Oil pressure light not working/iluminating

arrrxivvv · Post by **arrrxivvv** » 25 Feb 2021, 14:30

It seems that my oil pressure warning light is not working. It was working till last week.

When turning the ignition to II, all the warning lights turn on, except for the oil pressure light.

I assume that at this stage, it's the DIM checking if the bulbs are working, so it shouldn't depend on the status of the switch? That is even if the switch is faulty or disconnected it should still come on at this stage?

I have checked that the oil pressure switch is connected, and no obvious damage to the wiring.

If it's the bulb on the DIM, from some youtube videos it seems that on P2 cars those are surface mounted LEDs. Is there instruction on how to replace it, and where to buy the LEDs?

Post by **jonesg** » 01 Mar 2021, 13:18

I would go in there and use a meter or computer safe probe test light, no sense soldering if it isn't getting voltage.

Post by **RickHaleParker** » 01 Mar 2021, 13:50

arrrxivvv wrote: ↑25 Feb 2021, 14:30 When turning the ignition to II, all the warning lights turn on.

It does that by design. It is a bulb test.

arrrxivvv · Post by **arrrxivvv** » 01 Mar 2021, 15:21

Thanks for the advice.

Turns out the oil pressor switch has a crack, I didn't see that when I check it. Replaced the switch and the oil pressure light is fixed.

But this does mean that during instrument panel self check at start up, it does check if the sending unit is functioning. Didn't know that.

Post by **SuperHerman** » 01 Mar 2021, 20:28

I am curious if you could run the onboard self diagnostic and find a communication error for a failed oil pressure sensor. To do this unplug the sensor at the harness and run the diagnostic - see if it finds the fault. Wondering how granular the onboard test is. The onboard diagnostic is different than the start up self check.

arrrxivvv · Post by **arrrxivvv** » 01 Mar 2021, 20:39

Good question.

darylrobert · Post by **darylrobert** » 02 Mar 2021, 05:06

ive soldered those little LEDs, its doable but tricky. you will need tweezers and a magnifier glass helps, soldering any longer than a few seconds and the LED will get damaged. i searched online and found what would be suitable size replacements but wasnt sure on the brightness so decided to use recycled LED's from a rearview mirror (fasten seatbelts LED)

Post by **SuperHerman** » 02 Mar 2021, 17:58

darylrobert - clever solution. Did the cannibalized replacement LED match in size, color and brightness?

darylrobert · Post by **darylrobert** » 02 Mar 2021, 18:10

Yes the LEDs are still working well.

Thinking about the posters problem, i am fairly sure that if you unplug the oil pressure electrical connector the light will NOT illuminate, i havent tried this but i think it only iluminates because the engine hasnt started and there is low pressure.

Those oil pressure switches are very simple grounding switch made by a spring and ball bearing and have been used in volvo cars for many years, i took one apart on my 1981 240 and got it working by giving it a good clean,they get gummed up with oil and stop making a ground contact. i would check for a ground signal by connecting a spare wire (bullet connector) you should get a ground before starting and no ground when engine is running.

Does your car have a oil level sensor? i believe only the "R" volvos got the extra oil level sensor and its wired to the same the oil can light.

arrrxivvv · Post by **arrrxivvv** » 02 Mar 2021, 18:16

Indeed when my oil pressure switch was cracked and there's probably not a connection, the oil pressure light does not illuminate when ignition is at II with the engine not running.