This was the test I carried out on mine and I also checked oil pressure which I now believe to be the issue.
A. To test the high pressure sensor circuit and wiring (sensor for this is on the oil filter housing):
1. Disconnect the wire to the high pressure sensor on the filter housing and let it float (un-connected).
2. The oil buzzer should now come on and indicator will flash when the van engine speed is above 2000 RPM.
3. Now connect the yellow wire to ground and rev the engine past 2000 RPM… the buzzer should not sound at all.
4. If you fail either of these tests you have sensor issues, wiring, alternator wiring, or instrument cluster issues.
To test the sensor itself:
A test light between the sensor and the positive battery terminal should be 'off' at warm idle and come 'on' as you rev to 1800-2k RPM, if the sensor on the flange is working properly. If the buzzer still sounds with the wire to the sensor grounded the problem is most likely the wiring to the instrument cluster.
B. To test the low pressure sensor (sensor for this is on the cylinder head):
1. Disconnect the wire to the sensor and leave it float.
2. Connect a test light between +12V batt and the sensor.
2. Start the van and leave it idle - the light should go off - if it doesn't the you have a faulty sensor.
3. If it does and the oil light is still flashing then you have either a wiring fault or the engine speed signal from the alternator is missing.
So, the long and short is:
A flashing oil light, on its own at engine speeds of
A flashing oil light and buzzer are both a function of the high-pressure sensor on the filter housing. If this is happening you should look at the high pressure sensor and associated wiring
The high pressure sensor on the oil filter flange is only monitored when the engine is running at or over 1800-2000 RPM.
A flashing oil light at all engine speeds (and without buzzer above 2k RPM) is indicative of a missing engine speed signal (alternator 'w' terminal) - check to make sure that the instrument cluster is getting the correct engine speed signal from the w terminal of the alternator
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