BMW ALTERNATOR Problems and Faults

Idler Pulley for Drive Belt
Model:
BMW E36 – BMW 328iA with M52 Engine
Complaint:
Due to the drive belt idler pulley not being installed correctly during production it may cause under certain conditions a belt noise and premature wear on the main pulley belt which guides the water pump, generator and power steering pump.
Remedy:
Install the drive belt idler pulley on all affected vehicles by:

-Removing the drive belt tensioner pulley cap.
-Relieve the tension on the drive belt and remove it from the generator pulley. (If the mileage on the vehicle is greater than 60 miles, the drive belt must be replaced.)
-Remove the upper generator mounting bolt.
-Install the new upper generator mounting bolt with idler pulley. (The tab on the back of the pulley hub must be in line with the notch in the generator bracket.
-Reinstall the drive belt.
-Reinstall the drive belt tensioner pulley cap and the new idler pulley cap.

Replacement of Water-cooled Generator on BMW E38 M73TU Vehicles
Model:
BMW E38 750iL 750iLP produced September 1998 – May 2000
Complaint:
As a result of frequent short journeys with a large number of electrical consumers switched on, an adequate charge level may not be maintained by the vehicle’s electrical system battery which can as a consequence result in a no-start situation.
Remedy:
A modified water-cooled generator with a new ribbed V-belt can be installed. This is able to cope with short journeys due to its higher generator voltage and higher current capacity at slower speeds. The following services should be carried out on all effected vehicles.

-SI 61 09 00 – Replacement of the Battery Isolation Switch on E38 M73TU vehicles.
-SI 61 10 00 – Replacement of the Vehicle Electrical System Battery on E38 M73TU vehicles.
-SI 12 09 00 – Increase of Idle Speed on E38 M73TU vehicles.

Reprogramming the DME/ECM – E38 m73TU Vehicles
Model:
BMW E38 750iL, 750iLP produced August 1998 – February 2000
Complaint:
As a result of frequent short journeys with a large number of electrical consumers switched on, an adequate charge level may not be maintained by the vehicle’s electrical system battery which can as a consequence result in a no-start situation.
Remedy:
The battery voltage needs to be at the correct specification, once this happens the engine speed will return to base idle. In order to do this using CD V22.0 or higher, reprogramme the ECM/DME of the effected vehicles, this will temporarily increase the engine idle speed but only if the battery voltage is below specification. The following services should be carried out on all effected vehicles:

-SIB # 12 08 00 – Replacement of Alternator on E38/M73TU
-SIB # 61 09 00 – Replacement of Battery Isolation Switch E38 M73TU
-SIB # 61 10 00 – Replacement of Vehicle Battery on E38 M73TU
-SIB # 84 06 00 – Retrofitting Adaptor Cable for MK II Plus

Navigator Computer on E38, E39, E46 Vehicles

Alternator Mounting Bolt
Model:
BMW 325e, BMW 528e produced on December 1985, January 1986, and February 1986
Complaint:
The alternator pivot belt used with the solid mounting produced in the above vehicles may have a bolt head that could contact the alternator belt.
Remedy:
Visually check the cars with above production dates to see if they have solid mounting. The pivot bolt should have a thickness of 4mm, if the pivot bolt exceeds 4mm then replace with P/N 12 31 1716 014 and spring washer P/N 07 11 9 932 095.

Use of Constant Current Generator
Model:
BMW 318i, BMW 325e, BMW 528e which are equipped with an adjustable, all-metal control valve.
Conditions:
The above vehicles with the adjustable, all-metal idle control valve cannot be adjusted to the specifications outlined in S.I’s 13 09 86 (1179) and 13 10 86 (1184).
Remedy:
If this condition is experienced however, the engine meets all the requirements for idle and idle control valve current outline in S.I’s 13 09 86 (1179) and 13 10 86 ( 1184) then use the Constant Current Generator as a diagnostic tool to establish whether the Idle Control Valve or Idle Control Unit is faulty. Use the following procedure, however, do not use the constant current generator for the final adjustment of the idle valve.

