Grid heater light.

[bigyeep]

I am looking at a 2007 dually with the 5.9 in it. The owner stated that he thinks the fuel pump is going out. The reason he stated that is because when the fuel tank gets down to 1/4 tank the grid heater light comes on. I have owned several diesels and never herd of this. Any help with why the grid heater light would be coming on would be helpful.

 

[Dennis Shellito]

I have never seen this before either. You should see what the volt reading is when the GHL is on with the truck idling. If the voltage is under 11 volts the heater is turned on. I agree with the owner that it is probably getting some weird feed back from the fuel tank pump/level sensor. It could be a bad ground in that circuit.