2G Oil pressure switch operation?

[1LE]

Should the oil pressure light come on when the oil pressure switch is disconnected?

The backstory:

I noticed my oil pressure gauge was getting "stuck" down near the bottom (it actually no longer drops all the way to the bottom when off) in the mornings. Didn't think to much of it at first because a) DSMs have an oil pressure light, b) my fuel gauge also does the same thing so it's probably just the aging combination meter, and c) I've actually lost oil pressure on this car before and it's obvious as it sounds like a box of rocks in a blender... Then one day I actually watched the dash lights as I went to "on" and then "start" with the ignition. I observed that the oil pressure light did not come on at any point...

First guess was that the light had just burned out in the dash, and the combination meter is easy to pull, so I did. The oil pressure bulb looked perfectly fine, but when I put it in other locations, then those didn't light up anymore. So, looks like probably a bad base or perhaps a bulb that isn't working despite looking fine. I then swapped my (working) SRS bulb over to the oil pressure socket. Still no oil pressure light during the power on self test. Swapped it back. Yep, works in the SRS slot. Back to oil pressure. Nope. Cleaned all the connections and played the bulb hokey-pokey again. Still no luck. Well, gee, apparently I have a bad bulb/base AND something else wrong.

So, I popped the car up in the air and pulled the wheel off so I could get the shield off, so I could pull the brake duct out of the way and actually get at the switch. Maybe the switch is stuck in the "pressure detected" position. Unplugged the signal wire and let it dangle, still no light... I really expected the light to come on. If "no signal" means good oil pressure detected, which would be quite a counterintuitive way to design the car, then I might just need a new pressure switch. However, if "no signal" means bad oil pressure and that the light *should* come on, then the switch may well be fine and I should look elsewhere for some other problem...

 

[1990TSIAWDTALON]

Ground that wire and your light should come on. When no oil pressure is detected, it grounds the sensor.

 

[1LE]

Thanks!

Well, appears there's a problem elsewhere... No light with the wire grounded. I guess it's going to be fun with wiring time... Or maybe just time for an aftermarket oil pressure gauge setup...

 

[1990TSIAWDTALON]

I have both. I will ground mine just to make sure the light comes on as a test. Really the factory oil pressure gauge is very slow reacting so a aftermarket one will give you a better idea of the true pressure. What year is your car?

 

[Chumpaumpalumpa]

Wait wait. Maybe I'm not understanding this right, but are you trying to get the light to come on with a known bad base/socket?

 

[1990TSIAWDTALON]

I THINK he is testing the "dummy" light for functionality.....I know when my oil filter came loose my light didn't come on when my pressure was at zero, it hesitated and flickered JUST as I turned the car off...which had NO oil pressure.

 

[1LE]

It's a '95 (October '94 build date, so has the different rear brakes, etc.).

I've got a known good bulb & base in the oil pressure light slot now (unless it suddenly failed now too!). I found that the old one was bad by trading with other locations.