How To Troubleshoot Faulty Gauges in your Classic Car

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How To Troubleshoot Faulty Gauges in your Classic Car
How do I fix my temp, fuel or pressure gauges in my classic car? How do I even know that they are broken?!? Watch this video and I will walk you through the steps to, not only isolating the problem, but fixing it!

[@JeffLifeInReview]

I’m not a Mustang guy but this was a good explanation that any guy can follow. I learned a lot.

[@CartoonDrawingStudio]

This was very helpful thanks so much!!!! I tested and ordering a new oil pressure sending unit now. Thank you

[@mundrubjet]

Very good, step by step troubleshooting tip. Thanks so much, off to the garage I go...

[@vermbird8393]

sending unit works perfectly. checked resistance with ohm meter. goes from 9 ohms when arm moved to "full" then to 74 ohms when moved to"empty."took out fuel/temp gauge, stuck at midpoint. have photos

[@vermbird8393]

yes the needle is sticking in the middle with the key off. will do the resistance check on the sending unit and then pull the gauge and see if its sticking or what. thanks for your very prompt reply.

[@MustangRestorationsInc]

Try tapping on the gauge lens to see if the needle will unstick.

[@andyguy5764]

Really nice video.

[@filitamayo3786]

what if you ground your temp gauge wire and your temp gauge jumps around. also after reconnecting wire to sender it doesn't move at all. it was stuck on hot side and after grounding to test gauge it jumped around and then got stuck on cold side. when I have it hooked up to sender, and I turn ignition on it did move a lil but not anymore.

[@mikebirch6028]

My Builder installed dual electric fans each on its own 30 amp relay, One is on a manual switch the other on a Temp sending relay, If I have the Manual switch turned on the manual fan works fine by itself, BUT when Temp gets Hot and the Temp Fan kicks on Both Fans will shut off, Then if I turn manual switch off Temp Fan will come back on, I am baffled But obviously No electrician what do You think could be wrong? Incorrect wiring? Thanks so much for what You do I am a Huge Fan Now! Mike

[@MustangRestorationsInc]

First off .. The guy you have doing your electrical work does not apparently know what he is doing. Secondly... The fan fix is to put on a mechanical six blade fan with a shroud & throw the electric fan stuff in the garbage. The electric fans are nothing but problems..

[@elvisjakeforajido8332]

Thanks for the video Chris, very eloquent and instructive. I have a 67 mustang that is giving me problems with the fuel level indication. I have replaced the sending unit twice already because the gauge shows as if there is no petro left. Every time I replace it the level in the gauge is fine/accurate but after a couple of weeks it starts to show an abnormal progressive decline in fuel level in the gauge. When I refill the tank the level in the gauge goes to the maximum as expected but then it drops faster than it should. The first time I replaced the sending unit I thought the floater was defective. With the second replacement i had the same issues and noticed a bit of oscillation in the level. If the floater would be defective the level in the gauge would not be restored after filling up, so there may be something else causing this problem? Thanks in advance for any advice.

[@johnmcclelland6872]

I have the same issue. I am not able to find anything on what could be the cause. Have you found out what was causing your problem. I have gone through two sending units in fear that they were bent incorrectly. I just replaced my constant voltage regulator with no change. The only thing I didn't replace is the gage itself and the wiring. I have verified the 4 to 71 ohms. I have even removed my sending unit testing it to the gage and that appears to have solid resistance. I just don't know if the float is where it should be for the readings I get.

[@miami_aerial_imaging6202]

Hey Doc, hope all is well! Running into an issue with my 70 Mach. I updated a new circuit board and voltage reg on my cluster. When I put the connector back in, the purple wire gets super hot and none of th gauges work. I took 4 AA’s together and was able to check gauges that way, out of the car. Please help!!!

[@MustangRestorationsInc]

It will only move if it senses an Amp issue, but most charging systems get Volt issues

[@donaldfischer1428]

Chris Ingrassia how do you check your amp gauge. The only one of the 4 you didn't talk about?

[@ritchienoodles]

Great video! Definitely taught me a lot. Quick question. Both my temp and oil gauge are stuck to the max level even when the ignition is off. Does that mean the gauge is no good? Thanks!

[@MustangRestorationsInc]

Hi, I would disconnect the wires that lead to the oil sender unit & the Temperature sender. If the gauges now do not come up, then the issue is most likely the sending units being bad or the wrong type.

[@ritchienoodles]

Chris Ingrassia i'll try that. Thanks and have a great day!

[@jrivera500]

what happen if both temp and fuel needles are on the up position and does not go down. 1962 ford tbird. thank you.

[@mikebirch6028]

Hi Chris I have a 1968 Torino, everything is Brand new except a few things like the Cluster, My Builder did not utilize the pulse relay and wired 12 volts directly to the brand new sending unit from the Gauge, The Gauge will read 3/4 tank full with ignition on but there is no fuel in the tank, I ordered a New Pulse relay from Autokrafters and Have the dash apart, am I doing anything wrong here? I will follow Your video step by step and I really appreciate That You have made this one, please Update me if You do not mind! Mike.

