Gauges not working after rewire?

J

JimNNN

Well-known member
Hi everyone! Been almost 5 years since I've been to the Ford Barn. Glad to be back!


I just rewired my '54 wagon with the original v-8 engine. I did everything but the overdrive, which I'll tackle later this year. I'm also waiting to install the new heater motor and some other heating components that I've refurbished until I can flush the coolant when the weather gets better.



I'm happy to say that the project has largely been a success. I've rewired it in 6 volt with a universal kit from Ron Francis, but it is in negative ground instead of the original positive ground. (The car was changed to neg. ground many years ago before I bought it.) My car is a bare bones Mainline, so it didn't come with a lot of electrical options, but most everything electrical is now working like it should, and the charging system and turn signals are much improved. (With the exception of the overdrive electrical components, most devices - starter, generator, relays, senders, switches, regulator, etc. - have been replaced with new or rebuilt.)



The only negative is the fuel gauge and coolant temperature gauge (which are both original to the car) aren't working. I should say that the fuel gauge never worked or never worked like it should - but I was never sure if it was the sender, the gauge or the wiring. Not exactly surprised that it wasn't working after being rewired.


The temperature sending unit is new, but the fuel sender is original as it's extremely difficult to find new ones made for the station wagon gas tank (which is also hard to find.)


I rewired the car because of a bad short I had in an ignition switch last year. I figured that the temp and fuel gauge got fried/ruined when the short happened, as they were both wired to the ign. switch ion the original configuration.



Fuel gauges are hard to get, but I was able to get a new old stock temp gauge on ebay the the seller said it had been tested and was good. Unfortunately, after installing it, the new temp gauge isn't working either. I was surprised. I followed the instructions in the Ron Francis wiring kit and used the wiring diagram in the shop manual as a guide to figure out how the gauges were to be wired.


The circuit labeled "gauge feed" on the new wiring kit is working - it also powers the generator and oil pressure idiot lights, and they both are working. Tried providing an extra ground to the temp gauge in case the instrument cluster ground as inconsistent, but no luck.


Any ideas?



THanks.
 
I do not think the temp gauge will work being as original was positive ground same goes for fuel if everything else is right it would not hurt trying to switch cables pos-neg then try even the starter does not care the only problem would be the radio if it was replaced by aftermarket neg ground this is only my guess this only applies if they were working before rewire
 
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Have you tried checking the gauges with an Ohm meter? There should be 'continuity' between the terminals and thru the coil inside the gauge. If not, the heating coil is burned out. See the diagram below.
The heating coil in an oem gauge is not polarity sensitive. But if it's a reproduction or after-market part that's another story.

If the gauge is in the dash... a common test (with the power on) is to temporarily ground the wire that's connected to the sender to see if the gauge needle moves, that tests the whole circuit (except the sender). A fault anywhere will prevent the gauge from working so in your case you need to isolate and test the individual parts of the circuit.
 

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dmsfrr said:
Have you tried checking the gauges with an Ohm meter? There should be 'continuity' between the terminals and thru the coil inside the gauge. If not, the heating coil is burned out. See the diagram below.
Click to expand...


I have not tried that...thanks for the suggestion!



A heating coil in an oem gauge is not polarity sensitive.
Click to expand...


As to the polarity thing, I believe dmsfrr is correct in this statement because my temp gauge worked great for fifteen years with the car being in negative ground. As I said, the car has been negative ground since I bought it, though it came from the factory pos. ground. The temp gauge stopped working after the car was rewired and the supposedly OEM NOS gauge I bought to replace it isn't working either.





If the gauge is in the dash... a common test (with the power on) is to temporarily ground the wire that's connected to the sender to see if the gauge needle moves, that tests the whole circuit (except the sender). A fault anywhere will prevent the gauge from working so in your case you need to isolate and test the individual parts of the circuit.
Click to expand...


Thanks again. It's strange - as I said, the fuel gauge never worked but would sometimes I could get slight movement out of it when the car was running...but that was before the rewire. Now its as dead as a doornail in the empty position.



Another strange thing: I seem to remember that when I turned the ignition off (before the rewire) the temp gauge needle would go to the cold side of the register. Now it stays pegged at the hot side of the register all the time...connected or disconnected. I might be "misremembering" though, because most if not all of the used or NOS temp gauges I see online have needles that are pegged in the "hot" position.



Can anyone with an original 6 volt temp gauge in their '54 Ford tell me if their needle goes to cold with the car turned off? I can't recall because I have other old cars...and I may be mixing them up. :)


Thanks for all the responses so far.
 
54vicky said:
I do not think the temp gauge will work being as original was positive ground same goes for fuel if everything else is right it would not hurt trying to switch cables pos-neg then try...
Click to expand...
If the oem Temp gauge is good I don't believe it matters if the car is set up + or - ground.
In any case, reversing the wires on the back of the gauge would fix that problem, if it occurs.

Test both the Fuel & Temp gauges with an Ohm meter to see if they're good.
"The fuel and temp gauges ... are not polarity sensitive."
(from this link)
https://www.ctci.org/gilsgarage/6to12.php
 
As dmsfrr stated, the two gauges are not polarity sensitive. I have the stock gauges in my 54, converted to 12 volt and they are ok.. You should be using a voltage drop on the two gauges, like the one that came on 57 and up Fords, but not sure that is the solution.
 
