oil pressure gauge hookup?

[emmotto]

I have a Smiths oil pressure gauge (electric and not connected to anything) and yesterday I discovered that I have something that looks suspiciously like an oil pressure transducer mounted on the spin off filter adapter. There are 2 devices on the adapter - one is my oil pressure idiot light (I know this by my mighty powers of deduction - there are wires going to it and something must be switching the little idiot light on and off) and the other which looks like a rusty little can with 2 spade lugs on top and has no wires going to it.

So I ran a wire direct from one of the prongs to the back of the gauge, and another from the power side of the gauge to the battery. I provided a ground to the case of the gauge. Nothing. Tried swapping the wires. Nothing. Oh - engine WAS RUNNING.

Am I doing this right? Or should there be a ground down at the transducer itself? Are one of the spade lugs for ground and the other for power? Does the gauge work similar to the fuel gauge (hopefully just not as intermittently) where the gauge works off of a variable ground resistance?

Does anyone know how I should be wiring this thing? At least to the point where I can trouble shoot if the gauge or sender are bad?

[TedW]

I suspect that your sender (yes, that is the sender) is pooched. A very common issue (mine was dead when I bought my truck).

You have three options:
1. Live without the gauge
2. Buy a new sender for $100-$150
3. Convert to a Smiths capillary pressure gauge, which operates off of oil pressure directly to the gauge. That's what I did - more reliable (no sender to crash), more accurate (so I have been told) and less expensive. And, it looks authentic. If you care about that sort of thing, which I do.

Just my opinion. Others may have different advice.

Ted

[o2batsea]

It's possible the "idiot light" thing is an oil pressure safety switch. Do you have an electric fuel pump?

Sender may be OK but for a different resistance setting than the Smith's gauge.

All gauges are wired thusly: Keyed or switched 12v+ to the IGN or "+" terminal. From "S" or sender terminal to sender. Sender itself then grounds to engine. Some senders have a "floating" ground, so two prongs; one for wire from gauge the other to ground. There may also be a third terminal for gauge case ground. In addition a lighting device may be present on the gauge so it will be wired from the panel light circuit 12V+ and ground.
All senders are merely devices that offer electrical resistance. The gauge measures how much resistance and the calibrated scale tells you pressure, temperature, etc.