Fuel Gauge Enquiry

[shazia]

Hello,

I am a hardware developer working on a project related to fuel monitoring and I am a little confused about a couple of things, it would be really great if someone could help me out with it.

The fuel gauge in vehicles is attached to a sender unit. Between the fuel gauge that consists of a float and the needle you can see on the indicator unit, there is a damping circuit placed somewhere. What this damping unit does is damp the constant vibrations from the float which may come as a result of fuel sloshing. I want information regarding this damping circuit. I need to know the following:

1) Where exactly is this circuit placed?
2) The input voltage of the sender unit is 12V however, the fuel gauge would be damaged if 12V flows through the gauge directly. I have observed that the input on the gauge itself is from around 7V to 12V, there is a resistor placed in between. I want to know the value of this resistor in ohms.
3) There's roughly a 5V potential difference in the gauge, I need to know the current consumption of the fuel gauge.

If anyone can answer these questions, it would be super helpful.
TIA!

 

[anuraagshenoy]

1) Where exactly is this circuit placed?

It is connected to the sender unit programmed with fixed values in the ECU of the car.

2) The input voltage of the sender unit is 12V however, the fuel gauge would be damaged if 12V flows through the gauge directly. I have observed that the input on the gauge itself is from around 7V to 12V, there is a resistor placed in between. I want to know the value of this resistor in ohms.

I am not sure of the voltage variation but I have seen information concerning the different resistance between different 'float' positions in the tank depending on the fuel level. Check the image attached for reference:

3) There's roughly a 5V potential difference in the gauge, I need to know the current consumption of the fuel gauge.

I'll see if I can get any further information on the same.

 

[shazia]

It is connected to the sender unit programmed with fixed values in the ECU of the car.



I am not sure of the voltage variation but I have seen information concerning the different resistance between different 'float' positions in the tank depending on the fuel level. Check the image attached for reference:

View attachment 313226



I'll see if I can get any further information on the same.

Oh this is really helpful!!! Can you please tell me where did you get this table from? I'm actually trying to calibrate the fuel gauge using a microcontroller to give me the fuel level in liters. I'm having trouble with the parameters and ranges. I've been working on this for a good 8-9 months now and this point i'm even running out of useful things to search on the internet. Any help with this would be really appreciated. Thank you so much for your response!

 

[anuraagshenoy]

Oh this is really helpful!!! Can you please tell me where did you get this table from?

I hate visiting authorised service centre for servicing my Creta. Hence got the complete service manual so I can service/fix it myself at my trusted FNG.

The table is from the service manual for my car model: 2017 Hyundai Creta 1.6L CRDi SX (O).