Audi 80/Avant (B4)

Since 1991-1995 of release

Repair and car operation

The indicator of pressure of oil

Pressure of engine oil in Audi 80 is supervised by two switches with a hydrodrive and the block of management with a buzzer (both last are combined in minicheck system). If to represent упрощенно the control is carried out as follows:

At the included ignition to one of contact conclusions of the indicator of pressure of oil a food constantly arrives.
If pressure of oil (at the idle engine) more low 0,3 bar — contacts of the switch to a hydrodrive 0,3 bar thanks to what connection on "weight" to the second contact conclusion of the indicator is created become isolated – the lamp lights up (blinks).
If after the beginning of work of the engine pressure of oil rises, contacts in the switch open, and the lamp dies away.
The additional control is carried out on models with 4 and 5-cylinder engines by means of the switch with a hydrodrive 1,8 bar, on models with the 6-cylinder engine by means of the switch with a hydrodrive 2,5 bar.
The switch with a hydrodrive and the management block is included into minicheck system: if pressure of oil falls below switching pressure 1,8 or 2,5 bar its contacts become isolated, creating thereby connection on "weight" to the management block in minicheck system – the switch with a hydrodrive 0,3 bar at this time also does not join.
The minicheck system allows an indicator lamp to flash only in a case when pressure of oil falls below switching longer, than on 1 with and the number of turns of the engine thus makes more than 2100 rpm.
In addition the minicheck system publishes a precautionary noise signal. Sense of all of it in prevention of damages of the engine because of too low pressure of oil (for example because of its too low level).

Switches with a hydrodrive

At the left: the 4-cylinder engine: both switches with a hydrodrive 0,3 bar (1) and 1,8 bar (2) are located on a flange of the oil filter (3).

On the right: the 5-cylinder engine: switches with a hydrodrive 0,3 bar (1) and 1,8 bar (2) are located at the left at the engine below the thermostat case.

At the left: near to a pulley of a cranked shaft on models with the 6-cylinder engine the gauge of the indicator of temperature of oil (1) is located. Directly near to it the switch with a hydrodrive 2,5 bar (2) is visible. Behind it the switch with a hydrodrive 0,3 bar is located. On the models equipped with additional devices, the switch 0,3 bar is united with the gauge of pressure of oil.

On the right: in it штекерном the connection (marksman) located behind at the left head of the block of cylinders, all wires to the gauge of temperature of oil, the gauge of pressure of oil and both switches with a hydrodrive are collected.

Insulators of switches with a hydrodrive are painted in different colours.

The switch with a hydrodrive 0,3 bar is painted in brown colour. The cars equipped with a manometre, on a place of this switch have a gauge of pressure of the oil, supplied with in addition switching contact for the indicator.
The switch with a hydrodrive 1,8 bar is painted in white colour (models with 4 and 5-cylinder engines).
The switch with a hydrodrive 2,5 bar is painted in red colour (models with the 6-cylinder engine).

Search of malfunctions

PERFORMANCE ORDER

If the indicator flashes (probably with an additional buzzer) at the working engine, it is necessary for you to stop immediately!
Immediately to muffle the engine, to check up oil level. If it in norm:
To disconnect a wire from the switch with a hydrodrive 0,3 bar, to leave it to be groundless, include ignition: if the indicator continues to burn, it means that in conducting there was a short circuit on "weight" – is harmless for the engine.
To disconnect a wire from the switch with a hydrodrive 1,8 bar (or 2,5 bar) and to bring to "weight", to include ignition: if the indicator continues to burn or the warning buzzer continues to sound, means, malfunction concerns minicheck or check systems – is harmless for the engine.
If you observe others, not resulted above, effects it is possible to suspect that supply of the engine by oil is broken. Further the car is necessary for towing!
Probably, one of switches with a hydrodrive is faulty. Sometimes it again joins if to shake it штекерный a uvula.
If the indicator of pressure of oil does not flash after ignition inclusion:
At first to check up a safety lock (head Kuzovnaja electrosystem).
To disconnect a wire from the switch with a hydrodrive 0,3 bar and to bring to "weight": if now the indicator lights up, means, the switch was faulty. If it still does not react, means, conducting or a bulb are faulty.

Check of the block of management

PERFORMANCE ORDER

To disconnect a wire from the switch with a hydrodrive 1,8 bar and to leave it to be groundless. To get the engine and to leave to work at frequency about 2500 rpm.
After 2 seconds of work the indicator and three times should flash to sound a buzzer. Otherwise the minicheck system is faulty – to replace!
If the indicator flashes only, but does not work a buzzer, means, conducting from the plug of the generator 61 (D +) is interrupted.
If the indicator flashes and the buzzer is distributed at the connected wire to the switch with a hydrodrive at frequency of turns of the engine about 2500 rpm, means, the switch 1,8 bar (2,5 bar) – provided that level of oil of the engine as it should be is faulty.
To leave the engine to work on single turns, to disconnect a wire from the switch 1,8 bar (or 2,5 bar) and to leave to be groundless. If the bulb and a buzzer now work, means, conducting from the plug 1 (a signal of frequency of rotation) and minicheck systems is interrupted.

Replacement of the switch with a hydrodrive

PERFORMANCE ORDER

To get the necessary switch with brown, white or red isolation and one sealing ring.
To tighten the switch with a hydrodrive the moment 25 Н•м.

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