Fault indicators, the display of which is located in the middle of the instrument cluster, are divided into groups «danger signal» And «warning signal».
Malfunctions that significantly affect traffic safety or that result in serious damage are considered dangerous, and therefore the signals light up in red. These are the following signals:
Brake system: brake fluid level too low.
Engine oil pressure: oil pressure drops below 0.3 bar at idle, or 1.8 bar is not reached at speeds above 2100 rpm (models with 4- and 5-cylinder engines and with 6-cylinder engines from 7/91) or 2.5 bar (models with 6-cylinder engines since 8/91).
Coolant: The coolant temperature rises above 120°C, or the operating temperature is not reached, or the coolant level is too low. In addition to the danger light signal, a three-time buzzer comes from the instrument cluster. Hazard alarms have priority over warning alarms in the system. As long as the danger signal exists, the warning signal is suppressed. It appears only after the cause of the danger signal has been eliminated.
Warning signals are displayed on the panel in yellow and are accompanied by a single buzzer. These are the following signals:
Stop lamp: this symbol appears immediately after the ignition is switched on. If you press the brake pedal, the symbol disappears, provided that both brake lights are working.
Lighting: This test step cannot be performed fully automatically by the self-test system. First, the driver must turn on the dipped beam. At the same time, dipped beam and rear dimensions are controlled. Simultaneous failure of both dipped-beam filaments or taillights is not shown by the system. But in general, this malfunction is unlikely to occur.
Battery: The battery symbol flashes when the battery voltage is outside the 10.6-15.6V specification.
Washer system: This indicator indicates that the level of washer fluid in the reservoir is too low.
Fuel tank: The refueling symbol comes on when there is only 12 liters of petrol left in the fuel tank. If there are several malfunctions on the warning signal board, the warning signals flash in turn when the ignition is turned on.
Signal «OK» should appear if, after turning on the ignition and pressing the brake pedal, the inscription goes out «Bremslicht» (stop signal). «OK» in this case means that all test steps were completed without error messages. After a short time, the signal goes out.
After removing the tachometer (2) printed circuit board and indicator board of the auto-test and self-diagnosis system (1) unscrew from the main.
The control station for car lighting functions quite differently. These devices work on the electromagnetic principle and compare the current flowing in the wiring, for example, to the left and right dipped beam. If there is no current flow in any wire due to a break or defect in the lamp, the control device detects the difference and reports this to the control unit. In the event of a failure of both lamps, which occurs very rarely, of course, no difference is noted either. In this case, the control device is unable to determine the fault.
Hint: when connecting the trailer connector, make sure that the wires are connected to the rear markers before connecting to the lamp health indicator (it is located at the rear left in the luggage compartment). If the power is taken from one of the rear dimensions, then with the trailer lighting connected, unaccounted information about the currents in the circuit arrives in the lamp health device, and it reports about «lamp defect».
Removing the Control Module
The control unit for the self-test system is screwed to the back of the instrument cluster in the same housing as the indicator unit. You will find a description of the removal of the autocheck system module at the beginning of this chapter in the section «Disassembly».
Troubleshooting the self-diagnosis system
Control of the self-diagnosis system at home is only partially possible: first, all sensors should be checked - if a malfunction was not found here, then it should be looked for in the self-diagnosis system module.
The sensors are checked in the same way as when checking the indicators of a conventional dashboard, see previous pages.
The water level sensor in the cooling system, which is installed only in the autotest system, is checked as follows: if the indicator is on, despite the full tanks of the cooling system, disconnect the cable plugs at the tank. If the warning signal now goes out, the sensor is faulty.
Checking devices to determine the malfunctions of the front and rear lamps (installation location: relay box on the left rear in the engine compartment) you must provide the workshop.
Independent control of the block of indicators
Press with the ignition on and standing (or moving at a maximum speed of 5 km/h) car button at the bottom left of the instrument cluster.
If the indicators and the system are in good order, all signal-symbols should appear in turn on the instrument panel.
This check is not possible if the danger signal is on.
Additional functions on the display of the self-diagnosis system
Speed Warning: After recording the speed of movement at a given time, the self-diagnosis system indicates a significant excess of this speed by the appearance of a symbol and a buzzer. This entry is retained until the ignition is turned off, unless a different driving speed has been recorded or the memory has been erased (keep the leftmost button pressed for a second).
Radio frequency indicator: if the indicator field is not occupied by information from the self-test system, then data on the frequency of radio stations on appropriately equipped car radios appear on it. If the radios are also transmitting Radio Data System signals, the indicator field will display «RDS». The name of the radio station can then be read on the radio display.
Removing switches.
Left: Loosen two Phillips screws (arrows) with the relay removed. Detach the top trim (1) from the bottom (2).
Right: loosening the lever on the column is done by unscrewing the clamping screw located obliquely using a hex socket wrench (arrow) or Phillips-head screwdrivers in earlier year vehicles.
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