Oil pressure guage calibration

[Bitsyncmaster]

I had a request from an owner to relate the resistance (from the oil sender) to each mark on the gauge.

76 ohms = 80 PSI - 162 ma.
63 ohms = 3/4 mark - 173 ma.
43 ohms = 1/2 mark - 191 ma.
26 ohms = 1/4 mark - 219 ma.
0 ohms = 0 PSI - 321 ma.

Note the current shown is the power on the gauge (14.0 volts). So I suspect the current sinking in the sender is 1/2 that current.

[dmcnc]

Would something like this work?

https://www.finditparts.com/products...iABEgKFpPD_BwE

Datcon Instruments Scale Range: 0-80 PSI/0-5 Bar Resistance: 0-90 Ohms Lighted

[Josh]

This is very helpful dave! Thank you for this.

On my swaps I use a combo sender/light unit to ensure everything on the dash works properly.
I "calibrate" it with a 300 ohm resistor in parallel but it is a compromise.

https://www.summitracing.com/int/parts/vdo-360025

[Bitsyncmaster]

Would something like this work?

https://www.finditparts.com/products...iABEgKFpPD_BwE

Datcon Instruments Scale Range: 0-80 PSI/0-5 Bar Resistance: 0-90 Ohms Lighted

That would probably work but I would guess the gauge would read higher since our 80 PSI requires 76 ohms and this sender would be 90 ohms at 80 PSI.

This was from an owner that wanted to drive the gauge with his EFI ECU. For that and most of these old gauges you would just drive a MOSFET with a PWM (pulse width modulation) that sinks the gauge into to ground. So he would use any sender and read the voltage and convert that to a PWM. That is what I did with my fuel gauge ECU.