oil warning light

[Flat on my back]

.



Well that works for you...

[S2central.net]

Yes - the 'cotton reel' one is labelled G for signal to the guage and the other wire pin is for 0.3bar switch. The separate white sensor is 1.8bar switch.

I did once make a start on a 'how to' test these boogers to help isolate problems between autocheck, sensors and the loom itself. I'll see if I can dig that up.

Those 'cotton reel' jobs are a stupid expensive price for what they are - circa 60 quid and more - tis ridiculous so you dont want to be changing one for fun - plus they are a total beeatch to remove from an S2/RS2.

[S2central.net]

FLuky extract from the /dev folder

DISCLAIMER though that I haven't looked at this in ~2yrs so proceed carefully - logic needs to be checked on a few cars really...



Testing the 0.3bar Oil Pressure Switch (F22)

Pre-Requisites

This is one of two oil pressure switches that present information to the Autocheck module. This one, activated at 0.3bar, is relevant at all engine speeds as it represents catastrophic failure of the oil pump, or near total loss of oil itself.

This can be tested a couple of different ways. Curiously, Audi use some weird logic on this signal such that if the F22 switch (shown below) fails or the wiring is open circuit, then no alarm condition is identified. I would personally much rather have the logic such that the switch in the open position would represent an alarm to avoid the silent failure scenario of the wiring loom or pressure switch from masking a real oil pressure alarm.


Method 1 – Test F22 itself

With the engine off, the electrical switch within F22 should be closed… Showing zero ohms on a resistance test across the contact on the switch and the block as shown below.

When the engine is running, assuming oil pressure exceeds 0.3bar (which you can validate with the oil pressure gauge in the centre console) then the F22 switch opens. These two conditions can be quickly tested with a resistance test of the switch. Failure of this test indicates a faulty pressure switch.


Method 2 – Autocheck and F22 Connectivity

Disconnect the electrical connection to F22. Start the engine and verify that no oil pressure alarm indications are active on the cluster– doesn’t inspire confidence does it? Then connect the electrical plug for F1 to ground, with a suitable jumper cable to the block and verify that the oil pressure alarm is activated on the cluster.

If this test fails, then verify that pin 19 on the WHITE Autocheck connector switches to 0V when the jumper at the F22 connector is pulled to ground.

[S2central.net]

And for completeness... extracted from same unreleased /dev info on the other sensor...


Testing the 1.8bar Oil Pressure Switch (F1)

Pre-Requisites

This is second of two oil pressure switches that present information to the Autocheck module. This one, activated at 1.8bar, is only relevant at engine speeds in excess of approx 2800rpm. The reason for this is so as not to provide an alarm indication at low engine speeds with hot oil – although its fair to say this behaviour would indicate an oil pump that is definitely past its best.

This switch, like its 0.3bar counterpart, can be tested a couple of different ways. Unlike the 0.3bar switch, this one is wired with much better logic in that a failure indication is presented by a short-circuit connection to 0V. This way, a disconnected switch, or faulty wiring shall raise an alarm.


Method 1 – Test F1 itself

With the engine off, the electrical switch within F22 should be OPEN circuit when testing it in isolation as shown below.

When the engine is running, assuming oil pressure exceeds 1.8bar (which you can validate with the oil pressure gauge in the centre console) then the F22 switch should be seen to CLOSE to 0V. These two conditions can be quickly tested with a resistance test of the switch. If this test fails then it indicates a faulty pressure switch.


Method 2 – Autocheck and F1 Connectivity

Disconnect the electrical connection to F1 by removing the spade connector. Start the engine, letting it idle, and verify that no oil pressure alarm indications are active on the cluster.

Then raise the engine speed to approx 3000rpm, leaving F1 disconnected, and verify that the oil pressure alarm is activated on the cluster.

If this test fails, then verify that pin 17 on the WHITE Autocheck connector follows the behaviour described in Method 1 above to verify the wiring to F1 is good. Easy with the breakout box and the right adapter, but equally achievable with care and a bent paper clip to access the pin in question.


HTH,

Paul

[Pirvu Eugen]

How does the system gets the rpm signal?
At the old models without the board computer i know it has a relay wich controls the 1.8 barr swich wich need a high voltage rpm signal from coil, not from the taho signal from ecu.
At the board computer ones....how is working?
Thank You!
Eugen

[Error404]

So basically Paul, unplug the connector to the sensor and the alarm should go away indicating the sensor is playing up?

[Pirvu Eugen]

The wire from wk pin should be disconected.....iff the alarm goes out....is the sender.
the wire from the single white sensor should be grounded. Iff the alarm is still on...then the cluster or wiring is the problem.

[Error404]

I'll have a look at that later tonight

[pixsaudisex2]

you did put the wires back on the right way..

[Error404]

haven't taken them off yet

they're on the right way i just think my cotton reel is fooked

[pixsaudisex2]

haven't taken them off yet

they're on the right way i just think my cotton reel is fooked

I was on about to the orginal poster,,,,,,


I only know this as i once messed the wires up .

[Error404]

I got to the bottom of this and it was the "cotton reel" pressure sender playing up - unplugged the rubber sleeved connector and hey presto the bleeping and flashing stopped. Just got to work out how the f*** i get it off now to fit a new one - looks like rad out and "modify" a 99p spanner for the job again

Any BTDT on this with engine in situ?

[johne]

I did it by leaving the radiator in - I didn't want to do all that coolant and possible A/C draining/refilling bit - and removed the hydraulic pump instead and went in that way.

"Cotton reel" wasn't all that tight as I recall.

Strongly suggest you replace the 1.8 bar oil pressure switch next to the cotton reel whilst you're in there as it's a well deserved reputation for leaking and isn't that expensive but of course just as much of a pain to get to.

John

[S2central.net]

I've never managed to change one of those without radiator removal - they have always been stupidly tight IME and access is very limited.

[PeteUr]

Yup the cotton reel one's something like a 19mm spanner and isn't that tight, easy to un-do.