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ok i got the majority of my wiring issues figure out what im wondering is i hook what the book shows as the oil psi sending wire to the positive and nothing happens, i hook it to the negative and the guage works. isnt this opposite of what is really supposed to happen? this is on a 91 f350 of what was a 7.3l
No. The dash gauge is connected to + voltage (reduced) and the sender is grounded to the block. If there is oil pressure present, the sender completes the circuit to ground to allow some current through the gauge to move the needle.
The oil pressure gauge system in these trucks is really just a glorified idiot light. They are really not that accurate.
I think 1987 was the change over year for the idiot gauge in the F series trucks. Rangers before that already had them even in the mid 80s.
My gauge does read dynamic depending on operating conditions but with no numbers, its still more or less meaningless. There is a way to convert later gauges to dynamic readout but I don't remember all of the details.
I agree that a good quality mechanical gauge is a better choice if you are serious about monitoring oil pressure.
Hey David. I went back to work last April (after being laid off for 5 months) and have been working steady since. My commute is 150 miles a day, so I haven't had much time to spend on the computer.