Testing Oil Pressure Sending Unit?
08-04-2011, 02:48 PM
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Testing Oil Pressure Sending Unit?
How do I check if the sending unit is working correctly? I just had a new one installed, but it does not jibe with the readings from a mechanical pressure gauge.
I read somewhere that, if the unit is bad, the pressure gauge will shoot to 5 bars when the ignition is on (but before starting the engine). Can anyone verify this?
TIA for your help,
Phil
I read somewhere that, if the unit is bad, the pressure gauge will shoot to 5 bars when the ignition is on (but before starting the engine). Can anyone verify this?
TIA for your help,
Phil
08-04-2011, 03:25 PM
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Pressure senders are simple inside. They have a variable resister. The resistance drops as the pressure goes up. When I bought my coupe, someone had hooked up the pressure sender backwards. The oil pressure gauge would peg as soon as you turned on the ignition. After some troubleshooting, I discovered the wires were reversed. I swapped them and the oil pressure and oil light began working properly.
08-05-2011, 04:09 PM
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Pressure senders are simple inside. They have a variable resister. The resistance drops as the pressure goes up. When I bought my coupe, someone had hooked up the pressure sender backwards. The oil pressure gauge would peg as soon as you turned on the ignition. After some troubleshooting, I discovered the wires were reversed. I swapped them and the oil pressure and oil light began working properly.
An aftermarket replacement I bought did the same thing. The distributor and manufacturer replaced it for free, but the replacement did the same thing. I found that the manufacturer had reversed the small and large spade connectors from what is standard for our cars (the manufacturer did this because the opposite orientation works on some other models that this sender fits). Upon close inspection, the terminals were labeled on the bright plated cup shaped enclosure, but you really have to look for them and compare to the original. I suggested that to the mf'g. that they include a notice in the box alerting future customers to this anomaly, but who knows if they decided to do that.
Last edited by altarchsa; 08-07-2011 at 12:14 AM.
