Oil Pressure Sender: Testing and Inspection

Oil pressure and oil pressure switch, checking





Special tools, testers and auxiliary items required
^ Oil pressure tester V.A.G 1342
^ Diode test lamp V.A.G 1527 B
^ Adapter set V.A.G 1594 A

Function of the dynamic oil pressure warning indicator

When not under pressure, the oil pressure switch is open and will close when the operating pressure is attained.

The oil pressure warning is activated approx. 10 seconds after switching the ignition on.

Switch-on delay of oil pressure warning approx. 3 seconds.

Switch-off delay of oil pressure warning approx. 5 seconds.

Checking warning lamp
After switching on the ignition and engine not started, the oil pressure warning lamp in the instrument cluster must light-up for approx. 3 seconds and then go out. The test will be terminated if the engine is running.

Criteria for warning

Switching on of the optical oil pressure warning (the oil pressure warning lamp flashes) and the buzzer sounding three times for the acoustical warning will occur under one of the following conditions.
^ "Ignition on", engine not running, oil pressure switch closed.
^ Engine speed higher than 1500 rpm, oil pressure switch open

Note:
^ If the oil pressure switch is closed, the warning lamp will remain switched on if the engine speed is above 5000 RPM. The warning lamp will be switched off again if the engine speed is below 5000 RPM..
^ If the oil pressure switch is open for only 0.5...3.0 seconds when engine revolutions are above 1500 rpm the occurrence will be stored in the combi-processor of the instrument cluster. If this condition happens three times while the engine is running, the oil pressure warning is immediately triggered and remains on, even below 1500 rpm. The oil pressure warning will be cancelled when the oil pressure switch is closed for longer than 5 seconds at an engine speed above 1500 rpm or when the ignition is switched off.

Requirements
^ Engine oil level OK
^ Oil pressure warning lamp -K3- must light up for approx. 3 seconds when ignition is switched on.
^ Engine oil temperature at least 80° C (coolant fan must have run once)

Work sequence





- Remove Oil pressure switch -F1- and screw into tester.
- Screw tester into oil filter bracket in place of oil pressure switch.
- Connect brown wire of tester to Ground (-).
- Connect diode test lamp V.A.G 1527 B using auxiliary cables V.A.G 1594 A to battery positive (+) and oil pressure switch.
- LED must not light up.

If the LED lights up:
- Replace 1.4 bar Oil pressure switch -F1-.

If LED does not light up:
- Start engine and run at idling speed.
- At 1.2...1.6 bar LED must light up; otherwise replace oil pressure switch.
- Increase speed.
- At 2000 rpm and an oil temperature of 80° C oil pressure should be between 2.7...4.5 bar.

At higher engine speeds the oil pressure must not exceed 7.0 bar.

If the specifications are not reached:
Check strainer in suction line for soiling.

Note:
^ Mechanical damage, e.g. bearing damage may also be a cause of low oil pressure.

If no fault is detected:
- Replace oil pump.

If the specification is exceeded:
- Check oil galleries.
- Replace oil filter bracket with pressure relief valve, if necessary.