Instrument Cluster (E46)
Instrument Cluster (E46)
General
The instrument cluster features three bus interfaces which enable the information link (data link/serial) to the connected control units.
These busses are:
- K-bus (body bus)
- CAN-bus
- Diagnosis bus
Coded data which determine the scope of functions of the instrument cluster are stored in a non-volatile data memory (data are retained when supply voltage is disconnected).
Replacing Instrument Cluster
The four cases described in the following show the steps which must be taken under certain circumstances in order to ensure trouble-free replacement of the instrument cluster.
Case 1: The instrument cluster control unit is defective and the light switching center (LSZ) is OK.
Case 2: The instrument cluster control unit is OK and the light switching center (LSZ) is defective.
Case 3: The control unit for the instrument cluster and the control unit for the light switching center (LSZ) must be replaced.
Only replace both control units at the same time when this is unavoidable (stored total odometer reading is irretrievably lost).
NOTE: Disconnect battery.
Case 4: As a check, replace the control unit for the instrument cluster or the light switching center control unit (LSZ).
NOTE: Although exchanging one of the two control units is possible in principle, it should, however, be avoided wherever possible.
Scope of function
Following functions are displayed or used for a function:
Test functions
System test (Test No. 2): This system test facilitates simple visual assessment of the instrument cluster (pointer instruments, displays, lighting, warning lamps and indicator lamps).
Selecting system test function
The system test is started by pressing the left-hand button in the instrument cluster (trip recorder reset button. The button must be pressed and held with the ignition lock in "0" position, now turn the ignition lock to position "1" (terminal R radio setting) and release the button. When "test 1." appears in the display press the button once again, "test 2." now appears. After a short period of time, the display changes to "test 2.0". The system test can now be started by pressing the button once again.
By switching the terminals, ignition lock from position "1" (terminal R radio setting) to position "2", the two-colored indicator lamps are activated yellow and red. On completion of the system test, it can be repeated by pressing the button once more.
These elements are:
- All pointer instruments (pointers are moved once over their indication range)
- All LC displays with a segment test and their background lighting
Indicator and warning lamps for:
- High beam
- Oil pressure (red) (ignition lock in position 2/terminal 15) or
- Oil level (yellow (ignition lock in position 1/terminal R)
- ASC
- Front/rear fog lights
- Windshield washer fluid level
- "CHECK ENGINE"
- EML (EPC) / MDK
- Coolant level
- Brake pad wear
- Tire pressure control
- Cruise control
- Belt warning
- Fuel reserve
- Coolant high temperature
- Left/right direction indicators
- Windshield washer fluid level
- Shift indicator (if automatic transmission is coded)
- Cruise control (Tempomat) cut-in
- Battery charge indicator lamp
- General brake warning lamp (at terminal 15)
All test functions, apart from test numbers one and two, are interlocked and must be released by means of test function number nineteen.
Selecting test functions
The test functions are started by pressing the left-hand button in the instrument cluster (trip recorder reset button. The button must be pressed and held with the ignition lock in "0" position, now turn the ignition lock to position "1" (terminal R radio setting) and release the button. Once " test 1. " appears in the display the required test can be selected by pressing the button. " test 2. " " test 3. " " test 4. " etc.. now appear in the display. After a short time, the display changes to " test x.0 " (x stands for selected test group), by pressing the button once again, it is possible to switch to another test in the test group or, as in the system test, start the respective test.
If the test is a locked test (test 3 to 21) the lock is released with test 19 by pressing the trip recorder button when "_L_oFF" appears in the display. The display then jumps to test 0 so that the corresponding test group can be selected by briefly pressing the button.
Test No. 1 - 7:
Test No. 8 - 21:
