I can not find any wiring diagram that shows the correct fuel module connector (7 pin). Gage stays pegged beyond full, and fuel low light will not illuminate, even when usable fuel in tank is exhausted. Probably, the problem is inside tank, but I would like to know what the wiring is so I can meter out the harness/connector. Sounds to me like an open circuit... Bob

Here ya go.

The gauge is faulty or the sending unit in the fuel tank is bad ! There is away to test it, find a wiring diagram an locate the two wires at the fuel pump sending unit connector . Go to radio shack or some other electronics store an buy some resistors of differing resistance , I'm not sure of resistor sizes , I will look it up on my ford service info system. If you jump the right resisters into the fuel sending unit circuit you can make the gauge show 1/4 - 1/2 - 3/4 an full. If it move to those positions with the right size resistors it's not the gauge but the sending unit in the gas tank ! Diagnosis of Stuck Fuel Gauge Is it Gauge or Sending Unit

look at wiring on top of fuel tank at the connection- either ground rotted off or bare wires touching or a crushed connector

according to wiring diagram no module . do you have pwr at trailor connector. should be green w/ white wire coming into trailor connector. ( I believe pin 7 on connector ground should be pin 5 and is white with black wire )

Most of the time the gauge unit in the tank goes bad but turning the key on and off won't make any difference. Near the tank there is a multi wire electrical connector, With it unplugged and the key on probing the wires to the front of the truck with a test light one of the wires will light in a slow blinking, This is the gas gauge. with the light blinking the gauge should read something. un plugged should read empty and cross the light to ground it should read full. If the light doesnt come on your on the way back to the dash the wire could be in troble anywhere. repairs for other things are ussally the cause. If the test light check worked then the sending unit in the tank is bad and it will need to be replaced. Repairing them doesn't seem to stay fixed. A gas theif may have run into it with a hose and they can't take much banging around. The fuel gage and fuses are next. The temperture gauge works on the same power if it works OK the power is good. Then its the gage or the wire the is a voltage limiter card in a slot next to the gage in the cluster . The dealer can order a new one when you call them with the VIN and tell them you want the fuel gauge limiter module. If you have the skills to remove the cluster and see the module 1 in. X 2 in. flat electrical card. It has a part # on it and the dealer can verify that your looking at the right part. the gages seldom fail unless their submerised in water. Har driving can sometines loosen the connections to the cluster and redoing them and turning it on again, may correct thr problem. do this with the card and the gage too before you but anything, check the wire from the gage module maks it all the way to the gas tank with a jumper wire and a test light as the wire being broken somethere is most common.

located the temp sending unit check that its pluged in, if it is unplug it and ground the wire to something metal (with the switch on) and see if the gauge moves if it does then your temp sending unit is bad and needs replaced

It is either the sending unit in the gas tank or the dashboard gauge, either job poses its own challenges take your pick. If it is the gauge if you were lucky in a couple of weeks it will become unstuck in to pegged out position but that is only if it is a mechanical issue with the needle itself wedged in place.

I just had a similar issue with my 1995 Buick century. My issue started out with the gage being almost pegged with the car off. When I turned the key to run it pegged the gage completely. I first called AutoZone and they told me it was either the temperature sensor, thermostat, or gage.
I knew that my thermostat wasn’t bad because I replaced it a while back. I then checked my sensor; I unhooked the two pin connector of this sensor at the block and suspected the needle to drop to zero. This was not the case.
I then checked my wires using a multimeter to verify that there was no short at my firewall. My wiring was fine.
I then called a family mechanic and he instructed me that there is also a "temperature switch" that also is interconnected to the coolant temperature gage. I then found this switch which was threaded into the block near the firewall of my car. I unhooked the 2 pin connector and suspected that the gage would return to the neutral position. And sure enough it did!!
This could have been a heck of a lot easier if AutoZone could have told me that my car has a "temperature switch". But non the less it was only a $15 fix!

First try unhooking your sensors and switch to see if this is the problem, I would lastly suspect your gage to fail!

Good Luck

Jason, as far as the fuel gage, try a couple of resisters at the wiring for fuel gage sending unit, in gas tank. It's two wires, use the resister inline between the two wires. One resister is for low fuel level, the other for high fuel, If the gage reacts properly to both resisters, the problem is the sending unit in the gas tank. You can try 40 ohm and 250 ohm resistors. I used to get resistors from radio shack, I don't know if they went bankrupt? The store in my community closed. Other places may have resisters?
Just to add, the wire colors for sending unit/sensor are purple and black with white tracer.

The easiest way to test this at home is to find the 4 wire connector back at the fuel tank. (Find the violet/white wire and the orange/yellow.) Unplug the connector and attach a resistor between these wires, turn the key on and check. You will need a 145 ohm resistor for full and 22 ohm resistor for empty.Doing this checks the guage,wires and slosh module in the dash.If the gauge reads correctly, your problem is in the tank. You can pick the resistors up at Radio Shack or any electronics store. Or you can try and rent a guage tester from your local parts house. Good Luck, let me know if you need anything else.