An Overview

62 01 04 (074)
Instrument cluster
E81, E87, E90, E91, E92, E93





Introduction
On the BMW 1-Series, the instrument cluster has an analogue display for:

- Speed
- Speed
- Fuel level
On the BMW 3-Series, the instrument cluster has an analogue display for:
- Speed
- Speed
- Fuel level
- Fuel-consumption indicator
- Cruise control with moving-disc instrument for:
- Cruise control with brake function (option 544)
- Active cruise control (option 541)
The scales on the instrument cluster depend on the country concerned and the engine installed. All indicator and warning lights that are stipulated by law are located between the two large pointer instruments.
Under the two large pointer instruments there is an LCD display (e.g. for Check-Control message symbols).
New for the instrument cluster, gradual introduction from 03/2007 (depending on engine version):
- Shift point indicator
- Additional Check-Control messages for automatic engine start/stop system

On vehicles with multi-audio system controller (M-ASK) or Car Communication Computer (CCC):
Various displays appear in parallel on the Central Information Display (CID), e.g. information concerning CBS or Check Control.

Brief description of components
The following components deliver signals to the instrument cluster:

- Outside temperature sensor
The outside temperature sensor is connected to the junction box electronics (JBE).
Wires lead from the JBE to the instrument cluster.
The outside temperature is displayed on the LCD display in the instrument cluster.
When terminal 15 is OFF, the outside temperature sensor will continue to measure the temperature for a maximum of 24 hours.
The signal from the outside temperature sensor is digitised in the instrument cluster. A computation model compensates for the effect of the residual heat from the engine compartment on the signal.
A lower damping value is set at higher speeds or low engine temperatures. The true outside temperature can only be reliably expected from a roadspeed of about 80 km/h.

- SZL: Steering Column Switch
Two switches are located on the turn-signal/main-beam switch on the steering column switch cluster (SZL): an axial switch and a rocker switch.
The following contents can be called up with the two switches and shown on the LCD display in the instrument cluster:
- On-board computer functions and Check-Control confirmation
- Menu for the following functions (display is encoding-dependent, also in CCC or M-ASK, depending on equipment fitted):
- Dim instrument illumination
- Scroll Check-Control message
- Check engine oil level
- Run Flat Indicator initialisation
- Set time
- Set date
- CBS settings
- Personal Profile settings

- FRM: Footwell module
The footwell module (FRM) controls the interior and exterior lighting.
From the footwell module, information is sent through the K-CAN, e.g. whether or not the indicator and warning lights stipulated by law need to be actuated.
- JBE: Junction box electronics or junction box
The junction box electronics send the following signals to the instrument cluster:
- Coolant level (Check-Control message)
- Washer fluid level (Check-Control message)
- Fuel level via 2 fuel level sensors (used by instrument cluster to compute the Check-Control message)
- Parking brake applied (general brake warning lamp)
The junction box is also the gateway between the PT-CAN and the K-CAN. The PT-CAN is used, e.g. for DME/DDE and DSC messages.
The K-CAN is used, e.g. for terminal control signals from the CAS control unit.
The instrument cluster receives its power supply from the junction box terminals 30 and 31.
- MRS: Multiple restraint system
The multiple restraint system (MRS) is a bus participant on the K-CAN.
The MRS control unit sends the message whether the airbag warning light or seat belt indicator light needs to be actuated.
- DME or DDE: Digital engine electronics or digital diesel electronics
The DME/DDE supplies the following signals (for example) to the instrument cluster: Engine speed and injection rate.
The message is sent through the PT-CAN and then through the K-CAN. The DME/DDE also indicates whether an exhaust-related fault has developed (actuation of emissions warning light).
> On vehicles from 03/2007
Depending on the engine version installed, an automatic engine start/stop system may be fitted. The engine management controls this function.
If a fault develops in the automatic engine start/stop system, the engine management will generate a corresponding Check-Control message. The instrument cluster displays the Check-Control message.
- DSC: Dynamic Stability Control
The brake pad wear sensors are connected to the DSC control unit. The DSC also sends further messages to actuate indicator and warning lights in the instrument cluster:
- ABS indicator and warning light.
- DSC indicator and warning light.
- DTC indicator light.
- General brake warning light
- EGS: Electronic transmission control
On vehicles with automatic transmission:
A signal from the EGS control unit causes the gear program display or gear indicator in manual mode to be shown in the LCD display.
On vehicles with manual transmission:
No gear indicator. The area is used (via encoding) for a larger on-board computer function display.
- Cruise control with brake function or active cruise control
On vehicles with 6-cylinder engine and longitudinal dynamic management (LDM control unit):
The set speed is transmitted by the LDM control unit to the instrument cluster on the PT-CAN and K-CAN.
During active cruise control, an additional indicator light is activated as a distinguishing feature for cruise control with brake function. The distance to the vehicle in front is indicated with 3 bars. The set speed for active cruise control appears briefly in the LCD display (in addition to permanent display with the moving-disc instrument).
> BMW 3-Series:
On vehicles from 06/2006, cruise control with brake function is integrated into DSC.
These vehicles then only have an LDM control unit if active cruise control is fitted.
- Body CAN
The instrument cluster receives all other messages that could mean a display in the instrument cluster (e.g. Check-Control messages) through the body CAN (K-CAN).
System functions
The instrument cluster comprises the following system functions:

