Oil Pressure Guage

[fiatjack]

Hey fellow shade tree mechanics,

Well, my clock works, but its part of the drain on my battery, and the glass is super foggy. Want to change it to an oil pressure gauge. My question is, can i wire it into the same clip the harness that the clock used? Wiring is my nemesis currently, so i'm sure i picked the right car....1979 Spider 2000 carbed. Also, what gauge of wire is the harness in case i need to make repairs in other places.

[18Fiatsandcounting]

You're right, you picked the right car, but this is a do-able modification. You'll need two things:

1. An oil pressure gauge. The bulb wiring for this would be the same as for the clock, in terms of grounding and +12V. The power for the clock is a red/black wire for your model year, but the problem is that this wire is hot all the time (so the clock continues to run with the ignition off). So, you need to look for some yellow/black wires that provide power to the other gauges, and tap into that wire to power the oil pressure gauge.

2. A transducer for the oil pressure. I believe you have an oil pressure idiot light, and the switch for that is mounted in the flange near the oil filter. If you buy a pressure transducer, that might fit into the same hole as the idiot light switch. Might. I'm not positive that the threads/holes are the same. But you can probably get adapters. From the transducer, you would need to run a dedicated wire through the firewall to the sensing terminal of the oil pressure gauge.

Another option is to install a mechanical gauge with its pressure tube running to the port where your oil pressure light was.

Note that in either case, your low oil pressure idiot light won't work any more.

-Bryan

[fiatjack]

Can’t I just splice the idiot light to the same light on the pressure gauge?

[bobplyler]

Can’t I just splice the idiot light to the same light on the pressure gauge?

The idiot light is either on/off. Won't drive the gauge. You need one of these.
https://autoricambi.us/oil-gauge-sending-unit/. A tee fitting would allow keeping the idiot light.

[focodave]

I installed an oil pressure gauge in my '80 about 9 years ago.
Read through this complete thread for details:
https://www.fiatspider.com/f15/viewtopi ... e&start=15
You can retain your idiot light if you install a gauge, simply by using two sending units.
I did not use a "tee" for both sending units.
I installed the two sending units on opposite sides of the casting that the oil filter screws onto (there are two pressure ports on this casting -- one facing the front of the car and one facing the rear of the car).