Stock gauges wiring questions

T

Tauber

Junior Member
I have a 1950 F1 and I am trying to get the stock gauges to work again. The truck has been converted from 6v to 12v and from the poking around on the web that i have done i have found that 12v will work with the 6v gauges. is it necessary to get a voltage reducer or can i directly wire to the gauges?

At this moment i am mostly worried about getting my gas gauge working. from what i have read the gauge has a I,S and G terminal. however, the stock fuel gauge only has 2 terminals. in the picture below which terminal is for the hot wire and which is for the sender unit and what do i ground it to?

Finally, if a voltage reducer is needed, i have an after market fuel gauge that i could use in the mean time. but i have a question about that as well. this gauge has the I,S and G terminals so i know which wire goes where on it. i just need to know if i need to run 2 ground wires on it as there are 2 ground terminals, where can i ground them to and what gauge wire do i use for the ground wire?

Thanks for any help with this.
Tauber
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Tauber,

I recommend you check out

http://www.fifthaveinternetgarage.com/

Randy Rundle sells individual gauge voltage reducers and also has a 6V-to-12V conversion manual that is a huge help in understanding the change.

As for the gauges and your questions:
1) Will they work on 12V? Yes, but not forever. My 47 COE (converted to 12V) was improperly wired and had almost 12V at the gauges. This had been this way for some time and the gauges never burned out but I didn't wait to test how long it took. I got the voltage reducers. Also, I don't know if you will be able to maintain any accuracy in the readings if you use 12V on 6V gauges. The 12V won't affect gauge needle operation but the 12V will affect the sensor readings so you might not show useful info...don't know.

2) When selecting a voltage reducer, pick a Runtz-style (see website above, also available elsewhere). Don't use a big 12V to 6V resistor drop designed for horn or light use. These resistors require more current than the gauges will draw to drop a full 6V. The Runtz and other similar reducers use a solid-state circuit to regulate the output voltage. Also, these are tiny enough to mount on the back of the gauge and they won't be seen. For a car with oil, temp, fuel and amp gauges, you'll need 3 - the amp gauge doesn't need one. They best work with one gauge only, hence the three.

3) As for the gauge posts and which connect to what, I don't recall off-hand. Check a truck wiring diagram (even a stock one will show which connections go where even if your 12V conversion is dramatically different). If you still need help, I'll have to go look at my cars...PM me if need be.

Hope this helps,

COE Dan
 
I just did my 50 f1 to 12 volt, and bought 3 runtz reducers they work great, did not do anything for my amp guage yet.
 
If you use Runtz reducers 1 is needed per gauge. An ammeter will indicate the amps on either voltage. If the system was changed from + to - ground the wire that that goes through the loop has to be revesed. A volt meter requires a 60 ohm resistor wired is series to read correctly on 12 volts.
 
There's also a guy on e-Bay who sells a reducer that works well. It is a single reducer for all three gauges. I've used the Runtz units on a prior occasion, but I much prefer the single unit.
 
Please clarify this information

41Ford1 wrote "If the system was changed from + to - ground, the wire that that goes through the loop has to be revesed."

Can someone please tell me what loop he's referring to and which wire ? Is this a wire that goes to the gauges or another one ?

thanks for the help-
 
He's referring to the loop on the back of the ammeter that the charge wire runs through. The ammeter works by induction, and if you change from positive ground to negative ground (as most 12v systems are), you must reverse the direction of the wire through the loop to keep the reading correct.
 
Henry himself used 6 volt gauges on a 12 volt system until 1986 (except for 1956). A Cluster voltage regulator is used to cut the voltage to a 6 volt pulsed output to the gauges. A 1959 CVR is available from NAPA and works well. I have used them many times and have also used later gauges from 12 volt cars and changes the face and needle from the early gauge without any problem. Why someone would use a Runtz (not to say they don't work) or any other aftemarket voltage drop is beyond me. The factory used 6 volt gauges from model A days straight through 1985 with no problem, so why not use a method proven on literally millions of cars? I just finished a rewire to 12 volts on a friend's '49 coupe using the 1959 CVR and it owrks perfectly
 
We switched to 12v in our 53 Victoria. The only gauge that's working is the ammeter. I put Runtz reducers on the fuel & temp gauges and they're still not working at all. They're pegged, fuel all the way on Full and temp pegged at Hot.

I don't know how easy it is to fry the 6v gauges by running the car with 12v hooked up to them prior to using a reducer ? The car was driven very little, 3-4 times for no more than a total of 5 miles.

Thoughts/Suggestions ?
 
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