Getting 2.5 volts at fuel/sending unit....how come?

[guimond47]

Hey guys i just decided to test how much voltage is coming from the PCM to the sending unit since my gas gauge always says over full on my grand prix 1997 gtp and im reading 2.5 volts with the key on when its saposse to be 12 volts. i figuered out this may be my problem.... but i cant figuer out what device throws the voltage out to the sending unit so i can replace it to fix my issue. anyone know?
would be greatly helpful.

 

[TheOtherNick]

gpona.com has a gm service manual with all the wiring diagrams for your car.

 

[guimond47]

no wiring diagram in those service manuals... i checked. unless u can find it for me . thanks 97 gp gtp

 

[kevins]

I think that is a 5volt circuit

 

[kevins]

9 out of 10 times the level sensor is causing an open circuit. 88 ohms or higher will read a full tank. The float contacts wear causing an open with infinite resistance.

 

[kevins]

take the purple wire at the tank and jump it to the black with white wire and the gauge should drop to empty.

 

[guimond47]

Did it and it dint drop to empty stayed up. Even wen the sending unit itself is unpluged it still stays up... Very confusing. Wish there was a wiring diagram on this...

 

[guimond47]

And the fuel sender inside the tank says 43 ohms which is like half tank! Soo theres something not rite

 

[kevins]

And the fuel sender inside the tank says 43 ohms which is like half tank! Soo theres something not rite

fuel

 

[kevins]

send me your email and ill send u the diagram.

 

[kevins]

You should have roughly 4.8 volts at purple wire (unplugged and key on)