-Disconnect the plug on the idle control valve.
-Connect the current generator plug to the idle control valve.
-Connect the current generator leads to the car battery.
-Set the current generator switch to 160Hz (318i), or 140Hz (325e, 528e).
-Run the engine at idle speed.
-Turn the adjustment screw on the side of the idle control valve clockwise so it is completely closed.
-Slowly open the adjustment screw by turning counter clockwise until the nominal RPM range is reached:

750 plus/minus 50 RPM = 318iA
850 plus/minus 50 RPM = 318i
700 plus/minus 50 RPM = 325e/528e

-If this RPM can be reached then change the idle control unit.
-If this RPM cannot be reached then change the idle control valve.
-Stop the engine.
-Disconnect current generator leads from the battery and plug from idle control valve.
-Replace the defective part.
-Readjust engine RPM,CO and idle control valve current with the digital multimeter and procedures which are outlined in the 1986 Gasoline Engine Campaign Bulletins, i.e 13 09 86 (1179) and 13 10 86 (1184).
-Do not use the current generator for the final adjustment of the engine RPM, CO, and/or Idle control valve current. Only the multimeter will give an exact adjustment.

Headlight Brightness and Idle speed Fluctuations
Model:
BMW E46 3 Series produced September 1999 and August 2001
Complaint:
To have both seat heating elements turned on may cause headlight brightness and idle speed fluctuations, which is caused by the voltage drops induced by the load response function of the alternator.
Remedy:
Replace the Centre Console Switch Module with P/N 61 31 6 914 744.

Premature Battery Discharge
Model:
BMW E31 850 CSi with EWS 11 produced from January 1995 up to September 1995.
Complaint:
When the vehicle has been parked for a few days, the vehicle may not start, due to the vehicles battery not maintaining an adequate charge level. The vehicle owner may also experience a humming noise from the EML actuator motors after the engine is switched off.
Remedy:
Install the Isolation Relay Kit (PN 99 00 0 002 354) between the circuit of DME1 and its main relay, and the circuit of DME2 and its main relay.

Replacement of Battery Isolation Switch
Model:
BMW E38 750iL, 750iLP produced in September 1998 to October 1999.
Complaint:
As a result of frequent short journeys with a large number of electrical consumers switched on, an adequate charge level may not be maintained by the vehicle’s electrical system battery which can as a consequence result in the vehicle not starting.
Remedy:
Check the wiring at the X1806 and the part number of the battery isolation switch, if required install a retrofit wiring harness and/or replace the battery isolation switch. If the retrofit harness is installed, then the ignition starter switch also needs to be replaced.
The following Service Actions should also be carried out on all affected vehicles:

-SI 61 10 00 – Replacement of Vehicle Electrical System Battery on E38 M73TU Vehicles.
-SI 12 08 00 – Replacement of Water-cooled Generator on E38 73TU Vehicles.
-SI 12 09 00 – Increase of Idle Speed on E38 M73TU Vehicles.

Replacement of Vehicle’s System Battery and Battery Holder on E38 M73TU Vehicles
Model:
BMW E38 750iL, 750iLP produced from September 1998 – April 2000
Complaint:
As a result of frequent short journeys with a large number of electrical consumers switched on, an adequate charge level may not be maintained by the vehicle’s electrical system battery which can as a consequence result in the vehicle not starting.
Remedy:
To find if a vehicle is affected by this Service Action then the Service Menu of the Dealer Communication Programme must be employed. If necessary after the results of the system continue with the corrective action or take no action at all.
If the vehicle has been affected then install a larger capacity (70 Ah) system battery and a new battery holder. The following services must also be carried out:

-SI 61 09 00 – Replacement of Isolation Switch on E38 M73TU Vehicles.
-SI 12 08 00 – Replacement of Water-cooled Generator on E38 M73TU Vehicles.
-SI 12 09 00 – Increase of Idle Speed on E38 M73TU Vehicles.