Im looking to up grade the wiring on my 57 D100 project. Looking for a wiring diagram to trouble shoot the fuel gage. Any ideas. My searches have not come with anything useful. Thanks.

The best I can do is a 54 Dodge truck factory service manual.

The wiring on these old Dodge trucks is pretty simple, but I believe that up until 58 or 59 they all had a positive ground. Most people treated them like a negative ground system and it pretty much worked, until it didn't. Then they look at the wiring diagrams and are completely lost.

The head light switch has a circuit breaker on the back end of it. If the lights work, then don't suddenly, and then start working again, it probably means its tripping the breaker. Usually that indicates you have a shorted out wire in the light system.
The power for the headlight circuit breaker comes from the amp meter lead. Through the breaker, it feeds the coil, the stop light switch and the headlight switch. Through the head light switch, power goes to the instrument cluster lights on one (red) wire, a (black) wire to the tail lights, A (yellow) wire to the dimmer switch (The dimmer switch powers the high or low beam headlights) and a (yellow) wire that powers the parking lights. The parking lights are only powered when the head light switch is only 1/2 way pulled out, there is no parking light power when the headlights are turned on. All the lighting grounds through the light mounting hardware, if the ground is bad, you get no, or very poorly lit lights. .

My service manual is in really rough shape and almost 3" thick. I'm not sure I could get a readable scanned picture.

I really sure I wont have a problem with the simple stuff. What is really throwing me off is the fuel gage swstem. It has 3 wire not the usual 2. Any help there would be a great help. Thanks for your help.

So here is my wild a$$ guess, but this is coming from a guy that is using a Dakota tank in his '56 two door dodge wagon that he could never (2 months time) get it to work so went with aftermarket gauge and sender. .

One wire is keyed hot 12 v., one is variable ohms from the sender to the gauge, and one is ground. I think that grounding the sender wire should make the gauge go to full but consider the source. (see above)

I think it's time for you to buy a shop manual with a wiring diagram in it.

Again, from the 54 service manual: m
The fuel gauge system consists of an electro magnetic unit on the instrument panel and a tank unit. the system is connected to the battery through the ignition switch. The gauge operates only when the ignition switch is on.

The electro- magnetic unit on the instrument panel has two magnetic circuits. the two poles of the electro-magnet are equipped with individual windings which produce two distinct magnetic fields.

One of the windings is connected from the switch terminal to a ground. With the ignition switch turned on, the electro-magnet is energized and tends to pull the armature ( to which gauge hand is attached) towars the "empty" gauge position. This winding is called the constant field.

The other winding is connected from the switch to the tank unit and is grounded. This winding is a variable field winding and it pulls the armature towards the "full" gauge position.

The tank unit consists of a float, a float arm, and a variable resister. The tank unit assembly is mounted on a base which is attached to the tank. It is held in place by a retainer and a rubber seal. A single wire connects the electro-magnet and the tank unit. The tank unit is grounded.
Your 3 wires are a ground wire. a power wire from the switch (connected to both armatures), (marked SW) and a variable field wire (marked GA)

Another note: As the fuel in the tank moves from "full" to "empty", a change in the magnetic field surrounding the variable field magnet takes place. Then the gauge hand moves indicating the amount of fuel in the tank.

When the fuel tank is empty, the float has dropped to the bottom of the tank. Downward motion of the float moves the variable resister contact finger and increases the amount of resistance in the variable field circuit. The increased resistance decreases the current flow and the magnetic pull of the variable field magnet.

The decreased magnetic pull of the variable field magnet allows the constant field magnet to move the gauge hand to the "empty" position..
When fuel is added to the tank, the float is lifted. This moves the variable resistance contact finger, decreasing the resistance in the variable field circuit.

This decrease in resistance allows more current to flow in the variable field circuit, increases the magnetic pull of its magnet and pulls the gauge hand towards the "full" position.

Hopefully you can figure out how to test the wires to be sure they are good. You also want to be sure the sending unit in the tank is good. With the float out of the tank, you should see a change in resistance as the float arm is moved up and down. The bood does not give resistance numbers. The test is how bright a 6 volt buld in a test light is as the arm moves. Remember, there is less sresistance as the float arm is lifted.

I don't know about the truck side, but the pass car side quit using that style fuel gauge long before 1954. But here's the section about that style gauge

Well thank you guys for all the replys. I will let you know if im able to get it wirking...Thanks again.