Syncro Oil Pressure Sensors - Out of ideas...

[MKAkland]

Hey there van humans!

I have an 86 Syncro with lots of problems, its pretty great... but this latest issue has got me scratching my head. I'm no professional mechanic, just a van aficionado that pretends to be.... just as a disclaimer.

Yes, I used the search... and this seems to be a unique problem.

I recently replaced my printed circuit board behind my cluster with the Gowesty upgrade (its pretty slick, I gotta say) but after finishing the installation, my oil pressure light and alarm go off. The following morning I changed my oil to 20W50, put on a new Mann oil filter, and nothing changed.

Specifically: the oil light comes on once I start the engine, and stays on. Once I reach ~2200 RPMs, the audible alarm rings.

I unplugged the (low) oil pressure switch's wire and grounded it, and the light on my dash still did not go out. (Thats how you test if the wire is good, right?) As far as I can tell, the sensor wires (that are visible in the engine bay and behind the dash) are not corroded or broken in any way.

The plot thickens....

So I'm driving around the block for a test drive, the oil light is on... I pull up to a stop sign, slightly lug the engine on accident for a second as I hit the brake... and the oil light goes out!! I hit the clutch in excitement, and the light turns back on.... damn.

I've found out that if I feather the clutch when in a high gear, I can intentionally make the light go out, but it comes back on once I get into a normal gear/push the clutch in all the way.

WHAT IS GOING ON?

I guess I could follow the wires that go from the dash all the way to the engine bay, but I was hoping to find inspiration on thesamba before tearing up the thick hose of wires under the van...

Side question: if I unplug my oil pressure sending unit (the one on the driver side of the engine) will my oil just drain out? I was thinking about testing my oil pressure, but dont want to just waste all the oil I just filled the engine with. I screwed up that order of operations.. I know.

I still need to test the high pressure switch, but I figured I should find the break in the system before moving onto the next problem...

Please help!!!!! And happy turkey day.

Thanks,

Mike

[drj434343]

Assuming you didn't have this problem before the GW circuit board conversion, I would say that's a big clue.

I recall there is a dip switch you have to flip depending on what kind of oil pressure circuit your Van has. Check the installation directions. I recall being a bit confused by them and what position to put the dip switch. I got it wrong the first time, and got all sort of strange behaviors out of the cluster.

[MKAkland]

[narendra.vw]

I think better have a Oil pressure meter to be on safer side. at least you know oil pump is working. later you can check electrical circuit of the cluster.

[djkeev]

STOP DRIVING YOUR VAN!!! At least until you hook up a gauge and verify engine oil pressure.

Just maybe you've had low oil pressure for a long time, your now good cluster wiring has enabled the gauges/warning system to work as designed.

Dave
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[MarkWard]

Or, you have a cluster from another year/vehicle or someone physically disabled the oil pressure system with the old cluster foil. Low pressure switch must have ground engine off. Engine running, low pressure switch opens and ground goes away. High pressure switch must be open engine off and no ground. Engine running high pressure switch must have ground. You can test both circuits at the cluster T14 connector with a simple testlight connected to power and the connector unplugged.
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[Tom Powell]

[crazyvwvanman]

You need to have the 2 switches wired to the right wires for the cluster. It sounds like you have the high switch wired to where the low switch is supposed to go.
IT MATTERS a lot!

The switches work OPPOSITE to each other.

The low switch GROUNDS when pressure is too low.
The high witch OPENS when pressure is too low.

The stock wiring has a brown wire coming from each switch so it is easy to mix them up where they connect to the main harness colored wires in the engine compartment.


Mark

[MKAkland]

Problem resolved! The previous owner wired the sensors backwards, and disabled the alarm in the old instrument cluster foil. Now I'm on the lookout for more silly things that they did!

Thanks yall!

[quote="crazyvwvanman"]You need to have the 2 switches wired to the right wires for the cluster. It sounds like you have the high switch wired to where the low switch is supposed to go.
IT MATTERS a lot!

The switches work OPPOSITE to each other.

The low switch GROUNDS when pressure is too low.
The high witch OPENS when pressure is too low.

The stock wiring has a brown wire coming from each switch so it is easy to mix them up where they connect to the main harness colored wires in the engine compartment.


Mark