But there is maybe an oil pressure SAFETY switch differing from Oil pressure sensor and oil level sensor? Where would that go? Ugh.
I bet I could Stump the Chump.
I wouldn’t call this a safety feature, I had the same system on a 98 Olds intrigue and was going around a ramp at 85 and the oil got plastered to one side of the oil pan and the computer shut off the engine in the middle of the curve. They should never put this on a car without putting baffles in the pan to keep the oil in place.
Seriously, check that ground connection first that comes from the switch. If that has a bad connection, it would be just like that switch had opened.
That’ll be controlled by the ECU. The protocol will be in the The only way would be to “fool” it, which is essentially what Tester is suggesting. His assumption, and he’s probably right, is that the “level sensor” is a switch that’s open when the level is low and closed when it reaches the minimum. That would be the way these levvel sensors usually wotk.
Without access to an actual schematic, which I unfortunately don’t have, it’s impossible to get very specific.
You all have been very kind and patient with me. I will try the connections on the Oil level switch tomorrow when I have sunlight. If they look ok then I will just replace the harness. I will let you know what I discover. Thank you again!
OK, like I said I have a 95 manual not a 98 but I find it hard to believe it would not have the oil level module in the 98 if it was in the 95 with the same system. I think you’re going to have to check with a a dealer on it for sure though. I don’t believe Autozone will have any listing for it but if you ask them about the 95 and they give you the same answer, they don’t know what they are talking about because its in the 95. I really couldn’t find a listing on any of the GM sites though.
Here is a link to the picture of it anyway. If it has the oil level monitor, it must have the module unless its incorporated into the body control module. At any rate its going to be a GM part or junk yard. You’ve already replaced the oil level switch and if the wires look ok, I’d sure suspect the module being screwy but why that would shut the car off I don’t know so might be worth the $100 diagnostics at the dealer.
The fact that the oil level sensor light comes on only when the car is warm, and it continued to do so when the sensor was unplugged suggests to me that the circuit that is illuminating that light is not being completed by the oil level sensor, so nothing that you do at the sensor (e.g. jumper) is likely to have any effect. It seems more likely that some other warning light is trying to illuminate and providing a ground for the oil level light.
This could get really ugly, because even good wiring diagrams are generally not very specific regarding the wiring in the dash cluster.
I think that the solution lies in ignoring the oil level light and going after the reason why the car stops running. We need to determine whether it is the ignition or the fuel pressure that goes away, and work our way up from there.
After it shuts off, how long until you can restart the car?
I can restart right away. And there is no other light that comes on. We tried diagnostics with an OBD2 scanner and no codes came up.
Again, I suspect that the ECU shuts the fuel pump off if the oil level is not confirmed by the sensor as being adequate in order to protect the supercharger. GM has comonly used this approach on its cars, including on my '72 Vega (that one responded to oil pressure). That is. I suspect, why the engine is shutting down.
The system may even have a “bypass loop” like it has for the upstream oxygen sensor that alows the engine to run irrespective of he oil level signal when it’s cold.
But in the interest of full disclosure I have to say that I don;t have access to the GM drawings or specs, only Toyota’s.
Correct me if I am wrong but if the switch is normally closed that means the switch will have continuity (closed) through it when the oil level is low, and no continuity (open) when the oil level is at proper level. Just saying that because people are telling her to jump out the switch to check it, in which case that would trigger the low oil safety to come on continuously. Simply unplugging the switch should defeat the safety and cause the oil safety not to activate.
You have it backwards. Float-activated on/off switches typically are normall open, and close only when the float reaches the appropriate level. In this case I suspect that the switch never closes, the ECU thinks the level is too low, and it shuts the pump off.
If you look at the wiring diagram that RemcoW posted it clearly shows the switch as a normally closed switch, unless the drawing is wrong
I know when the low coolant level switch went bad on my Impala, and caused the warning light to stay on, all I needed to do was unplug it to get the warning light off. of corse I replaced that little expensive switch and re connected the plug, so all is good.
