Mpvi3 and Aem 30-0334 troubleshooting

[BlackhawkLSX]

Mpv3, pro link, and aem 0334 wideband.
The wide band is working, but hp tuners isn't registering any data from the wb. After alot of reading and trying, I got it to work once for half a second, it froze, and hasnt worked since. Has anyone ever checked the voltage coming out of the guage? Positive and negative both show 2-5 volts or so and both fluctuate when given gas. i read the negative was just a reference voltage, so shouldnt it stay the same at all times? Has anyone with this problem found a solution? Is it in the vcm or the wideband?

[gtstorey]

Voltage from the gauge should vary in proportion to the AFR. Negative output from the gauge is a ground. How are you measuring voltage on the “negative”?

[BlackhawkLSX]

Analog Positive and analog negative wires both show to be 0-5v. Not talking about the ground wire for the guage itself. I'm using a multimeter, grounding the negative to the frame and just putting the positive on each wire individually to see which one isn't working. Seems they both do. Now I'm questioning the serial connection to the mpvi3 or a setting in the program

[gtstorey]

Just to be clear you are getting voltage on the white and brown wires to a negative frame ground? To check the analog voltage you should just check between the two wires. But voltage to ground on the negative doesn’t sound right. If using something like the ac pressure sensor to capture the voltage, you would typically tie the negative to the “low reference” aka ECM ground. Having voltage there would give everything else that uses that ground fits.

[BlackhawkLSX]

Yes. There is voltage on the brown wire. To my understanding, it isn't a ground. It's a negative used as a reference voltage, and the difference in the 2 wires is whats being measured. Maybe I'm misunderstanding. Regardless, there's a fluctuating voltage on both analog wires. There's also a voltage fluctuation when I check between the two wires. So it seems to me to be working.

[gtstorey]

Never heard that it’s a reference voltage on the analog negative. Don’t confuse low reference which it ties to on some GM vehicles with a reference voltage.

Video the gauge reading with the voltmeter readings and see if they match after you do the math.

[BlackhawkLSX]

I went back and tried to match any of the voltages to the afr, and nothing lined up, so I checked the main chassis ground. It's reading 0v with the gauge unplugged, and .04v with it plugged in. I'm guessing there's a problem in the gauge

[gtstorey]

Not sure how/what you are checking on chassis ground but 0.04 volts isn’t much. Means your ground could be better but it’s not real bad. That’s why the analog ground is typical used when feeding through the ecm.

[BlackhawkLSX]

Never heard that it’s a reference voltage on the analog negative. Don’t confuse low reference which it ties to on some GM vehicles with a reference voltage.

Video the gauge reading with the voltmeter readings and see if they match after you do the math.

First video is the positive and negative. Green being positive.
Second is them together. Sorry for the crappy quality, I didn't have anywhere to place my phone. Leads on the meter are too short
https://youtube.com/shorts/Lqo-KFBWjSs?feature=shared
https://youtube.com/shorts/4QHiJwxRaR4?feature=shared

[BlackhawkLSX]

Well, I added a ground wire to the analog negative connection and all is well. They should really add that into the directions instead of making it seem so straight forward as to just connect the 2 wires to the 2 wires on the pro link..