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Fuel level sensor


434josh
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I am not finding much in the help files but curious what it takes to display fuel level with a 73 ohm empty, 8 ohm full sender. 

I found a call file that I was able to setup and directed an analog input to that cal file but I am not sure if the ecu will read the ohms or only volts. 

Link Extreme G4+

Do I need an external ohms to volts converter or will the ecu read ohms directly? If it will, how is it to be wired? Thanks. 

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Ohms conversion is only relevant if the pull-up resistor is 1000 ohms.  For fuel level you normally have a much lower resistance pull-up than this so the cal table should use volts as the input.    

 

Edit: This post here will give you an idea on how it needs to be wired:

 

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56 minutes ago, Adamw said:

Ohms conversion is only relevant if the pull-up resistor is 1000 ohms.  For fuel level you normally have a much lower resistance pull-up than this so the cal table should use volts as the input.    

 

Edit: This post here will give you an idea on how it needs to be wired:

 

Thanks as usual Adam. 

I am not an electrical wizard but I can certainly duplicate this. Any advice on the specific resistors? The 100 ohm I can get locally are either 1/2 watt or 1/4 watt. Same with the 18k resistor. 

The cap would be 6.3v?

Will all that work? 

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P = V2/R, so 5V2 / 100ohm = 0.25watts.  The 1/4W resistor will get pretty hot with 1/4W going through it, so better go for 1/2W.

18K is going to use almost no power so 1/4W will be fine for that - but 1/2W is perfectly fine too.

Cap rated voltage is not very important but the general rule is to de-rate by about 50%, so if your circuit will see a max of 5V, then you would go for a cap with at least a 10V rating.  

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