Cannot read external sensor properly. HELP!

Using Arduino General Electronics
#1

So i have my gizmo setup. Arduino nano. I am using it on a car. When i test it, i can read external sensors fine. 0-5V no issue.

My friend on the other hand, can only see 0.15V coming in out of an expected 2.5v.

When he connects volt meter it reads 2.5v, his sensor is displaying the correct value for 2.5V scaling/multiplier

When I test using a wire from 5V on the nano to the header input pin for the sensor, it reads entire 5V.
(i'm using actual Vcc reference using code)

We made sure to use the same grounding locations for both devices.
The car is on, but the engine isn't running during these tests (ignition on)

IS there anything that could cause this behavior that I'm missing?

#2

You missed showing your sketch and a schematic of the project.

#3 
int sensor=A5;

void setup() {
  // put your setup code here, to run once:
pinMode(sensor,INPUT)
}

void loop() {
  // put your main code here, to run repeatedly:

int _read = analogRead(sensor);
 float voltage = _read * (5.0 / 1023.0);
   
  Serial.println(voltage);
  
 
}

842×571 3.94 KB

#4

The A/D functions best with a 10K shunt input resistor.

Let’s see what the output circuit of the sensor looks like.

BTW, pinMode(sensor,INPUT) is not needed, besides you are missing the ending ;

#5

That I do not have. It's an Innovate LC1 AFR sensor.

#6

Do you have a PDF file of the manual.

#7

Here it is larry

I should add that the other controllers have been AEM controllers, this is the first innovate.

#8

Assume you are using the sensor analog 2 output.

Try placing a 10K from A5 to GND.

Also a small filter capacitor across the sensor output to GND might be a good idea, .1µf

You do have the Arduino GND connected to the GND at the sensor.

When the sensor output voltage reads X volts, do you measure X volts across the shunt 10K resistor, use a DVM?

#9

Hi,
I assume you are talking about 2 motor vehicles, yours works fine, but your friend's does not.

Make sure your friend has the gnd of the Arduino connected to gnd or the car.

Is your friend's car the same make and model as yours?
Does it have the same oxygen AFR sensor?

Tom... :slight_smile:

#10

TomGeorge:
Hi,
I assume you are talking about 2 motor vehicles, yours works fine, but your friend's does not.

Make sure your friend has the gnd of the Arduino connected to gnd or the car.

Is your friend's car the same make and model as yours?
Does it have the same oxygen AFR sensor?

Tom... :slight_smile:

Different model AFR controller. Grounds are the same exact spot.

larryd:
Assume you are using the sensor analog 2 output.

Try placing a 10K from A5 to GND.

Also a small filter capacitor across the sensor output to GND might be a good idea, .1µf

You do have the Arduino GND connected to the GND at the sensor.

When the sensor output voltage reads X volts, do you measure X volts across the shunt 10K resistor, use a DVM?

there is a .22uf there, same result. DVM shows 5v on the AFR controller by itself but when those wires are fed into arduino only 1.x volts come across.

A mystery i tell you.

#11

Hi,
Have you swapped yours and the other projects over to see if the fault follows the project?

The LC-1 is the unit you are having problems with, is it?

Where are you connecting the Nano to get the voltage reading?
Have you programmed the LC-1 for proper analog output scaling?
sensor1.jpg

Tom… :slight_smile:

#12

Hi,
With the projects disconnected from the AFR controller and power OFF.

With a DMM measure the resistance between X1-5 and X1-6 on the project.
That is measure to see what resistance/load the project is applying to the AFR controller.

See if they are the same readings.

Tom... :slight_smile:

#13

Hey tom, he's a far way from me, everyone else that is testing this has it working. For now I'll have to pass it over i doubt the error is on my side.

My only concern is that the impedance somewhere may be too high. But i'm not confident.

Thanks for your help guys

#14