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Dave Nova
Dave Nova, Cadillac Technician
Category: Cadillac
Satisfied Customers: 19452
Experience:  ASE Master Certification. GM World Class Certification
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1999 Cadillac deville: repair shop..oil pressure..sending unit..gauge

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Hi, I own a auto repair shop here in Ohio, I just changed a engine in a 1999 Cadillac deville and now it says stop engine, oil pressure low. I changed the sending unit, still says the same thing. I put a gauge on it and at idle it is 70 to 80 pounds. I cannot find anything wrong with the wiring, any ideas? Thanks Dale
Hello and thank you for using JustAnswer. My name is XXXXX XXXXX I will do my best to help you with your Cadillac problem.

Try disconnecting the engine oil level sensor connector and see if the light goes out. The sensor is located in the oil pan, near the compressor. Let me know what this does.

Customer: replied 5 years ago.
I am very aware where the sensor is, I am a northstar exspert, I forgot to mention that I did unplug the light, I also ran a ground wire over to the black wire, ground, on the plug, the light would go out for about 30 seconds and come back on. We removed the engine and drilled the head bolts out and installed timeserts, we have repaired over 400 of these cars, but I cannot figure out the deal on this. Thanks Dale
Does your scan tool data show the same oil pressure reading that the manual gauge displayed?
Customer: replied 5 years ago.
Ok, you go me there, I did not check that, but again, even if I do check with a scan tool it is going to tell me what the instument panel tells me because the ecm is displaying the info it has on the dash right, I know for a fact it has great oil pressure, just dont know why it is displaying this warning. i am not at the shop but I can check that tomorrow if you need me to.
Yes, that would be the next step. The oil pressure sensor feeds info to the PCM, then the PCM sends a class 2 data signal to the instrument panel. By verifying the pressure reading in the PCM data we can find out whether the problem is between the sensor and the PCM or if the problem is instead in the instrument cluster. Please let me know when you find out and we can take it from there.
Customer: replied 5 years ago.
ok, I will check in the morning, however, the light was not on when the car came in a few days ago. Thanks
The problem may be a cut in the wire coming from the sending unit. If the PCM display does not coincide with the manual gauge reading then the Tan/Black wire between the sensor and the PCM will need to be checked for continuity.
Customer: replied 5 years ago.
I did check the wire as far as I could, do you have the wire diagram for the sending unit?
Sure here is the diagram and connector end view.


Customer: replied 5 years ago.
Ok, well i am done with this. I told him to take the car to the dealer and let them fix it and I would pick up the tab. You really havnt told me anything I dont already know, do i still need to pay you the full amount? i could of got the diagram that you sent through my aldata account. I will pay you however. Let me know. I realize that this is probally something you would need to be hands on with to repair, we tryed right. It is so simple, a signal going to the pcm and a ground, simple as that, but i have failed to locate the problem and I never fail. Thanks Dale
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