Hot Rods 55 dodge Sending Unit Question

Hi! Thanks for stopping in to help me!

I have a 55 dodge sierra wagon.
I just rewired the whole car with a new harness. I went from 6v to 12v.

The last wire I have to hook up as for my sending unit I'm not sure if it's my gas gauge itself that is not functioning or if it's the sending unit....I'm not sure how to test it to see which one isn't working?

If I locate a new sending unit does it have to be 6V or 12v? I've been reading that if you hook up the 12volt to the 6v you need a regulator to bring the 12v down?

Basically I need to know if I get a new gas gauge and a new sending unit, is it okay to hook it up through my wiring harness as a 12-volt or do I need to purchase something to reduce voltage.

 

Depends on the gauge. The sender doesn't care what the voltage is, but the gauge probably will. A typical solution is to use a voltage regulator, such as LM7806 to drop the voltage to 6 volts for the gauge. This regulator can only handle a limited amount of current, so only use it for powering one gauge.

 

also, you can usually test a sending unit by measuring it's resistance (usually between the wire from the gauge, and ground). Typical resistance values will be from zero to 300 ohms, and some are higher when the tank is empty, some are higher when it's full. If you do some research and find the resistance that the sender is supposed to be both empty and full, you can substitute a resistor for the sending unit, and see if the gauge reads what it is supposed to. For example, some later Mopars have 73 ohms empty, 10 ohms full. If you connect a 10 ohm resistor across the sending unit wire and ground, it should make the gauge read full. If you use a 75 ohm resistor, it should read empty. Be sure you're using the correct values for your particular car, and also that the gauge has the correct voltage supplied to it.

 

One other thing to consoder is that the 55 is positive grounded.

 

Thanks so much I'll get back at it and see what I can figure out!

 

When I did my rewire the gauge reads backward, and intermittently. My entire system switched over to 12v Neg ground, which is probably why the gauge is reading backwards. I'll be replacing with a12v sending unit and tinkering with reversing the terminals to get it all working again.

Let me know what works out for you.

Sent from my SAMSUNG-SM-G900A using H.A.M.B. mobile app

 

Keep that 6v starter. When you hook it up to 12v you will have a high speed starter!