jschick

I have this 99 1.8t that has a flickering oil light. I am only aware of 1 sensor on this car which is the single wire sensor on the oil filter housing. But it makes no difference if this sensor is plugged in or not I still get the flickering oil light between 1500 and 2500 rpm above and below it's fine?

4Driver4

It either needs a pump or it's sludged.

jschick

but it still does it with the sensor unplugged?

eCoastAudi

I think the sensor is normally closed (shorted) and opens when there is bad pressure. But try grounding the sensor wire and see if there is any difference in the light. If there is, you may have a bad sensor (or you could still have an engine problem). The sensor is $8 at AutoZone and would be worth trying. You can also measure your actual oil pressure. Make sure the spade connector on the wire is tight when plugging it into the sensor.

jschick

well I grounded the wire and didn't have a chance to drive it yet but when you start the car the oil light is off, I figured it would be on??
if you just turn on the ign key and don't start it after 30 seconds the light comes on, then if you start the car the light says on for a few seconds and then goes off.

so for now, I have replaced the sensor with no change, with the sensor plugged in or unplugged no change, it does not matter if the wire is plugged in or not the light still acts the same. and with the wire grounded out the light does not stay on when you start the car, but haven't had time to drive it to see if it stays out. and by testing my old sensor it is shorted out with no pressure, so I would assume the light would come on with the wire grounded out?
So what gives here?? anyone know anything about the oil circuit wireing??

thesameguy

This is how it should work. Oil pressure opens the sensor, turns the light off. No oil pressure shorts the sensor, light on. Or, that's how it should work, anyway.

With the connector off the sensor, and not touching anything, there is no way the oil light should be able to go on. With the connector shorted directly to ground, the oil light should stay on.

The switch shorts out below ~1.4 bar, and opens above that. That said, I believe there may be some logic in the idiot light that keeps it off below a certain RPM but I don't know for certain. Maybe someone else can confirm or deny that. If there is, perhaps that system is broken on your car and that's why you're getting the light?

jschick

that was what i am assuming, I am pretty sure I have good oil pressure, I have not put a gauge on it, but I have had the valve cover off and their was no signs of lacking oil, my Real concern is the fact that with the sensor unplugged and wire taped, the light should not come on! but I get the exact same light with the sensor plugged in or unplugged. and when it is grounded I would assume the light would come on and stay on, but it doesn't, unless you leave the key on and not running, then the light is on.
I did swap out ECU's with no change as well but I didn't expect the ECU, I get no vag faults under instruments, so what next any Ideas????

jschick

well i did find out their is a Oil pressure control module which is part of the gauge cluster, and I guess when they fail this is what happens, so i guess I will pull the gauges out and take a look

thesameguy

That makes sense - I was pretty sure that there was some electrical doodad which managed the light other than the switch.

I am not sure if that doodad is discrete and can be replaced separately though - I think it's like an anti-slosh circuit and built into the cluster. I could be wrong though!

jschick

I removed my gauges and it looks to be a seperate module that plugs in. You do need to dissasemble the gauges to get to it though and i did not dissasemble it. I will run to the salvage yard and see if they have one first.