unit is installed, the adaptive system must read in and store the input
values of the associated engine as
new basic values itself.
- This procedure could lead to erratic idling and disturbed overrunning of
the engine after starting.
Depending on the engine it could require some time before all values are
adapted to the engine condition.
- Therefore observe the following procedure before replacing or
reinstalling a DME/DDE control unit:
- If possible before exchanging control unit, run engine up to
operating temperature.
- Remove the control unit, install a new control unit and operate
vehicle at different engine speeds.
NOTES ON CHECKING IGNITION SYSTEM
-> Spark plug faults
-> Ignition coil faults
-> Further fault patterns with evaluation
-> Additional fault notes for troubleshooting
Oscillograms -> Normal oscillogram
-> Oscillograms of ignition coils from different manufacturers
Check -> Secondary signal for stationary ignition distribution
READ NEXT:
REPLACING ALL SPARK PLUGS (N42, N40, N46, N45, N52, N52K, N51)
Special tools required:
12 1 171
12 1 200
Necessary preliminary tasks:
Switch off ignition
Remove ignition coils.
Unscrew spark p
NOTES ON CHECKING IGNITION SYSTEM
Troubleshooting -> Fault in fuel injection system
-> Spark plug faults
-> Ignition coil faults
-> Further fault patterns with evaluation
-> Additional
SEE MORE:
Principle
The system reads if the front passenger seat is
occupied by measuring the human body's resistance.
Front, knee, and side airbag on the front passenger's
side are activated or deactivated.
General information
Before transporting a child on the front passenger
seat, refer to the safety info
Necessary preliminary tasks:
Remove heater
Release screws (1).
Fig. 84: Identifying Screws
Release screws (1) and remove expansion valve (2).
Installation:
Ensure that seals are correctly seated.
Replace sealing rings and moisten with refrigerant oil.
Tightening torque.
Fig. 85: Identifying E