So my brother inherited my '90 Integra, and the oil pressure light came on after it had sat idle for almost a year. He replaced the oil pressure sensor/switch, and changed the oil/filter. Right after that, the oil light goes through every conceivable state, on, off, blinking, flashing, barely lit, constantly lit. It briefly went off after an oil top off, but then started up again. The lamp does not change when going over bumps.
So, bad sensor? Bad wiring with the sensor? Bad wiring for the indicator lamp?
Has anyone seen this problem before? My brother swears that the sensor was installed correctly, and I suspect an issue between the sensor and the indicator lamp.
I’ve never had the exact problem, but considering the ramifications of low/no oil pressure, I’d recommend getting to the bottom of it. As I see it, the best solution/diagnosis will come from the installation of a mechanical (vs. electrical) oil pressure gauge. The installation need not be permanent, although it’s not a bad idea.
In my world of domestic V8 engines this would be very easy and inexpensive. The existing oil pressure sensor would be replaced with the sensor that comes with the new gauge. If installation was to be temporary I’d simply run the tubing from the sensor to the gauge which I’d hold in my hand. Fire the engine and you’ll know immediately whether there’s a problem.
The mechanical gauge, by it’s very nature, is very simple and it would bypass all the electrical variables.
First, I would make absolutely certain that it has the correct oil pressure switch. I could see one designed for a gauge causing a light to act up like that. Next, I’d look for obious damage to the wiring. A car that has sat for a while is a prime candidate for rodents gnawing on a wiring harness. Next would be to test the oil pressure with a mechanical test gauge. If it has the right switch, no obvious wiring damage, and correct oil pressure, then it’s time to do some electrical troubleshooting and/or install a new wire between the switch and the light.