[@MustangRestorationsInc]

Hi Mike. Use the original voltage limiter if you still have it.

[@mikebirch6028]

@@MustangRestorationsInc Thanks Doc!!!!!!!

[@mikebirch6028]

@@MustangRestorationsInc I have another question I will post above!

[@waynepetty6372]

Great help. Thanh you !

[@MustangRestorationsInc]

Yes

[@te69penene]

on this mustag the oil light in on all the times and the voltage should go on voltage regulator?

[@stangtcodet4264]

polarity it moved in opposite direction fully but when its back in the car it sits in the middle of D & C @ idle or motor being revved. what could it be ? all other gauges work as they should .thanx

[@jamesleague4816]

WHEN CONVERTING A SWEEP STYLE GAUGE SETUP TO THE 5 CLUSTER GAUGES STYLE IS IT OK TO SPLICE A WIRE TO THE DOUBLE GREEN AND BLACK WIRE COMING OFF OF THE CVU AS IT ONLY HAD TWO COMING OFF FOR THE SWEEP STYLE

[@MustangRestorationsInc]

Yes

[@jadedragon3274]

Hi Chris, i have a 1970 ford f100 with a 360 engine. my temperature gauge isn't working and i replaced the sending unit and the gauge still didn't work, i also grounded the wire (gauge still didn't work). Then i check for the pulsing with a test light and found that there was no pulsing, but all of my other gauges worked fine, any ideas? bad circuit board? bad gauge?

[@MustangRestorationsInc]

Hi..For the gas gauge to work. The limiter must be pulsing or that gas would not be working as you say.Disconnect the wires one by one on the back of the gas & Temp gauges coming from the limiter to check for pulse current going to them & see what you get.

[@jadedragon3274]

Thank you very much for the help and replying fast. I will try this and see if it works.

[@vermbird8393]

on my 63 t bird. fuel gauge does not go to empty when key is off. stays in middle. goes up to about 3/4 full with key on ( has about 9-10 gallons of gas in tank. when i ground the wire to the sendng unit the gauge goes to full. is this the sending unit or the gauge? thanks. i guess man issue is why the gauge doesn't go to empty when the key is off. shall i pull the sending unit our and inspect it and do a resistance test on it

[@MustangRestorationsInc]

Hi. Is the needle in the middle with the key off? If so then the gauge needle is sticking.You may need a new gauge.

[@hugocolmenares4009]

what are you using to ground the temperature gauge?

[@drthunder25]

You think thos same testing would work on my bronco? I temp gauge out and fuel gauge out.

[@mice256]

Hey Doc! My 66 mustang amp gauge is bouncing back and forth at idle. any tips on diagnosing a problem like this? thanks!

[@MustangRestorationsInc]

I would start by replacing the voltage regulator

[@jrivera500]

where can i find a correct voltage regulator 1962 tbird. thanks

[@rickveronick6193]

ok scratchin my head head on this one, fuel gage not working when i got the truck no problem tested sending unit and it was bad got a new one tested with ohm meter before install tests good did a dry test outside of tank before install and when i simulate full tank the gage starts towards full but when it gets to a 1/4 it stops and kinda ticks so i tested the fuel gage by grounding sending unit wire (to tank ground wire) and it goes right up to full, then i installed sending unit as it needed replacing anyway, so each part test good on its own but once installed it will go up to 1/4 tank when key is turned on then creep back down to empty, ant thoughts?

[@MustangRestorationsInc]

Hi Rick. You need another sender.....If the new sender did not make the gauge go up but grounding the wire did...then you have a bad sender.

[@marvinhagler4721]

@@MustangRestorationsInc What about replacing them in a 1970 olds delta 88

[@franciscoechevarria3341]

Tengo 68 mustang y Tengo problems con los gauges .Tengo señal en toto's pero le quito el tester y deja de trabajar

[@khmaisawung]

On my 1984 Chevy s10 truck, the gas read zero and the oil/voltage gauge won't work anymore.

[@roberthowland4503]

I have a problem with my gauges go all the way up and can't seem to find what causes it. can you help?

[@MustangRestorationsInc]

What happened to all of a sudden start doing this?

[@bestcarpetdeals6370]

temperature, oil pressure, and fuel gauge all go to maximum when i start the car i just change the Turn Signal Switch

[@MustangRestorationsInc]

Hi..You may want to call me on this...874-428-9889 7am to 5pm CST

[@westrew63]

I have a 68 Ford Mustang. The fuel gauge stopped working. Then the oil and temp stopped working/. I replaced the voltage regulator on the back of the instrument panel. That did not solve the issue. I check for continuity at the following locations, oil sender unit, temp sender unit and at the fuel sender unit. No power. What do you recommend? Thanks Ron

[@MustangRestorationsInc]

Hi Ron.. I would first put the original Voltage limiter back.. While doing that check for constant current on one post of the limiter with the key in the on position and pulse current on the other pole. That post leads to the three gauges.If you do not have current going to the Limiter with the key on then you have an open circuit leading the it. .If you do have current then follow the instructions in this video.

