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Topic Review (Newest First)
04-07-2007 07:07 PM
goshawks00 Thanks doc , nice post....!!!
I have found them all over the web from $.50 up to $30.00 The RS I went to and another that I called both said they no longer carried them with anything near those values. I didn't believe them and went to RS website and darned if they don't have them anymore. Thanks for the info , I'll get one some how. Of interest was the number of sites that carry them for guitars , so possibly a good music shop (that does repairs) may also have them. Doc again I appreciate the time you send on all of us... may your 'vettes go faster because of it<G>
Barry
04-07-2007 06:26 PM
docvette Doc here,

Dude..where do you live?

Our town is so small, we have One main street, That is only 4 miles long..has 17 sworn Cops ..and ALL 17 of them are busy pulling over street rods for headlight violations..and loud mufflers (Because they Can..A REAL Andy of Mayberry Deal Here..)

Our local Radio Shack Is like 15 to 20 feet wide, and about 70 feet long..Shoehorned between a Flower store AND a Restraunt..and THEY have a bin full of (Close Matches) Them...

We had a guy a few months back do this SAME job, got one at HIS local Rat Shak..and installed it and it went well...

That is the trouble with RAT SHAK, No two of them are alike..Since they went into The $$ is in SELL, SELL, SELL!!.. never mind what they actually may want..:

"You Got Questions? We've Got .....

Cell Phones..
Batterys...
Sprint Contracts..
Sat TV Installations...
Plasma TV's.. "

Questions? ask Mr Wizard...I need to finish my Homework for School in the morning.."


They have slowly Been Phasing out the component parts as they sell out...since about 2002..(Which may be Why we still have a bunch of them..since I am the only one buying them..)

DO you Have a local FRY's Electronics Store NEAR you?

Go there, on their Electronic Component Isle (AND be advised they are a mess..parts NOT on hangers just thrown on the floors and end caps..SO you HAVE to get on your hands and knees and look..Go to Resistors, Potentiometers, Then Tapers ..Here is what to look for...

ANY Pot that Is 1 WATT or more, has a resistance Value of 0 to 100 Ohms Or more, up to 500 ohms...(by using half the pot Center terminal and right terminal will give you a range of 0 to 250 ohms....tighter adjustment range but works fine..) and go with that..

IF that does not work for you..Get out the PHONE book..look for Electronic Parts suppliers..PHONE them First..ASK for a pot near the values I gave you..IT does not have to be exact..(remember..It's adjustable...) as long as it is 100 ohms or more and 1 watt or higher..and see what they may offer..They should have one...

The reason you got such a high price on the one you found is because it is a Rehostat..a BIG ceramic Wire wound adjustable resistor that controls high current apps..like lamp dimmers..not what you need or want..you want a POT..

If you Crap out locally all together, go Here:Ohmite Phone or EMAIL them with the spec's I gave you..Tell them you want a type AB, style CLU and what range..Their site Say's their pots come in ranges from 50 ohms to 500 Megohms..and order one..

FROM THE OHMITE SITE:


Doc
04-07-2007 04:38 PM
goshawks00 NEXT, get a Linear taper potentiometer, (like an old radio volume control ) (rat shak ,$3,00) Say, your system is 0 to 60 Ohms , get your linear taper (pot) within a range of 0 to 100 ohms at 5 watts..

Doc after driving 30 miles to the nearest Radio Shack
I asked for said potentimeter, only to br told they don't carry sucah a creature ... the best they had was a 1k @.25 watts. I told sure you do Doc said so, well that made them look it up in their catalog athen they told me they don't carry anything even close. Any ideas where to find a 0-100 ohm @5watt pot?
I did find one close from an electronic store on the internet:

Wire wound element - Continuous rotation -Gold plated plug on terminals - Brass bushing - Stainless steel shaft
Standard resistance range : 50,100, 200, 500,1K, 2K, 5K, 10K
Electrical angle : 350 degrees
Power rating 0.5 watt
Life expectancy : 1,000,000 turns
Options: Ball bearings, center tap, multiple gangs, sealed body , o ring shaft seal, servo mount,
continuous rotation, flattened , lengthened or rear shafts dual concentric shafts, for wirewound version see SP22B
but they start @ $30.00
Ideas?
Barry
04-06-2007 08:06 PM
docvette
Quote:
Originally Posted by goshawks00
Doc why does the gauge go up to full when grounded then if the gauge is damaged?
Doc here,

See, that is NOT what you said..

