Electrical issue- help please

My oil pressure light has decided it wants to stay on- with the key in or out, I thought it might have been a bad sensor so I replaced that with no improvement. If I disconnect the wire at the sensor the light goes off. It seems especially strange to me that the light will stay on when I pull the key out.

Any thoughts of where I should look next? Ignition switch or instrument panel are my thoughts - but I am not really sure what I should look for or how to test.


BTW-I do have a mechanical gauge as well so I do have oil pressure.

well I looked over the wire in the engine bay, nothing seemed strange, I haven't looked under the dash to closely yet.

Although I do have another symptom that I found on my drive home tonight, my dash lights are not working either.

So I reinspected the engine bay wiring again, and found nothing that appeared to be damaged. I pulled the instrument cluster....and lets just say its a real mess back there, there are at least 2 wires that 'appear' as though they should have been connected to something at some point in time, but no longer are. This is only complicated by the butchering of the wiring done over the years back there by the addition of things like gauges (previous owners) and the stereo, fan and MSD which was done about 10-15 years ago by a family friend.

The only wiring I have done recently is add LED tail lamps with electronic flasher, and a new turn signal switch.

Now here is the current list of things electrically speaking that I have determined are screwed up as of now.

1. Oil light- stays on with ignition off, turn the car on, it gets oil pressure, light goes off, turn the car off it stays off. Turn the ignition back on and it will then stay lit if you pull the key.

2. Dash lights & blower are not working....seem unrelated

3. Horn stopped working

4.Turn signals not blinking correctly- but I have concluded its a bad socket on the passenger side front. I don't believe this should be related to any of the other problems.

The wiring for the turn signal switch was a pretty straightforward replacement, and was buried in the dash so I didn't have to mess with anything else, but I suppose I will go and double check the connection.

I need to get a wiring diagram to help decipher what is what under the dash. anyone have an electronic copy of the diagram?

I am half way to the point that I just want to pull it all out and start fresh and get a new harness designed to handle modern components. But the thought of wiring that much pretty much sickens me.

Tim65GT said:

One side of the oil light gets Ground when the oil press sender unit senses low oil pressure. From what you are describing, this part is working correctly. The other side of the lamp gets 12V only from an ignition source. Somehow, battery power is making it's way to this point.

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That makes me think I could have a bad ignition switch-or at the very least the problem is coming from under the dash.

I have been printing out the various wiring diagrams that I can find online so I can go under the dash to try to decipher what is what.