As some of you may know I installed a HV/HP pump in the Burb because I was getting a slight lifter tick while idling for any extended length of time. The pump got rid of the ticking but I had "too much" oil pressure according to the ECM.
My first try at a fix was to install the dual remote mount filters and oil cooler and while it did lower the pressure slightly it was not enough to get rid of the check engine light.
I ordered the extension harness above and after a lot of research and some trial and error I figured out the size of the resistor that I needed to make the ECM see the "correct" pressure.
The way the system works is the ECM sends out a ground and a 5V reference signal to the oil pressure sensor. The EOP sensor has a signal wire that goes back to the ECM to tell it how much pressure it is reading. The ECM then sends the data over to the BCM through the serial data line and the BCM sends the signal to the instrument cluster for the gauge.
Basically by adding a resistor to the signal line and adding the white wire to ground the other end of the resistor I created a voltage dividing circuit so the ECM doesn't think there is 70-75 psi but rather 40-45 psi.
Anyway it works and I am stoked about it because I haven't been able to remote start since installing the oil pump because of the CEL.
I used a 300 ohm 5 or 7 watt (not certain) resistor and while the line doesn't see anywhere near that much wattage I over sized the wattage on the resistor so that it runs cooler. With the truck running you can hold the resistor in your hand and it is not even warm.
I forgot to mention... with this set up like I have it the gauge is still fully functional, it is just reading at a different scale I guess is the best way to put it. But its not like just sticking a resistor in to read a certain pressure all the time regardless of pressure. This way if oil pressure goes up OR down it still reads it.