Quote:
Originally Posted by goshawks00
Update--- I reattached gauge to six volts..... the gauge goes up to "E" with the key on. With key turned off the gauge goes way below( like as far as it physically can) "E".

Disconnected ( actually cut wire mid way between gauge and sending unit) as figured I'd need to add in a potentiator. The guage does not not move at all with key on, still bottomed out.
Disconnect the sender Wire at the back of the gauge..turn key on..watch gauge..goes to full..its working...the sender wire is bad..If it does not go to full .. the gauge is toast..(or needs the sender to ground instead of opening the sender wire to climb to full) IF it does go to full (in either mode) the wire OR sender is bad...

Your posts indicated the scale was now between E and sub E, which was the way I read it, If you get a full scale sweep on the gauge by grounding/ungrounding the sender wire AT 6 volts AT the gauge (not downstream) it is working..leave it alone..just put in the calibrating pot..as I posted, and calibrate it as I said..

Doc
04-06-2007 07:47 PM
goshawks00 Doc why does the gauge go up to full when grounded then if the gauge is damaged?

As far as the gauge goes I have two other gauges which all test the same +-60 ohms empty and 10 full and I will replace one to test whether or not the gauge is off or wired backwards which is not likely.
Thanks doc for your thoughts ,
barry
04-06-2007 07:26 PM
docvette
Quote:
Originally Posted by goshawks00
Hmmm.... Let's see... the original system was 6v positive ground , but everything is now 12 v. neg ground.

The gauge is self grounding to the housing I think as there is no ground wire to the gauge ... which only has 2 connections... one is power ( now 6v) and the other wire goes to the sender.

Could I possibly have the sender power wires mixed? (Actually I don't think so as there is a metal plate that goes from gauge to gauge to carry power to the next gauge .
Barry

Doc here,

After a good night's sleep , (after 22 hours of designing our new product line this year..) and re~Reading what you have described..here is what exactly I think you have done..

By putting 12 volts straight on a 6 volt gauge, and with a disconnected sender wire, you Drove the meter movement way past it's mechanical limits backward......damaging the index pointer and the jewel it rides on..now the highest reading it can give as "E" .. and the lowest being Sub "E"...(moved the whole scale backward)

You Can try to pull the gauge apart and "Right" the pointer IF you are careful and patient.. and VERY Lucky..

Or pack it up and send it off to a restorer (I have links) that will install a new movement, bezel, silk screen the face and install new glass for about $250.00..(I'm assuming this is a retro Stock gauge that matches the panel) ..

This is a SMALL example of WHY I dislike Mixed busses (6 volt / 12 volt on the same vehicle..) sooner or later the wrong wire ends up on the wrong device..and "Poof" you let out all the factory installed Smoke..

Doc
04-06-2007 10:09 AM
goshawks00 <<Doc here,

Sounds like you also have power and ground reversed at the gauge too..

Doc >>


Hmmm.... Let's see... the original system was 6v positive ground , but everything is now 12 v. neg ground. The gauge is self grounding to the housing I think as there is no ground wire to the gauge ... which only has 2 connections... one is power ( now 6v) and the other wire goes to the sender.

Could I possibly have the sender power wires mixed? (Actually I don't think so as there is a metal plate that goes from gauge to gauge to carry power to the next gauge .
Barry
04-06-2007 09:34 AM
docvette
Quote:
Originally Posted by goshawks00
Update--- I reattached gauge to six volts..... the gauge goes up to "E" with the key on. With key turned off the gauge goes way below( like as far as it physically can) "E".

Disconnected ( actually cut wire mid way between gauge and sending unit) as figured I'd need to add in a potentiator. The guage does not not move at all with key on, still bottomed out.
Barry

Doc here,

Sounds like you also have power and ground reversed at the gauge too..

Doc
04-06-2007 09:30 AM
docvette
Quote:
Originally Posted by goshawks00
Thanks Doc, I do have a meter but don't know how to use it (sic) . I can try going back to 6 volts and see what happens,
DOC here,

NOW is a good time to learn how to use it..


