Oil Pressure Sender: Testing and Inspection
Oil pressure and oil pressure switch, checking
Special tools, testers and auxiliary items required
^ Oil pressure gauge V.A.G 1342
^ Voltage tester V.A.G 1527B
^ Adapter set V.A.G 1594C or V.A.G 1594A
Function of the dynamic oil pressure warning system
The oil pressure switch is open at no pressure and closes when the switch pressure is reached.
The oil pressure warning will be activated approximately 10 seconds after switching ignition on ("terminal 15 on").
Switch-on delay of oil pressure warning: Approximately 3 seconds
Switch off delay for oil pressure warning: Approximately 5 seconds
Warning lamp check
After switching on the ignition and not starting the engine, the oil pressure warning lamp in the instrument cluster must light up for approximately 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
^ At engine revolutions greater than 5000 rpm the oil pressure warning will not be triggered, even when the oil pressure switch is closed.
^ If the oil pressure switch is open for 0.5 to 3.0 seconds when engine revolutions are above 1500 rpm, the occurrence will be stored in the 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 goes out when the oil pressure switch is closed for longer than 5 seconds when engine revolutions are greater than 1500 rpm or the ignition is "switched off".
Requirements
^ Engine oil level OK, checking
^ Oil pressure warning lamp -K3- must light up for approximately 3 seconds when ignition is switched on.
^ Coolant temperature at least 80 °C (radiator 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 voltage tester V.A.G 1527B using auxiliary cables V.A.G 1594C to battery positive (+) and oil pressure switch.
- LED must not light up
If LED lights up:
- Replace Oil pressure switch -F1-.
If LED does not light up:
- Start engine and increase speed slowly.
- At 0.55 to 0.85 bar LED must light up; otherwise replace oil pressure switch. Increase engine speed further.
- At 2000 rpm and an oil temperature of 80 °C oil pressure should be: minimum 2.0 bar
- At higher engine speeds oil pressure must not exceed 7.0 bar
If the specifications are not obtained:
- Check strainer in suction line for soiling.
Note:
^ Mechanical damage, e.g. bearing damage may also be a cause of oil pressure that is too low.
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.