The Stovebolt Site Forums The Shop Area The Electrical Bay from 6v to 12v guages

hi,before i aquired my truck the previous owner changed it from 6v to 12v. none of my guages work even the speedo (which i need to take a look underneath). the fuel guage goes up to half and just stays there even when empty!
aftermarket amp and temp guages have been fitted but i want to get the original ones working. they light up when the lights are switched on but the guages just wil not work. is there something i have to fit to them because of the conversion to 12v?

The amp gauge works the same on 6v or 12v, it is just showing current direction. Unless the temp gauge/sending unit was replaced with an electric one, it does not take power except for the light. It is a continuous unit from the bulb to the gauge. If damaged it won't work. The speedometer does use electric power except the light. The gas gauge issue is better addressed by doing a search. There are several common problems and trouble shooting guides that can be found fairly easily.

Chuck

The fuel gauge usually burns up if it does not have a resistor (not always some say). If your tank has never been cleaned you may find it is the float gauge itself that is the problem (crud & corrosion). Speedo could be internal mechanism or the cable no electrical connection there. Also the oil pressure is a tube from a lower block fitting to the gauge, no electrical. It is a small 1/8" tube they can plug up or get pinched. Usually the amp gauge if hooked up correctly functions fine on either voltage. Temperature gauge will come from the rear of the head with a copper or steel tube to the gauge. Look for breaks in the line (sealed unit) if the ether has leaked out you will need to replace it, no electrical connection. This is a continuing topic here so search for specifics others will chime in as well.

UK,
Please advise what year truck you are working on. Also what is your name? I like to know to whom I am speaking. It makes for a more friendly forum.
Thanks,
Harold

hi harold, my name is bill and i am 53 yrs old. i have only very recently imported my truck from texas to the UK (arrived here on the 13 april). the year of my truck is 1950 and has had some mods.
i think the reason behind things not working correctly is the engine/trans has been replaced by a 350 small block and auto box. i did want to get a truck as close to original as possible but this one came up with a good price and had no rot at all.
i really need to get a real good look at the truck which is a bit difficult at the moment as it hasn`t stopped raining here since i got it. i just thought i would ask a few questions about some problems i have to give me a head start on things.
thanks for all the replies guys, all are much appreciated. this is a great site and very useful.
thanks
bill.

If you have to replace the temp gauge they make one with a longer tube for use with a V8. Like others have said; amps are amps, either 6 or 12v, and the oil pressure gauge is the tube fed mechanical type. The gas gauge will need a voltage reducer, you can buy a Runtz ($20) or one off ebay for about $3. Once you have the reducer or if you have a 6v battery handy you can run a wire to the "I" (Ignition) terminal on the back of the switch and a ground wire to the "S" (Sender) side. If the gauge goes to full it's alright.

Should have said to the "I" terminal on the back of the GAUGE.

thanks for the info evan. would i wire the reducer in line to the ignition terminal on the guage? and any ideas on the speedo?
thanks.

Bill,
This may be of great help to you while working on your 1950 Chevy.
It is a copy of the Chevrolet 1929 - 1954 Master Parts & Accessories Catalog http://chevy.oldcarmanualproject.com/1929_54chevyparts/index.htm Also check out the Tech Section. It has a lot of great information.
http://www.stovebolt.com/techtips/

Best of luck on your project.
Harold

thanks harold. i have been working on the truck over the weekend and discovered the window mech was quite new but the crank has snapped off, i have just got an origonal replacement off US ebay FOR $35. the window track had also come free of the window and there seems to be some sort of black mastic in the window guide attached to the vent side window which was holding it in real hard, this is prob why the crank snapped. i will have to sort that out before i fit the new regulator.
i have also cured my starter problem and happy to say the truck now starts ok.
just have to have a go at the guages next, i got the oil and amp sorted just got to get the fuel gauge and speedo done.
thanks for all your advice guys. a great help.
bill.

i have found out why the speedo dont work, the cable has melted on the headers it has bee routed from the auto box to the speedo right along side of them and the heat has washed it out.
i now have another problem, the lights etc, sometimes they work sometimes they dont. still has the old cotton braid wiring that is splitting and been repaired in places with bits of tape also my amp meter is showing low but the battery is working/starting fine. do you think i must have a short in the loom somewhere? might be best to replace the loom in case i get an electrical fire or something.

Here are some diagnostics for the fuel gauge system parts and wiring.

This voltage reducer works fine. The reducer goes on the ignition (power in) side of the gauge. It is directional and is made to be attached to the post on the gauge.

thanks tim, i have been working on the trucks electrics and what a mess they are, at the moment i have both gauges out and need to get the light switch out to check a few things.
got all the lights working apart from both headlights, need to check the units first i suppose or the switch? any ideas chaps?