Quote:
Originally Posted by goshawks00
but I STILL would like to know why the test light flashed when I probed the sender wire. Actually a better way to describe it is that it pulsed, as in flashing on and off and on and off? All lights are wired 12v with appropriate bulbs.
WHY it flashed is of no importance..the FACT that it did..IS..you are testing in DANGEROUS waters..

Quote:
Originally Posted by goshawks00
>>The SENDER wires NEVER have power on them for Fuel gauges (like putting a 12 volt fuse on 50 sticks of liquid dynomite..) FUEL SENDERS are always referenced to ground through a potentiometer..>>

not sure what you mean does it matter whether it's 6v or 12v as far as 50 sticks of dynamite senario?
1, 6 or 12 volts..with you "probing " around with power..into a connected sender line you are heading for one hell of an explosion and fire..

You are sending 12 volts (or whatever voltage you have) Through a sender (that should be on ground) INTO and through 30 GALLONS of gasoline and inside of a grounded tank..IF you didn't read and fully understand my last post...you need to read up on fuel senders and systems, and learn to use the meter OR find a good shop to repair the system to be safe..your headed for BIG trouble.

Doc
04-06-2007 09:19 AM
goshawks00 Update--- I reattached gauge to six volts..... the gauge goes up to "E" with the key on( probably did before but I didn't notice it). With key turned off the gauge goes way below( like as far as it physically can) "E".

Disconnected ( actually cut wire mid way between gauge and sending unit) the wire going to the sending unit the guage does not not move at all with key on, still bottomed out.
When I ground the wire it goes to past full.
Barry
04-06-2007 07:41 AM
goshawks00 Thanks Doc, I do have a meter but don't know how to use it (sic) . I can try going back to 6 volts and see what happens, but I STILL would like to know why the test light flashed when I probed the sender wire. Actually a better way to describe it is that it pulsed, as in flashing on and off and on and off? All lights are wired 12v with appropriate bulbs.

>>The SENDER wires NEVER have power on them for Fuel gauges (like putting a 12 volt fuse on 50 sticks of liquid dynomite..) FUEL SENDERS are always referenced to ground through a potentiometer..>>

not sure what you mean does it matter whether it's 6v or 12v as far as 50 sticks of dynamite senario?

Thanks,
Barry

BTW went to the light rather than chime for key on /not running. Thanks again.
04-05-2007 11:12 PM
docvette Doc here,

If you HAD a 6 Volt gauge and YOU wired it to 12 volts, It's probably damaged now..replace it.

Or wire it back as 6 volts and do this:

Quote:
Originally Posted by docvette
To test your sender, remove the sender wire, and watch the gauge, it should peg at full, If it does, then ground the sender wire, it should peg at empty or opposite the last reading, If you have this the system is whole and working.
IF you are lucky it may have survived.

You CAN NOT accurately test ANYTHING with a test lamp..(except to know power comes from somewhere through the lamp to ground..) USE a meter. Most likely you were seeing a path to ground through the meter or the sender wire lighting the lamp..but you can't tell without using a meter..

The SENDER wires NEVER have power on them for Fuel gauges (like putting a 12 volt fuse on 50 sticks of liquid dynomite..) FUEL SENDERS are always referenced to ground through a potentiometer..

Quote:
Originally Posted by docvette
The Sender wire is a RESISTANCE to ground through the sender which IS a Variable resistor mounted on a float aparatus..The higher the float arm moves up, the more resistance (or less depending on the sender configuration) the more resistance the gauge See's, the more the needle drives upward..( "F" ) ..the lower the float, the reverse becomes true.. ( "E" )..
SEE ILLUSTRATION ABOVE.

I'd wire the gauge back to the 6 volt config, and try the above sender test..if it is dead (no meter movement at all) ..get another gauge you hosed it..If it pegs the sender wire is shorted (or open) ..find the short / open and fix it..

Doc
04-05-2007 10:52 PM
goshawks00 Yes the original sstem was 6v converted to twelve at some point with a drop down for the gauges. With the fuel gauge wired thru the dropping resistor , I checked the sending unit wire for power because the gauge wasn't working. At that point the testor light would flash and the gauge wasn't registering anything.... why was the testor light flashing?

