Oil Pressure Sender: Testing and Inspection

Oil pressure and oil pressure switch, checking

Special tools, equipment, testers, measuring instruments and auxiliary items required





^ VAG1342 Oil pressure tester
^ VAG1527B Diode test lamp
^ VAG1594A Adapter set

Function of 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 is activated approximately 10 seconds after switching the ignition on ("terminal 15 on").
Switch-on delay for oil pressure warning: approximately 3 seconds
Switch-off delay for oil pressure warning: approximately 5 seconds

Checking warning lamp
After switching on the ignition when the engine is not running, the oil pressure warning lamp in the instrument cluster must light up for approximately 3 seconds and go out again. The check is terminated if the engine is running.

Criteria for warning
The optical oil pressure warning switches on (the oil pressure warning lamp flashes) and the buzzer sounds three times for audible warning under one of the following conditions.
^ "Ignition on", engine at rest, oil pressure switch closed
^ Engine speed higher than 1500 rpm, oil pressure switch open
At an engine speed greater than 5000 rpm the oil pressure warning is not erased; even when the oil pressure switch is closed. Oil pressure warning goes out below 5000 rpm.
If the oil pressure switch is open (engine revs greater than 1500) for 0.5...3 seconds, this is 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; Refer to Oil, testing and inspection
^ Oil pressure warning light -K3- must light up for approximately 3 seconds when ignition is switched on
^ Engine oil temperature at least 80°C (coolant fan must have run once)

Note: Functional check and servicing the optical and acoustic oil pressure warning:

Refer to Wiring Diagrams





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 VAG1527B using auxiliary cables from VAG1594A 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 the LED does not light up:
^ Start engine and increase revolutions slowly.
At 1.2...1.6 bar LED must light up
If the LED does not light up:
^ Replace oil pressure switch.
^ Increase engine speed further.
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 attained:
^ Correct mechanical damage, e.g. bearing damage.
^ Check O-ring of sealing plug for damage.
^ Replace oil filter bracket with pressure relief valve or (for engine code BDC, BGD) oil pump with balancer shaft gear assembly.
If no failure was found:
^ Replace engine pump
If the specification is exceeded:
^ Check oil galleries.
^ If necessary, replace oil filter bracket with pressure relief valve.