2006 Dodge Ram 2500 - While installing a new fuel pump assembly in my truck, i discovered that i have constant voltage on the blue/white fuel sending(gauge) wire. Key on or off, it makes no difference. The ground wire beside it is constant ground also. From schematics i have found, these wires come from the gauge cluster, not the TIPM. The TIPM is new, as that was what caused my fuel pump to fail.My question is, should there be constant voltage to the fuel gauge wire, if not what is telling the cluster to power this wire this wire up. Fuel gauge reads empty with key off and reads correctly with key on, so the gauge is functioning fine. I've had a slow parasitic draw on this truck since i bought it and i believe this very well might be the problem.

 

Looking at the wiring diagrams I have available.... there isn't any detail available on what is happening INSIDE the cluster..... It has several power feeds that are hot at all times, which isn't a surprise.... but, one would think that the fuel gauge would only need to be powered when the ignition was actually on....

Might be interesting to have a look at the Violet/Brown wire on C4, pin 13. Ignition Sense circuit, see if you have voltage there when the ignition is off.

 

Sounds like you could have a failed fuel pump relay. Can you verify if you have a fuel pump relay? If so, how are the blades numbered?

 

No it doesn't have a separate relay, it is in the tipm, which I replaced along with the fuel pump.

 

On the sensor schematic from the tipm supplier my ignition switch is off c1 pin 3. I will check that.