I rewired the fuel gauge making it 12 v. and disconnected the wire that took went from other side of gauge to the rest of the gauges so it was not sending 12v to the rest of the gauges and made them run off the drop down. So now I only have 12v to the fuel gauge. The other wire from the fuel gauge is the sender wire, as the gauge is grounded.

Wired that way when the key is on the gauge goes to full. If I understand you Doc , I should wire a Linear taper potentiometer somewhere along the sender wire. Correct?
Thanks,
Barry
04-05-2007 07:39 PM
docvette
Quote:
Originally Posted by goshawks00
Hooked up the fuel gauge through a 6 volt resistor as all the original gauges were 6 v. the rest of the car is 12v.
I got no signal... tested the wire going to the sending unit and the test light flashed. Switched the fuel guage to 12 v and guage is working but registering full, even though I have a measued 1/2 tank ( 12 gals in a 24 gal tank). Is there a rule of thumb about adding resistors to bring the guage and tank into sync?
barry
Doc here,

First, there are no 6 volt resistors..Resistors are measured in ohms and watts to determine how many amps at what voltage they will be operating at..That rule of thumb is Called Ohms law..(and a little math)..

IF you meant, your gauge WAS a 6 volt system, AND you Converted your Car to 12 volts , and used a dropping resistor on the power wire, it would be : 6 volts out, with a draw of about an amp, = 6 ohms..At about 6 watts (unless my confuser slipped a digit) from 12 volts..

IF the gauge was 12 volt to begin with and you added a resistor to the power wire..It won't work at all..

A Calibration resistor needs to be installed on the sender unit wire ONLY , not the power wire. The Sender wire is a RESISTANCE to ground through the sender which IS a Variable resistor mounted on a float aparatus..The higher the float arm moves up, the more resistance (or less depending on the sender configuration) the more resistance the gauge See's, the more the needle drives upward..( "F" ) ..the lower the float, the reverse becomes true.. ( "E" )..

IF your gauge IS supposed to be 12 volts, remove the resistor from the power wire. and reconnect as per stock.

To test your sender, remove the sender wire, and watch the gauge, it should peg at full, If it does, then ground the sender wire, it should peg at empty or opposite the last reading, If you have this the system is whole and working.



If not check the Sender wire for bad connections or cuts, be sure the tank sender has a solid ground wire to the frame too..If the wire is good check (or replace ) the gauge.

If it is reporting in error, you need to find the PROPER resistance of the sender unit / Gauge..usually 0 to 30, 0 to 60 , 0 to 90, or 0 to 120 Ohms , up to 290 ohms, (your parts guy should be able to tell you by the make and year of the vehicle, or post it here, I can look it up..)

NEXT, get a Linear taper potentiometer, (like an old radio volume control ) (rat shak ,$3,00) Say, your system is 0 to 60 Ohms , get your linear taper (pot) within a range of 0 to 100 ohms at 5 watts..

locate an easy access area that you can mount the pot along the sender wire from the tank..cut the sender wire..

Strip and attach the wire from the tank and solder it to the left terminal AND the center terminal of the pot..insulate with shrink tubing.

Strip and attach the wire going to the Gauge to the right terminal. Solder and Insulate with Shrink tubing.

That's it,.... Now to Calibrate..Drain (or run it out of gas) , and add 2 gallons of fuel. Monitor your gauge, it should be about "E"..

If not , Turn the pot in one direction or the other, watch the gauge, one way will go up the other will go down. as you turn the pot knob..

Set it for "DEAD ON" "E"..this way , you will ALWAYS have 2 gallons to "limp home on " when you hit empty..and hopefully won't ever run dry.

Lastly, when done get some Silly~Cone and Seal the WHOLE pot up..front , sides, top bottom and KNOB (so it won't turn ) and so it won't get water inside the pot..and your done!

Doc
04-05-2007 06:20 PM
goshawks00 ok now how much resistor do i need? do you get a bunch of 10 ohm resistors and just start adding them until it reads half full? Can a potentiator be added and turned until they equalize?
Barry
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