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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » Reading sensor voltage

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Author	Topic: Reading sensor voltage

captainmack

Member
Posts: 3

Reading sensor voltage
on: January 17, 2021 (GMT)

Hello, I was wondering if anyone knows if there’s a way to directly read the output voltage of specific sensors using TorquePro. Particularly the MAF sensor. I’m troubleshooting an issue and my workshop manual tells me what voltage the sensor is supposed to output, but not the actual grams/second value (which is all I can find in the app). I’m just hoping there’s a way to read voltage without having to jerry rig and tap into the sensor with a voltmeter. Thanks for any info!

moreause

Member
Posts: 643

Re: Reading sensor voltage
on: January 17, 2021 (GMT)

i would say NO

if you have the manual you probably do a guess of the value

it’s a simple math equation most of the time

X volts = Y flow

Capp777

Member
Posts: 2994

Re: Reading sensor voltage
on: January 17, 2021 (GMT)

It might be useful if you provided vehicle
information.

Your ECU is converting the voltage to g/s so
for giggles you could revert it back to see if
it matches your manual…

[10]*(1/131)

Val{Mass Air Flow Rate}*(1/131)

Pid: 0110

Assumes:

0 g/s = 0 volts

655 g/s = 5 volts

captainmack

Member
Posts: 3

Re: Reading sensor voltage
on: January 17, 2021 (GMT)

Yeah I figure it’s a simple linear equation, y = mx + b, just not sure what the m is. I have a 2011 Mazda 6 that’s been throwing a P0101 code, which is the MAF sensor out of range. I’ve replaced the filter and sensor and can’t find any intake leaks but it keeps getting thrown. Right now I’m trying to confirm if the replacement sensor is good. The workshop manual says the sensor should output .68V with the engine off and 1.2V at idle, but doesn’t convert those to the g/s values which is all I can read with TorquePro. I might just have to disconnect the sensor, jumper 12 volts to it, and read the output with a voltmeter.

moreause

Member
Posts: 643

Re: Reading sensor voltage
on: January 17, 2021 (GMT)

12v ??

just saying most sensor are 5V

just jerry rig some extension jumper and measur the voltage

with the sensor in the car

or ask you mother for needle or something similare to back probe the connector

ps most sensor range are from 0.5 to 4.5 V

if you get out if this range it bad ground it will go up to 5
and if you have a bad 5V it will go to 0
so the car can detect faulty wiring this way

captainmack

Member
Posts: 3

Re: Reading sensor voltage
on: January 17, 2021 (GMT)

Thanks for the advice! Yeah I’ll see what I can do.
Yeah it’s definitely 12V for this one, the manual has wiring diagrams and I’ve measured the input voltage at the connector before to make sure it was getting power and it was showing 12.

Capp777

Member
Posts: 2994

Re: Reading sensor voltage
on: January 17, 2021 (GMT)

You might try Forscan app.

My manual reading suggests a typical MAF sensor
uses…

12V feed wire,

5V reference wire from the PCM,

Signal wire back to the PCM,

Ground wire.

Vehicle wiring diagram should be used.

Typical signal voltage of 1.5V to 2.5V at
idle which increases smoothly in a linear
fashion to wide open throttle.

—–

y = mx + b

m is the slope/span.
b is the intercept/zero.

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