Digital Dash Fake Oil Pressure Gauge - Sabotaged by Ford October 13, 2017, 02:58:41 PM I think I figured out an additional reason why Ford made the oil pressure gauge "fake". It seems that between the tolerances of even the fat sender and the dashboard that there was no winning. Look at tolerances of a typical Wells oil pressure PS4 sender here -> http://www.wellsve.com/showall_ds_oil.php 0-4 PSI - Open Ckt4-8 PSI - 24-36 Ohms90 PSI - 8.5-17.5 OhmsAll over the place. Oh, and you can now see the reason why they call it a sender and a switch, because it becomes open circuit below 4 PSI. Now look at what I got for readings when I put a decade box between the sensor wire and ground. It's almost as if the gauge wants to see something between a real sender like the Autometer 2241 and the OEM switch/sender. Here are some numbers and graphs to confuse you:Bottom line, using the fat sender, mine reads off-scale high due to the sender reading low by 5 ohms (I used air pressure @ ~58 psi and saw 15 ohms, yet it should read ~20 ohms looking at the plot. EXCEPT that if you look at the range of acceptable values for a typical sender unit (PS4), it's probably barely within tolerance :/If I add a 10 ohm resistor in series with my sender, it reads "O" cold and falls to "R" when warm. Of course if you note in my pic above, the gauge has 5 readings, 1 bar is open circuit (less than 4 PSI)4 bars is the next level, also known as "R" - this covers all pressures between 4-54 psi (my estimate)5 bars is "O" 55-79 psi is my estimate6 bars is "N" or >80 psi (my guess)"8 bars" is an error condition where it sees pressure that's "too high" (<6 ohms) It displays as the 2 highest bars and 2 lowest barsIt's possible I'm off in my estimated range of pressure of each bar, and it follows the nominal gauge output, or maybe the lower tolerance, but it matters not since there's very little to be learned from a gauge that can't read below ~40 psi. Unlike the speedo 85MPH limit fix, it's unlikely that the shared bar gauge could be made to read properly without reprogramming a PROM in there. If anybody has any electrical diagrams of the speedo, or any idea how to fix this problem, I'd love to see it. The tolerances are so loose, I wouldn't even dare to recommend a sender and resistance to add in series to get it to use the 3 available bars intelligently. I am considering getting the Autometer 2241 and trying to work with that as it must have a better tolerance than the cheesy OEM "sender/switches"