Instrument Cluster Display Functions
All the gauges on the cluster are electronically driven analog needle displays. The inputs to the cluster are processed by the main circuit board as follows:
Road Speed - The signal from the rear axle reed contact is processed by the cluster for display. The processed signal is also transmitted as an output of the cluster as "Speed Signal A" to other control modules that require road speed as an input.
Fuel Gauge - Two lever type floats wired in series provide the input for the fuel gauge display.
When the fuel reserve threshold is reached, the low fuel warning LED is illuminated.
Engine Speed - The "TD" signal is a processed output of the engine control module that the cluster uses for the tachometer display. This signal is provided by the CAN bus from 1999 for the Z3.
Economy Display - The cluster uses the "Ti" and road speed input signals to determine the instantaneous fuel consumption for display on the gauge.
This gauge is not equipped on 318ti and roadster instrument clusters.
Coolant Temperature Gauge - The input signal from the engine coolant temperature sensor is processed for display on the temp gauge.
The overheat warning LED is illuminated if the coolant temperature exceeds approximately 125° C (240° F).
Total Mileage/Trip Odometer - The signal from the rear axle reed contact is also processed for accumulated mileage display.
The processed signal is displayed in the LCD block below the speedometer. Depending on model and year, the total mileage reading is stored electronically as follows:
- 1992-1996 E36 4 door/coupe/convertible/M3 in an EEPROM on the main circuit board.
- 1995-1999 318ti in an EEPROM on the main circuit board and in the instrument cluster coding plug.
- 1996-2002 Z3 in an EEPROM on the main circuit board and in the instrument cluster coding plug
- 1997-1998 E36 4 door/coupe/convertible/M3 in an EEPROM on the main circuit board and in the instrument cluster coding plug.
Service Interval Indicator - SI information is also displayed in the LCD block with the mileage - when the ignition is switched on. All models use SI II processing for "Oil Service "and "Inspection" intervals.
Indicator and Warning Lamps - The various lamps are positioned at the top center and along the bottom of the cluster display. They are controlled internally by the cluster or externally by other sensors and modules where required by legislation.