Some gauges respond to a D cell battery check. If 6-volts direct gives a full indication the 3-volt D cell battery arrangement will read 1/2 full. That will test the gauge. The old King Seeley fuel senders generally need the tiny little points on the bimetallic heater strip cleaned to restore function. They provide the pulsed current to operate the gauge. The cap on those senders can be pried off without damage if a person is careful.


The old King Seeley coolant temp gauges read full hot when the ignition key is off. This is how they worked in the flathead days anyway. A careful application of low voltage should get the meter to move on those too. The senders can't be repaired if they are bad.
 
Just wondering...

What was the reason(s) you went from 6V POS GRD to NEG GRD but not a full 12V conversion?

Is that the only way the replacement harness was offered?
 
KULTULZ said:
Just wondering...

What was the reason(s) you went from 6V POS GRD to NEG GRD but not a full 12V conversion?

Is that the only way the replacement harness was offered?
Click to expand...


Hi Kultulz. Thanks for your replies.



The main reason I didn't go with the 12 volt conversion is the overdrive unit, which is original to the car. I can get a 12 volt solenoid and relay for the borg-warner unit I have, but they are very expensive. I estimate that the new 12 volt versions of those two things would've added another $600 to the project. The ones I'd found are way overpriced, IMO.



I've heard that stepping down the voltage from 12 volts in order to keep my original 6 volt OD relay and solenoid shouldn't be done. That may or may not be correct, but I didn't want to use my car as a guinea pig, especially since I'd never rewired a car before, so I stayed with 6 volt.



You are correct, the replacement harness was offered by Ron Francis nominally as a negative ground. The customer support guy I talked with strongly suggested I go negative ground, and since I got the car that way, that was fine with me. It was a "universal" kit, and from what I've read, the old 6 volt GM cars were all negative ground, so I guess the Ron Francis company decided negative ground was the way to go for the average customer.



As far as my gauge dilemma goes...I just cheated.:) Yesterday I bought a mechanical water temp gauge because I'd thought about getting one before my electrical problems last year. The mech. gauge gives me a lot more useful information than the original unit:



First, it's numerical rather than a "C" and an "H" with a needle somewhere in between. Second, the mechanical unit was easier for me to test (for accuracy) by putting the probe into water coming to a boil and seeing how close to 212 it got ( it was at 208.) Third, when I would shut off the car on hot days, the gauge would sometimes continue to go up - it would peg on "H" and I couldn't know how hot it was actually getting after I turned the ignition off. (It was cold today, but the needle went another 12 degrees F higher after the car was turned off. Don't know what it'll be in warm weather.)


I'm not an originality nerd, but the smooth running engine has never been rebuilt, so I guess I make some effort to keep the spirit of originality without going overboard. Wish I hadn't spent the money on the NOS gauge, though (50 bucks) but I tried it, failed, and decided to go aftermarket rather than waste time.
 
JimNNN said:
The main reason I didn't go with the 12 volt conversion is the overdrive unit, which is original to the car. I can get a 12 volt solenoid and relay for the borg-warner unit I have, but they are very expensive. I estimate that the new 12 volt versions of those two things would've added another $600 to the project. The ones I'd found are way overpriced, IMO.
Click to expand...

Copy...

Third, when I would shut off the car on hot days, the gauge would sometimes continue to go up - it would peg on "H" and I couldn't know how hot it was actually getting after I turned the ignition off. (It was cold today, but the needle went another 12 degrees F higher after the car was turned off. Don't know what it'll be in warm weather.
Click to expand...

... hmmpf ...

If the gauge was still working after shutting off, I would think it is showing engine heat soak temp as the water pump stops turning. I need to cipher on that one.

THANX!
 
If the key is off, the gauge goes to it's shut down state. More modern gauges go to full cold and older king Seeley gauges go to full hot. Most engine rise In temp after shut down due to no coolant circulating. As soon as the engine is cranked up again the temp will go back to normal.


The overdrive solenoid will work on 12-volt for a long time according to a lot of folks that have run them that way. Purchase a used one of the same shaft length & bolt pattern manufactured after 1957 will get you a 12-volt one. Many times, only the internal points need cleaning. There used to be some folks that would rewind one with a bad coil or coils but I don't know if anyone does any more.
 
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KULTULZ said:
... hmmpf ...

If the gauge was still working after shutting off, I would think it is showing engine heat soak temp as the water pump stops turning. I need to cipher on that one.

THANX!
Click to expand...


Yes, that's what I believe is happening. No pump getting water from the radiator and no cool air flowing over the radiator, anyway. I've always wondered how harmful this is to old engines without the independent running electric fans. Not a problem on these cold days, but when it's 90 degrees outside? It'll be interesting to see what the gauge says when summer comes.
 
when I did my wagon converted to 12 volts used the factory gas and temp gauges used a voltage step down from a 60's mustang every thing worked I fit the amp meter with modern internals from a volt meter and left the gauge face stock I think I might have changed the temp sender
 
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