OVERVIEW
The light check module LCM has been redesigned for Model Year 99 as of 9/98 production. It is now identified as the LCM III and is installed in both the E38 and E39 vehicles.
Identifying Light Check Module III (LCM III). Scheme 53
The module itself has been redesigned with new semi-conductor final stages that produce less heat in operation. This has allowed for the elimination of the protruding heat sink found on the previous LCM.
The total scope of function and features has been expanded to improve the comfort and safety for the driver and passengers of the vehicle. Feature and functional changes to the LCM include
- Replacement lighting for the parking lights
- Limiting of output voltage to the lamps
- Follow Me Home (delayed exit) lighting
The automotive industry/press often identify xenon lighting systems as HID (high intensity discharge) systems. Xenon headlight technology was first introduced to the US market exclusively on the E32 750iL in 1993. BMW xenon headlight systems have evolved and their availability as optional equipment has spread throughout the model lineup.
Blue/White in color and using ellipsoidal technology Xenon headlights provide improved night time visibility in all driving conditions compared with traditional Halogen bulb headlights.
VERSION IDENTIFICATION & SYSTEM SUMMARIES
Version identification is specific to vehicle model with the exception of the E38.
There are two E38 Xenon systems. The early system identified as Generation 2.1 and equipped on 95-98 model year 750iL vehicles. The headlight design of this version has a flat bottom edge.
The Generation 3 system has been introduced on 1999 model year E38 vehicles. This system can be visually identified by the rounded bottom edge as of the headlight assembly shown.
Identifying E38 Generation 3 Headlight. Scheme 54
LWR: All 1999 model year systems are also equipped with LWR (Headlight Beam Throw Control). This system automatically adjusts the vertical position of the headlight beams to compensate for vehicle loads ensuring optimum beam throw. LWR components and function is described further on in this section.
Headlight Replacement Parts: In previous model years, individual replacement parts were not available for headlight assemblies. This was due to the Federal Motor Vehicle Safety Standards (FMVSS) relating to pitting or corrosion of the reflector components in non-sealed beam light assemblies.
BMW has recently submitted corrosion test data for headlight replacement components which have passed the FMVSS providing availability of headlight assembly spare parts. The approval has been given for all Bosch headlight assemblies (including halogen systems). Hella system components are currently being tested and in all likelihood be available in the near future.
| Vehicle/ Model | Model Year | Manufacturer(s)/Version ID | LWR- Head Throw Cont. | Individual Replacement Parts Available |
|---|---|---|---|---|
| E32/750iL | 93-94 | Hella (Light & CM "control module") Generation 1 | No | No |
| E38/750iL | 95-98 | Bosch (Light & CM) Generation 2.1 | No | Yes |
| E38/All | 99 | Bosch (light) Hella (CM) Generation 3 | Yes | Yes |
| E39 All | 99 | Hella Generation 3 | Yes | No (possible in future) |
| E46 | 99 | Bosch (Light & CM) | Yes | Yes |
HEAD LIGHT SPECIFICATION CHART
Phases of Bulb Operation
Starting Phase: The bulb requires an initial high voltage starting pulse of 18-25kV to establish the arc.
Warm Up Phase: Once the arc is established the power supply to the bulb is regulated to 2.6A generating a lamp output of 75 watts. This is the period of operation where the xenon gas begins to brightly illuminate. The warm up phase stabilizes the environment in the bulb ensuring continual current flow across the electrodes.
Continuous Phase: Once the warm up phase is completed, the system switches to a continuous mode of operation. The supply voltage for the bulb is reduced and the operating power required for continual bulb illumination is reduced to 35 watts which is less than a conventional halogen bulb.
Functional Description
To regulate the power supply to the bulbs, additional components are required. The xenon control modules (1 per light) receive operating power from the lighting control module (LCM E38/E39 - LSZ E46) when the headlights are switched on. The xenon control modules provide the regulated power supply to illuminate the bulbs through their phases of operation.
The igniters establish the electric arcs. Integral coils generate the initial high voltage starting pulses from the control module provided starting voltage. Thereafter they provide a closed circuit for the regulated power output from the control modules.
Xenon Light Power Flow Circuit Diagram. Scheme 55
LWR automatically adjusts the vertical positioning of the headlights to maintain optimum headlight beam positioning for maximum driving visibility and to prevent undue glare for oncoming motorists. The system compensates for vehicle load angle changes (ie: diminishing reserve of gasoline in fuel tank during a long journey, overloaded cargo weight, etc.)
LWR has been available on BMW vehicles in other markets for quite some time. Starting with the 1999 model year all US market vehicles with Xenon Lights incorporate LWR as standard equipment. LWR is not available with standard halogen headlights.
LWR monitors the vehicle's loaded angle via two hall effect sensors mounted to the front and rear suspension members. When an adjustment is necessary, LWR simultaneously activates two stepper motors (one in each headlight assembly).
The stepper motors drive a threaded rod that moves the lower edge of the headlight carrier plate forward and backward (depending on driven direction). The upper edge of the headlight carrier plate is fixed on a pivot. The pivoting movement adjusts the vertical position of the headlight beam.
Identifying Normally Loaded Vehicle. Scheme 56
Identifying Overloaded Vehicle (Exaggerated). Scheme 57
The E46 LWR system comes on-line when the ignition switch is turned to KL 15. The E38/E39 system comes on-line when the lights are switched on.
The LWR control electronics then cycles the stepper motors through their full range of motion and stops at a default position.
The control electronics monitors the level sensor input signals to determine the vehicles load angle and adjusts the beam position accordingly. As the vehicle is driven it continually monitors the level sensor signals and if necessary updates the headlight beam positions every 25 seconds on the E46 or momentarily on the E38/E39 system.
Abrupt fluctuations of the sensor signals are filtered to prevent unnecessary adjustment as well as monitoring road speed and brake pedal application as correction factors.
Components/Operation
Interior door handle illumination is provided by orange glow light strips illuminated by LED's.
Scheme 58
- The light strips are part of the door handle shell and are not replaceable.
- The LED's are individually replaceable (P/N 63 31 8 381 051). (Scheme 58): Identifying Interior Door Handle Lighting Components
The LED's are connected to the KL 58g interior panel lighting circuit. KL 58g is an output pulse width modulated control signal from the LCM III. The duty cycle changes when the LCM III detects a change in the voltage drop at the light dimmer input signal.
Interior Door Handle Lighting is on whenever the vehicles lights are switched on.
