Driving home tonight and the oil light came on Alarm bells rang out loud. Pulled over asap pulled lid off, all dry no leaks, water pipes at a good temperature. Checked oil half way between marks so drove off gingerly. Oil light then started flashing on and off. Then went off all together for ages then came on and off and flashing then off then on then off and didn't come back on.
Ok so with a ‘88 you have two oil pressure switches, one tween the push rods , which is basically for the low oil level / oil light and the other is down behind the water pump pulley , top of the oil filter , which is low pressure .
Both have brown wires which go from the switches to a white twin spade connector going to a yellow/red wire for the low pressure and a blue/black for the oil light, into the black box in the engine bay and then into the loom …….
First visually inspect the wiring in the engine bay , looking for damaged insulation and horrible green corrosion . Then check the connectors on each end of the brown wires for corrosion …….
Assuming all those checks find no faults, take the brown wire for the switch tween the push rod tubes and make it connect to ground ( engine / chassis ) the oil light should be either on , or off as you connect , disconnect .
The low pressure switch should only cause the oil light and buzzer to sound when the engine is above 2000rpm , so concentrate on the one tween the push rods
Well I have had a chance this afternoon to have a look and can confirm that both of the wires to the two switches are making contact all the way to the black box and that both are earth with ignition off.
Assuming this is all how it should be then I guess as you say I need to be trying a new switch.
Not sure how you would test the pressure?
I get the bit about buying a good one! BW I guess?
From your original description i would get the switches changed before i spent out on a oil pressure check , oil pressure wouldnt have healed itself on the same journey i dont think , sounds like a electrical issue to me .
First rule of diagnosis is start at point “A” and move in a logical direction, always check out the lowest cost option rather than throw money about …..
Both switches shouldn't be closed with engine off, one is normally closed (blue, between pushrod tubes) and the other normally open (closes under pressure, either 0.9 or 1.8 bar, depending on stuff). Start engine, pressure opens blue switch, light goes out. Rev engine, if white/grey switch closes before 2000 rpm then no light or buzzer. If the BOD circuit doesn't see a closed switch at revs it'll shout up.
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Yes, but not enough to cry over , thats said , dont take forever , one out one in asap .
Take care when ordering new ones that you get the correct one…….. brickwerks , not crap car parts is my advice
You’ll need a long 24mm socket. You can do it with normal length socket you just can’t ‘house’ the ratchet lever because the spade terminal from the sensor will be there.
2005 Porsche 911 3.6 Manual
2012 Volkswagen Polo 1.4 Automatic
Alarm bells rang out loud. Pulled over asap pulled lid off, all dry no leaks, water pipes at a good temperature. Checked oil half way between marks so drove off gingerly. Oil light then started flashing on and off. Then went off all together for ages then came on and off and flashing then off then on then off and didn't come back on.