I am wondering if it is a bad crimp on the ground wire. Since the light does not come on and stay on…it will do this intermittent thing and then suddenly shut down the car. I am reconnecting the wires now.
It seems like too much liability to me to actually shut off the engine if the oil level gets too low. My old Grand Am had a float sensor and would illuminate a light to warn you but didn’t actually create a hazard by shutting down while driving. That was not a switch but more like a hall-effect sensor. The schematic showed it as a switch but it wouldn’t be the first time someone took liberties with interpreting the “function” of a device over illustrating the actual technical means to accomplish it.
The old GM design with a second pressure switch would only shut the motor down within seconds after starting if the oil pressure didn’t come up. This would preserve the engine in the event of insufficient pressure at start up but the function was disabled afterwards.
So it’s surprising to think they would undertake such liability to save your engine and risk being sued off the planet by numerous injury lawsuits from potentially defective (even if they’re not) systems. Providing intervention is a whole different world of liability from simply warning someone of a risk.
That being said, you could easily verify this entire scenario to make sure it’s not a red herring. Unplug the sensor and measure the resistance. You could go the extra mile and verify the other state but probably not necessary. Assuming it has very low resistance and will “open” when oil level gets low, then reconnect the sensor, start the engine and unplug the sensor. If the engine does not shut down but only illuminates the low oil light, you might want to pursue other diagnostic paths…
Americar, I hadn’t looked at that schematic and it appears that you are correct. I wish I could see the other relevant schematics to see if that switch in fact is an input to either the fuel pump or the ignition system.
That depends on how it is drawn. Usually things are drawn in operating condition so if it is drawn closed, it likely means that it is closed when the oil level is normal.
It would make sense too because it makes the circuit ‘failsafe’. That means that, if a wire breaks and the oil level is thus unknown, the car will not start and the condition of the failure is indicated by that idiot light.
There’s an easy way to make sure, though: Try unplugging it and see if the car starts and/or that light lights up. Then try shorting it and see if the car starts and/or light lights up.
Edit: I see now that @TwinTurbo suggested the same thing before the question was even asked - he’s a smart feller. 
He’s right: this could be a red herring and we assume that a low level shuts the car off. Maybe it doesn’t do anything like that. Maybe the low level light is the effect, not the cause.
Folks, we may have a red herring here. According to my book, the oil level switch is normally closed. Three wires go to the oil level module which has a switch normally open. When closed it would signal the instrument panel light. I see no tie in at all either in the schematic or the trouble chart talking about shutting the pump off. There is a oil pressure switch that will shut the pump off but that is separate from the monitor. It also closes when pressure is up to over ride the relay to keep the pump running if the relay fails.
The fact that the light goes on may have nothing to do with the car shutting off when warm. There is an ignition timer off/on listed on the module but have no idea what that is or does. I guess I’d put a test light on the fuel pump test connector, or a fuel pressure guage, to see if the pump loses power when the car shuts off. If so, we’re back to pump, computer, or oil pressure switch. If not we’re back to ignition module, computer, crank sensor, coil, or who knows.
She already replaced the oil level switch so that really shouldn’t be a problem at all.
Addendum: Looking at Remcow’s schematic, that’s different than mine but I’m three years older so don’t know. However if there are only two wires and the signal wire goes to the PCM (Powertrain Control Module), then I 'spose you could have a faulty PCM. That still doesn’t seemt to answer why the engine would shut off.
So I guess I’d do the test to see if the pump is shutting off or not.
I copied this from the 1998 Pontiac owners manual, I expect that Buick is the same;
The oil level monitoring system only checks oil level
during the brief period between key on and engine
crank. It does not monitor engine oil level when the
engine is running. Additionally, an oil level check is
only performed if the engine has been turneodff for a
considerable period of time, allowing the oil normally in
circulation to drain backin to the oil pan