Depends//
The factory sender value is 40 ohms empty and 250 ohms full. You can try tapping the gauge wire into connector 2 pin 54 at the PCM and see if the gauge functions at all.

If not you can then try cutting the above wire to the pcm and tie directly into the gas gauge and see if it will work.

But/ the gas gauge you purchased has to function in the above ohm level range in order to work at all or be any where near accurate.

If you have to cut the wire to the pcm it will set a code and will not run any evap related tests due to lack of a correct fuel level input.

 

I could be full of **** but I swear when I did this a few years ago in my old monte carlo with a LS conversion that autometer had a gauge available that could learn the full and empty ohm readings allowing it to work on a variety of vehicles.

 

Thank you very much. Just to make sure I have my info straight, didn't GM actually reverse the ohms after 2004? My truck would be 250 empty and 40 full?

 

Another question...

Any of those wires in that connector that I could tap into to make an SES light come on?

 

brown with white trace at oem cluster connector.

 

You can turn the fuel gauge output on in the calibration and the PCM will drive the Fuel Gauge

 

How would I do this? Right now I am adjusting F0501 table and it does nothing. I don't see a way to "turn the fuel gauge output on" in EFI live, (Cos5 on a 99 Silverado 1500).

Trying to get an aftermarket sender to work on this truck, it functions but the scale is way off... Full tank=3/4 on gauge etc.

 

Hate to bring this thread back from the dead, but does anyone have access to any GM cluster schematics? And I'm not talking about the wiring diagram. I'm talking about board level schematics.