Speedometer With Odometer and Trip Meter

Speedometer with odometer and trip meter

Speedometer












The main instrument unit is fitted with an electronic speedometer. The ABS control module receives information on vehicle speed from the rear left-hand wheel speed sensor. This information is processed and conveyed continuously to terminal 10 (K12) of the main instrument unit's control module.

The information, in the form of a square wave pulse, varies periodically between B+ and 0V.

The main instrument supplies the current and the ABS control module grounds the output.
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 powered and controlled by the main instrument unit control module, which converts the frequency modulated signal to km/h or mph. A correction is made depending on the programmed tyre size, whereby the speed information is put on the bus.

Odometer/trip meter
The main instrument unit control module stores the distance driven and shows it on the odometer display. The display contains a six-digit counter which the control module continuously updates from 000000 to 999999 km (or miles). The trip meter has a four-digit counter which starts at 000.0 and runs to 999.9 km (or miles). With the ignition ON, the trip meter is zeroed with the reset button. The display will be activated for 20 seconds if the reset button is pressed with the ignition OFF. An odometer reading is then obtained.

Information on the driven distance is put on the bus by the main instrument unit. The information is used by SID, among others.

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.

Speedometer, odometer and trip meter (TC/ABS)

Speedometer












The main instrument unit has an electronic speedometer. The TC/ABS control module receives vehicle speed data from all wheel sensors. The information is processed and transmitted continuously on the P bus. The main instrument unit reads the speed information from the rear left wheel and converts this to km/h.

The information to the TC/ABS from the wheel sensors is in the form of a square wave that varies between B+ and 0 V 29 times per wheel revolution.

With the wheels stationary, the voltage may be either B+ or 0 V.

The speedometer is supplied with current and is controlled by the main instrument unit control module, which also sends information on the speed to the bus.

Odometer/trip meter
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 trip meter has a four-digit register which starts at 000.0 and runs to 999.9 km (or miles). When the ignition is ON, the trip meter 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 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, 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.