Hello All,

Several of my dash gauges, fuel, temp, oil are not functioning. I'm wondering the best way to figure out if it's the gauge or sending unit that has gone bad? Assuming for now that the wiring and ground are good.

Thanks,
Paul

 

The fuel, temp, and oil pressure gauges all require a good ground as well as power. Do you have power to the gauges? Is the gauge cluster properly grounded. Might help to know the year and model of vehicle, the system voltage, and if any mods have been done.

 

It's a 1950 F1 Truck. It's still running the 6V system. The speedometer and battery gauge work so I believe there is power to the system. As far as the ground, where do they typically run the ground to for instrument panel?

Thanks!

 

The instrument panel is grounded by metal to metal contact to the truck.

FYI, the speedo is just a mechanical device, no electricity needed.

 

To test the gauge unit (works for all except ammeter), take a "C" or "D" cell battery and connect it across the gauge after disconnecting the sending unit lead. The gauge should read 1/2 scale. This is described in the workshop manual in great detail.

 

Ross, I never knew that. I'll check the 54-55 shop manual. I never saw that but of course there is one much info there. Thanks!

 

Albuq F1

Your advice and Fig. worked like a charm. My shop manual had a different version of Fig. 93 and it wasn't as clear as your directions. So I was able to determine that all three gauges did work when I tested them. After spending the day under the dash I was able to determine a couple of modifications that were made to the original wiring. Someone along the way installed turn signals and a speaker in the dash. I was also able to determine that the 6 V system is a positive ground system. At this point am I wrong to assume that with the modifications made to the system that it's probably the ground that is faulty for the panel? I tried to trace the ground wire From the three gauges but it led to a wrapped bundle and it was tough to tell but it seemed to lead to the ground on the back of the firewall right underneath the regulator. Is this where the instrument panel is typical grounded? I guess my big question is how do I test to make sure that is a good ground and is it different because it's a positive ground system?

thanks again!

 

I should have stated my diagram is an edited version specifically for using a battery.

For the BonusBuilt trucks, the ground for the instrument panels/gauges are pretty much the retaining clips holding them into the dash. I don't recall a dedicated wire for grounding. That's why there are often gauge problems after painting. You can certainly run a ground wire to something under the dash that is clean steel.

 

Ok so I just relized the Fig. above tells me the ground or B-G wire is running to the ignition switch but where does it go from there?

 

The wire going to the ignition switch is NOT a ground, it's hot (power). What year is your truck? on 48-52's there is a sheet metal strap, not a wire, from that terminal on one gauge to the other gauges to power them. The ground is the case of the instrument to the dash (or add a wire as I added above).

 

It's a 1950.

So if I am to add a ground wire, should I attach the one end to the top mounting bracket of the instrument panel or is there a better location on the panel for that end of the wire?

 

IT DOESN'T NEED A GROUND WIRE, as I and Ross have stated.

 

Really Abe thats not what I took form his post! I'm obviously new at this and am really trying to pick it up and do it myself. If you are frustrated with the questions I'm asking feel free to troll a different post.

Ross thanks again for taking the time to help me out, it's very much appreciated.

 

Hey Pezlo,
Welcome Aboard! It's good to see another '50 getting restored.
Post some pics when you get a chance. Abe is a good frequent contributor here - he's not a bad guy. Hang in there keep asking questions.


Ben in Austin
1950 F1 (351W/AOD)

 

Hi there Pezlo,
Do you have a voltmeter or test light to see if power is getting to the gauges?
Power from the ignition switch should be to the gauges when the ignition is in the "ON" position. And as Ross stated, power is connected from gauge to gauge with metal strips. This is where I would test first. Your grounding is probably ok.
...Terry