Oil pressure gauge faulty?
#1
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Oil pressure gauge faulty?
Had the car in the last couple of days to have the a/c comrpessor r/r'd. Took the car out this afternoon in 35C heat and the a/c was colder than I have ever experienced at such ambient. I then noticed that the oil pressure readout on the dash was a full scale. when the engine is switched off it zeroes.
To me this suggests a problem with the sender unit or it is reading correctly and something wrong with the pressure relief valve. I suspect the former although must say I felt uncomfortable not having the analogue gauge behaving as normal. I have noted earlier that the pressure gauge needle could sometimes be a little unstable just above tickover.
Do these symptoms sound familiar to anyone?
Regards
Fred
To me this suggests a problem with the sender unit or it is reading correctly and something wrong with the pressure relief valve. I suspect the former although must say I felt uncomfortable not having the analogue gauge behaving as normal. I have noted earlier that the pressure gauge needle could sometimes be a little unstable just above tickover.
Do these symptoms sound familiar to anyone?
Regards
Fred
#3
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Have not checked anything as yet- no logical reason I can think of why any wires on the oil pressure sensor should have been disturbed yet alone re-installed wrong way round- interesting thought.
Regards
Fred
Regards
Fred
#5
Fred, if the a/c wires have been messed around near the compressor, then this could have moved the front harness.
The oil pressure wires run through this harness and having just dissected a s4 harness which has been out here for the last 10 years there is a good chance the wire jackets within the sleeving have crumbled and there may be a short. If there is any damage to the ends of the front harness then there is a good chance that the center of the harness where the wires double back on themselves is shot.
Just a thought and can be checked by checking the resistance between the oil sender plug and the 14 pin connector.
The oil pressure wires run through this harness and having just dissected a s4 harness which has been out here for the last 10 years there is a good chance the wire jackets within the sleeving have crumbled and there may be a short. If there is any damage to the ends of the front harness then there is a good chance that the center of the harness where the wires double back on themselves is shot.
Just a thought and can be checked by checking the resistance between the oil sender plug and the 14 pin connector.
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Rexxus (08-26-2021)
#7
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Thread Starter
Fred, if the a/c wires have been messed around near the compressor, then this could have moved the front harness.
The oil pressure wires run through this harness and having just dissected a s4 harness which has been out here for the last 10 years there is a good chance the wire jackets within the sleeving have crumbled and there may be a short. If there is any damage to the ends of the front harness then there is a good chance that the center of the harness where the wires double back on themselves is shot.
Just a thought and can be checked by checking the resistance between the oil sender plug and the 14 pin connector.
The oil pressure wires run through this harness and having just dissected a s4 harness which has been out here for the last 10 years there is a good chance the wire jackets within the sleeving have crumbled and there may be a short. If there is any damage to the ends of the front harness then there is a good chance that the center of the harness where the wires double back on themselves is shot.
Just a thought and can be checked by checking the resistance between the oil sender plug and the 14 pin connector.
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#8
To be fair I am not sure if open is max or not, however there are two oil connectors, at least on my 90. There is a single wire which goes to the oil level sender, then three wires which go to the oil pressure sender. I have no idea what the effect of the failure of one of these three wires would be, someone wiser than me would need to answer that.
#12
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It could be anything that breaks the electrical path, but the sender is the most likely culprit if it is still connected. The sender provides a variable resistance signal over a fairly small range, higher for higher oil pressure, so if it fails open circuit, that pegs the gauge.
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GUMBALL (12-19-2021)
#13
What about this?
Hiya,
I have the same issue. Oil gauge reads full scale all the time. BUT, I disconnected the negative terminal on the battery and noticed the gauge went to zero. Does that mean anything to anyone?
I have the same issue. Oil gauge reads full scale all the time. BUT, I disconnected the negative terminal on the battery and noticed the gauge went to zero. Does that mean anything to anyone?
#14
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Never managed to fathom out why the three pin sender seemingly had the problems it exhibited. In your case I would check the state of the wiring first by taking a look at the 14 pin connector next to the hot post and the state of the wires as they enter the sender next to the oil filter.
You did not say what model year you have.
Last edited by FredR; 12-17-2021 at 02:47 AM.
#15
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Fred, when I rewired the whole front of an 86 32V, I was surprised to see the oil pressure sender worked backwards to most others. That is to say, open circuit from the sender gave full scale deflection, closed circuit [grounded] gave '0' deflection.
Your GTS will have a 3 wire sender though and I don't know if they work the same?
Your GTS will have a 3 wire sender though and I don't know if they work the same?