Connecting Teltonika GPS Tracker to Vehicle Fuel Gauge Sensor (Part I)

This video focuses on Hardware interfacing aspect for Software or Application interfacing see Part II.
For Part II :    • Connect Teltonika GPS Tracker to Vehi...  

Note: Sorry for some duplicated segments while merging the video,

In this video, I will gone a describe
1. The working of Vehicle Fuel gauge
a. Sending Unit in fuel tank
b. Display on cluster panel
2. How to Connect Teltonika GPS tracker with fuel gauge
Currently some Teltonika devices support the Bluetooth OBD2 connection but not all vehicles are OBD2 compliant and even if they do not support fuel Level sensor, But many Teltonika devices supports the Analog Input, and send analog data of voltage ranges between 0 - 15 v.
Now we need to connect Fuel Level output from Vehicle to the Analog input of the Teltonika Devices but only after proper identification of both.
The Teltonika Device model have is FMB122, along with the harness, and the wiring diagram is displayed on its back, as you can see the Red wire is +Vcc, Black is -ve Ground, Yellow is or ignition input,
FMB122 model supports 2 Analog inputs, AIN1 or gray wire Or AIN2 the white wire. Other models may have different color coding or wire Number so do it accordingly.
Vehicle fuel gauge works pretty much the same like a Potentiometer or voltage divider.
There is a Fixed resistance in the Fuel gauge, (mostly around 110 Ohm), and variable resistance inside the Fuel tank along with the fuel pump, that varies between 4 -110 Ohm, and both the resistances are connected in series as you can see
When the fuel tank is empty the Input volts will be equally divided among both of the resistances, as both Ohms will be equal as well

When the fuel tank is full, variable resistance (Sending Unit) will be the lowest (4 Ohm) and therefore the voltage drop across the variable resistor will also be the lowest around 700 MV.
If the fuel tank connector wire connector is disconnected, there will be no voltage drop across the Sending Unit (or VR) and we will get full input volts.
This will also help us out during various diagnostics.
With the Ignition On, Use multimeter to find +ve Wire of the Fuel gauge Connector, in my case it was the Center wire No. 2