Oil pressure and oil pressure switch, checking
Function of dynamic oil pressure warning system
Testing warning lamp
The oil pressure warning lamp lights up when the ignition is switched on ("Terminal 15 on") with the engine not running (this does not apply to vehicles with auto-check system).
Conditions for activation of warning
- Engine not running; oil pressure switch closed.
- Coolant temperature above 60° C, engine speed above 1500 RPM and oil pressure switch open.
- When engine speed is above 5000 RPM an active oil pressure warning is not cancelled, irrespective of the condition of the oil pressure switch.
- If the power supply to the control module is ok (Terminal 15) and the oil pressure switch is open for longer than 0.5 seconds at engine speeds above 1500 RPM, this condition is stored in the memory. If this condition occurs three times with "Terminal 15 on", the warning will also become active or remain active at engine speeds below 1300 RPM.
Requirements for test:
- Oil level ok.
- Oil pressure warning light -K3- must come on when ignition is switched on.
- In vehicles with auto-check system the "OK" display must appear (call up symbol).
- Engine oil temperature approx. 80° C (radiator fan must have cut in once).
Testing oil pressure switch
- Disconnect wire from oil pressure switch.
- Remove oil pressure switch and screw in oil pressure tester V.A.G 1342.
- Screw oil pressure switch -2- intoV.A.G 1342.
- Connect brown wire -1- of tester to Ground (-).
- Connect LED voltage tester V.A.G 1527 to oil pressure switch and positive side of battery (+).
- LED voltage tester should not light up.
- If the LED voltage tester lamp lights up, install a new oil pressure switch.
- Start the engine.
- LED voltage tester should light up at 1.2-1.6 bar.
- If the LED voltage tester lamp does not light up, install a new oil pressure switch.
NOTE:
The oil pressure switch may reach its switching point while the engine is being turned over by the starter. It is therefore important to watch the LED voltage tester and the tester lamp while starting the engine.
Testing oil pressure
- Disconnect wire from oil pressure switch.
- Remove oil pressure switch and screw in oil pressure tester V.A.G 1342.
- Screw oil pressure switch -2- intoV.A.G 1342.
- Start engine (engine oil temperature at least 80° C).
- Oil pressure at idling speed: 1.0 bar
- Oil pressure at 3000 RPM: between 3.5 to 4.5 bar
If the specifications are not obtained:
- Replace oil filter bracket with pressure relief valve. Refer to Part II or oil pump. Refer to Oil pump, removing and installing .