Later DIGITAL Rail Pressure Sensor Scaling

[radz28]

Good day everyone,

After verifying GM doesn't support FUEL RAIL PRESSURE over CANBUS (and therefore HPT can't add it), I'm trying to figure out if there is any information I've missed about how to derive this. I'm working on a 2020 ZL1.

I'm trying to convert/obtain a voltage signal from the 4-wire (the later model) digital rail pressure sensor (a SENT sensor?). I've tapped into the the wire near the ECM (X1 PIN 41 - blue/white), and because (I just learned) it's a digital sensor (as opposed to the older 3-wire), I'm not getting the correct voltage to try to do what I'm trying to do. It doesn't matter if the car's COMMANDING/ACTUAL is 15MPa or 3MPa, it's always reading ~4 volts. I'm not experienced enough to try to use converters or any of that kind of stuff (including creating a harness that could stress or damage the ECM or anything), and was hoping there was a scaler someone's found or used that I might be able to integrate into my set-up. I've tried to see if Holley's got anything or something like that, but I struck out. I'm just trying to import the actual RAIL PRESSURE into my device so I can use it for calculations. Are there other alternatives HPT has that I might be able to use?

Can anyone help?

Thanks,
Chuck

[Camaro6]

You can log rail pressure in hptuners on a 2020 ZL1. I do it all the time and as new as 2023 I've had at the shop.

[radz28]

Yes. But I'm trying to send the rail pressure voltage to another device and I've learned GM doesn't send that voltage via CANBUS, so I'm trying to find a different way of getting it. Do you know of an alternate way to do so?

[blindsquirrel]

Likely the sensor output is PWM and it varies either the duty cycle or frequency in relation to pressure, there is a little processor inside. This is no different than if you were trying to measure voltage coming out of a MAF or flex fuel sensor or cam/crank sensor. All you're getting with a DVOM is an average voltage and nothing about the info contained in the signal's pattern.