Low oil pressure light on-But I have oil pressure?!

[meet07]

Just rebuilt my RB25 and got it tuned. After a short time period I noticed the factory oil pressure light keeps coming on and cutting off. I have an Autometer oil pressure gauge that reads oil pressure all through the rev range. The sender for both factory and aftermarket oil pressures are screwed into the same "T"? So I am confused.....

Any Ideas.

[krash]

The sensor is probably out. Not very uncommon.

[meet07]

What do you mean by the sensor is probably out??

I had an extra one and swapped them out. Nothing happened. Does the sensor work by transferring continuity?? I checked to see if it had power and it didn't. Where does the wire from the dash come from?? The ecu or straight from the sensor??

Thanks Krash

[Hijacker]

The sensor works by grounding the circuit for the dummy light once oil pressure has fallen below 7-8 PSI. The circuit probably has a place it's rubbed through and is intermittently shorting to ground. Just inspect the harness for any areas of rubbing (look up under the driver's front wheel as that's a common spot for tires to rub through).

[meet07]

I have 2 pressure sensors. I figured that with or without pressure the switch should create continuity. I used my ohm meter and pressurized the sensor with compressed air and nothing changed. I also unplugged the sensor while running and jump across the pigtail with a paper clip and nothing???

I will check the harness the best I can. So one wire is ground to the chassis and the other wire goes to the dash??

Thanks Hijacker

[CSUPUEBLOTIM]

Engine start you should have no continuity. Engine stop you should have continuity. Is the RB a 1 or 2 wire sensor?

[meet07]

Engine start you should have no continuity. Engine stop you should have continuity. Is the RB a 1 or 2 wire sensor?

It's a 2 wire. So I was looking the though my Chiltons book, browsing the chassis wiring section and it seems that the pressure switch is a ground coming from the sensor, going to the dash. It flickers but testing the sensor had no change??? jumping the sensor had no change while running??

I may just purchase a new sensor and checked the continuity from sensor pigtail to chassis and see if that shows anything.

[CSUPUEBLOTIM]

so to check your ground just go from the wire ground to a body/chassis ground and see what you get.

[meet07]

so to check your ground just go from the wire ground to a body/chassis ground and see what you get.

Good Idea. Haven't tried that.

[AZhitman]

I'm wondering if having them both on the same "circuit" (because they're reading from the "T") is making the dummy light read low.

In other words, when the pressure activates the gauge, it's decreasing the available pressure in the T, giving the other gauge a false reading.

[meet07]

I'm wondering if having them both on the same "circuit" (because they're reading from the "T") is making the dummy light read low.

In other words, when the pressure activates the gauge, it's decreasing the available pressure in the T, giving the other gauge a false reading.

That would b new. It's been set up this way for 5 years now. I have modified my cluster with 300zx tach and speedometer since the last rebuild. Maybe some how that is playing a factor

[AZhitman]

I'm just thinking, it's kind of like when you have a vacuum distribution block... each "thing" off that block reduces the actual vacuum somewhat, due to hoses flexing, mechanisms moving, etc. Kind of the same reason you run your BOV signal line DIRECTLY off the manifold.