Another oil warning light

[937carrera]

Wiring diagram here

https://www.thesamba.com/vw/archives/in ... iring3.jpg

This is for the US Aircooled, but should be the same up to the point the DOPS was introduced. There are early WBX wiring diagrams also on the Samba, but confusingly they refer to a 1.8 bar switch, when the one between the pushrod tubes is 0.3 bar.

Also have a read here

https://www.brickwerks.co.uk/brickwerks ... -switches/

The easy test I described above is the quickest way to check the wiring out, though from what I can see that black wire looks thicker than I would have expected

[Mr Bean]

Unless I am missing something here (This is not impossible ) and assuming that the switch is a normally closed device, I don't see any mention of the simple test of switching on the ignition and touching the switch wire onto the engine block while someone watches the oil warning light in the nacelle.

[sharpmz]

Here's the new switch....

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[937carrera]

Unless I am missing something here (This is not impossible ) and assuming that the switch is a normally closed device, I don't see any mention of the simple test of switching on the ignition and touching the switch wire onto the engine block while someone watches the oil warning light in the nacelle.

Yep, did that in post 11, job for the morning I think



Looks like the correct normally closed oil pressure switch, so looks like my original theory is out of the window, let's see how the easy test goes.

... and then check where the black wire goes back in the loom to the junction box

[sharpmz]

So... The oil pressure switch is currently hooked up to the black wire which is live. When I separated the connection and earthed it there were a few small sparks a little crackle and my heart rate increased a bit!
This needs resolving and looking at the (i think it's the) water sensor just to the right in the image of the wire in question (if you turn the pic to landscape sorry).
This wire is blue and black and has the same yellow block.
So I tried connecting this but then there was no light at all?
Hmm feels like one step forward, 1 and a half back.

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[937carrera]

What happened to the oil light when you simply disconnected the wire to the switch ?

[sharpmz]

It stays on! [DISAPPOINTED BUT RELIEVED FACE]

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[sharpmz]

Ah smileys don't work then!

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[937carrera]

So the black wire that goes to the oil pressure switch is doing nothing, the circuit to allow the oil light to come on (i.e a route to earth) is elsewhere.

It looks like someone's been messing

I suggest you do a couple of things:

1. Try and find out where the black wire goes in the junction box - take a photo for us to help
2. Do the same for the black/blue wire, back to the junction box and also where that is connected to

Leave the black wire unconnected for now, we'll deal with that later

Do you have a multimeter ?

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[sharpmz]

Looking at things "messing" is spot on!
Ok, so 1st pic...
Looks like the wire goes back to here and is the yellow connection closest to the camera.

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[Pat4d]

I'm just reading through this with interest.

Am I right in saying that there is a live feed going to the oil warning light, this light is then earthed through the engine via the switch, thus putting the light on. When the switch senses pressure it breaks the contact to earth and therefore the light goes out.

If this is correct then the cable going to the switch will indeed be live at all times with the ignition on.

The original problem is that the light stays on for 5 mins when cold but goes off and acts normally when the engine is hot. Oil pressure test has been completed and is good, was the engine hot or cold for this? I am asking this because we may be getting distracted from another problem by looking only at the electrical side.

Hope my though process makes some sense.

Regards,

Pat.

[937carrera]

Pretty much.

The oil pressure is OK, so that is not a problem to worry about. I'm beginning to think that the oil pressure and carb heater wires are swapped, which is why I have suggested the wires are traced. I'm not near an engine to look at, but others may just know. The oil light is a simple circuit, and can be simply tested electrically.

[937carrera]

I'm with both of my vans now.

My WBX is a late version with DOPS, but I believe the low pressure wiring is unchanged in the engine.

It is a blue / black cable, terminal 1 in one of those 7 pin connectors. This goes into the loom and then exits in a small sub loom which exits from the bottom of the chassis and heads off to the thermostat housing / gearbox.

The blue / black wire exits at that point as a loose wire and on factory wiring then goes to a connector which connects to the oil pressure switch with a brown wire.

I would have done a photo but my phone's dead - there's a lot about your engine layout I don't recognise, maybe it's just the early cooling system

[937carrera]

Charged up now, hope this helps. Finger is over the connector, thumb keeping the king lead out of the way. Not declaring mine as being an example of unmodified wiring

[sharpmz]

Awesome thanks! Sorry for the silence..... have had anniversary today so couldn't get away with working in the van!! Will get kids to bed and then get out and start sorting through your previous messages. Thanks so much for your help so far!! Feeling positive about getting it sorted!

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