Speedometer with odometer and tripmeter.
| Speedometer with odometer and tripmeter. |
The main instrument unit is fitted with an electronic speedometer. The ABS control module receives speed information from the left rear wheel sensor. The information is processed and sent continuously to the main instrument connection pin 3.
The information in the form of a square wave pulse varies periodically between B+ and 0 V. This takes place 29 times per wheel revolution.
With the wheels stationary, the voltage may be either B+ or 0 V.
The main instrument unit uses the frequency to calculate the vehicle speed.
The speedometer is controlled by a stepper motor which is pulse-controlled by the main instrument control module. The main instrument unit also emits information on the speed to the bus.
| Odometer/tripmeter |
The main instrument unit's control module stores the distance driven and shows it on the odometer display. The display has a six-digit register which the control module updates continuously from 000000 to 999999 km (or miles). The tripmeter has a four-digit register which starts at 000.0 and runs to 999.9 km (or miles). When the ignition is ON, the tripmeter can be zeroed with the reset button. If the reset button is pressed while the ignition is OFF, the display lights up for 20 seconds and the odometer mileage can be read.
Information on the distance driven is sent out on the bus by the main instrument unit. This information is used by the SID unit, for example.
Diagnostics
If the vehicle speed information exceeds 270 km/h, diagnostic trouble code B1705 is set.The function has its own diagnostics in the sending system.
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