- Operational readiness
- Operating voltage range
- Brightness control
- Actuation for moving-disc instrument
- Shift point indicator
- Redundant data storage



Operational readiness
Operational readiness depend on the terminal.
- Terminal 30
The instrument cluster is connected to terminal 30 via the junction box.
The terminal status (terminal R or terminal 15) is sent to the instrument cluster via the K-CAN. If terminal 30 is active (terminal R OFF), the instrument cluster is in standby mode.
The instrument cluster can be activated by pressing the reset button - the following are then displayed: distance recorder, clock, outside temperature, fuel level (can be encoded).
The display goes out after 25 seconds.
- Terminal R
The following are evaluated when terminal R is switched ON: turn-signal/main-beam switch and fuel level sensor.
The time and outside temperature appear in the LCD display.
The on-board computer functions can be called up via the on-board computer button (display unlimited).
- Terminal 15
When terminal 15 is switched ON, a pre-drive-check is carried out on the permanent indicator and warning lights. The display elements show the current figures, e.g. fuel level.
- Terminal 50 (starter motor)
While the engine is being started, the on-board supply voltage may drop so far that the internal voltage supply (6 volts) can no longer be maintained.
In this case, no analogue signals can be evaluated. Moreover, no data will be able to be stored (in EEPROM).



Operating voltage range
The operating voltage range is from 9 to 16 volts. If the voltage drops below 7.5 volts, undervoltage will be recognised. If the voltage rises over 16 volts, no analogue inputs can be evaluated.



Brightness control
The instrument cluster is illuminated when the lights are switched ON.
A phototransistor is installed in the instrument cluster to calculate the necessary brightness (display, indicator and warning lights, scales, needles).
The brightness value calculated in the instrument cluster is output on the K-CAN (e.g. for the Central Information Display).
Dimming can be set individually via a menu in the instrument cluster.
When the vehicle lighting is switched on, these individual settings and the phototransistor are used to control the dimming.
When the vehicle lighting is switched off, the dimming is only controlled by the phototransistor (display brightness according to ambient light).



Actuation for moving-disc instrument
The moving-disc instrument for the set speed is driven by a stepper motor.
The signal for the set speed is transmitted on the bus by the control unit for longitudinal dynamic management (LDM). This signal is converted to control pulses for the stepper motor.
The set speed is transmitted with a "resolution" of 1 km/h and displayed.



Shift point indicator
The shift point indicator is only available in conjunction with manual transmission.
A great deal of fuel can be saved by changing gear in good time. The shift point indicator assists the drive in this. The current driving situation is identified on the basis of roadspeed and vehicle acceleration. If the gear currently engaged is not the most economical, a gear change recommendation appears in the display. The shift point indicator can be activated and deactivated on the on-board computer. The shift point indicator is deactivated when the vehicle is delivered.



Redundant data storage



The following instrument cluster data are redundantly stored in the Car Access System (CAS):
- Distance recorder
- Trip meter
- CBS data
This is conditional upon the same vehicle identification number being stored in both control units.
If different vehicle identification numbers are stored, the manipulation dot will appear in the LCD display.

Important: Do not replace the instrument cluster and the CAS control unit at the same time.
The instrument cluster and the CAS must not be replaced at the same time. CBS data would then be lost.

Notes for service staff
The following information is available for service staff:

- General note:
- Diagnosis:
- Encoding/programming: ---
Subject to change.