BMW X5 Owners & Service Manuals

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:

General notes on disconnecting battery:

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:

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:

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:

Comply with the following when replacing the DME/DDE (Digital Motor Electronics/Digital Diesel Electronics):

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:

 Ignition Wires, Spark

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

 Ignition Coil

NOTES ON CHECKING IGNITION SYSTEM Troubleshooting -> Fault in fuel injection system -> Spark plug faults -> Ignition coil faults -> Further fault patterns with evaluation -> Additional

 Electronic Switching On Or Control Unit

SEE MORE:

 Start/Stop button

Principle Pressing the Start/Stop button switches drive-ready state on or off. Drive readiness is switched on when you depress the brake pedal while pressing the Start/Stop button. Pressing the Start/Stop button again switches the drive-ready state back off and standby state is switched back on. A

 Manually Unlocking Transmission Lock

For various tasks, it is necessary to unlock and lock the transmission lock. This can be done from inside or underneath the vehicle. From vehicle interior: Refer to MANUAL EMERGENCY UNLOCKING OF TRANSMISSION LOCK. Underneath car: Remove underbody protection. Press lever (1) towards rear.

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