[@captainpeckerhead4551]

What if you dont have pulse current

[@MustangRestorationsInc]

Call me to discuss.. 847-428-9889

[@vcotta2012]

All of my Guages aren't working

[@michellozier6827]

OIL, FUEL, TEMP. Not working

[@The.2.Minute-Man]

Thanks Chris just picked up a 66 pony coupe your videos are a big help fun to watch and easy to understand ( not rushed ) . Thanks for your time and effort from a happy Aussie..... happy cruising

[@Asukmadik]

wow such a great teacher some people just have that gift thank you nice vid help me out with my 67!!!

[@arcorob]

Hi Chris ! Amp meter question ...All my gauges work (I am doing a restore - 66 Mustang Coupe) except my Amp meter -- it is connected at the dash but for the life of me, not sure what connections I should be looking for under the hood ? IS there a wire that grounds to the voltage regulator ? What wires should I seek out (all the factory wiring is there ) Thanks in advance sir and for the great knowledge you share

[@MustangRestorationsInc]

Hi Bob. The Amp meter measures the flow of current and is wired in series with current flowing in one end and out the other. If you have current at the gauge then replace the gauge. Be aware that an Amp meter does not react like a Volt meter. Meaning that the needle is barely to the right when charging and barely to the left when not. If your meter shows to the right of center then it is most likely a functional meter.

[@reijerlincoln]

Good info, thanks. You Mustang lovers are lucky... the voltage limiter on my '64 Continental is behind the dash cluster but impossible to get to without removing the entire dashboard.

[@arcorob]

Awesome video...can I ask a favor? Show us how to test the current coming to the pulse unit - do you use a test light? And when you say you test the sending unit wires by grounding ...just put one end of a wire to the sending unit wire and the other to ground ? That will make the gauges go UP? Thanks so much

[@randyharris9751]

Doc. Using your process of elimination, I was able to isolate the problem with my temp gauge to a faulty sending unit on my 64.5 Mustang. However, I noticed that the current to the sending unit from the CVR was a constant 5.1 V instead of a pulse current. The original CVR was replaced with a Scott Drake solid state unit a couple of years ago. Comments on some Mustang forums say that a non-pulsing current is the normal behavior for newer solid-state CVRs. What say you? (Thanks for the video!)

[@romephl]

Your very knowledgeable sir.. Happy new year!

[@MustangRestorationsInc]

That is because its a AMP meter and not a Volt meter, meaning Amps flow without fluctuation and you are not going to see any movement in the meter until there is an Ampage problem.

[@rubenarteaga4484]

Thank you, I really needed this information

[@modeljetjuggernaut4864]

great troubleshooting techniques

[@stangtcodet4264]

ok, so thats what the gauge is for ,,basically when everything is operating correctly it dosnt budge,,sits in the middle area but for example if elec system is Overcharging or Discharging then needle will float in that appropiate area Thanks for clarifying that Doc

[@davidkozelsky]

I have 59 chevy apache, my temp gauge isn't working, I did all that and everything seem to be ok, not sure about the sending unit which is brand new from O'reiley's, part number TS-6, maybe it's not compatible with gauge which they say it should be. Any ideas? Thank you!

[@rubenfelix6452]

Very helpful thank you

[@426hemi49]

Gidday.I have an xw gt falcon(Australian car)& the oil,temp & fuel gauges all rise as far as they can as soon as I start the car.what could be the problem.cheers,Chris.

[@MustangRestorationsInc]

+chris hemi Most likely the voltage limiter behind the instrument cluster

[@426hemi49]

+Chris “The Doc” Ingrassia Thanks for the promt reply Chris.I'll check it out.

[@roberthowland4503]

Wow thanks a lot. I got mine in a basket that was great

[@miami_aerial_imaging6202]

Hi Chris, I have 12v constant current going into the new voltage regulator but when I use the same tool you are using with the light on the other side of the regulator, I have nothing, light doesn't turn on. Am i doing something wrong? If there is constant into the regulator, then there should be something on other end. So frustrated! Please help Doc!

[@MustangRestorationsInc]

Ok.. It sounds like your doing it right... As long as the limiter is self grounded on the instrument housing. I am sure you have it fastened to the back of the gauge cluster. The flow of current goes in one tab & like a turn signal light.. pulse current going out the other tab. If you have nohing coming out... then the Limiter is bad.

[@247thericker]

70 mustang Fuel Gauge Issue- I replaced the sending unit. It was rusted over an the float was missing. Fuel gauge still not working. When I tested the connection I got a dim light but not a pulsing light. I also grounded and tested the connection to see if the gauge would move and it did. Is there a bad pulse current or wiring?

[@247thericker]

All of my other gauges work.

[@MustangRestorationsInc]

Yes. I would replace the voltage limiter. Try and find a good used one. talk to the guys at Kentucky Mustang parts. Tell them you talked to me.

[@djbatman77]

I just a 1976 Dodge Charger and none of the gauges work, could the voltage regulator be bad or not working at all? they used to work.

[@MustangRestorationsInc]

Yes.. I believe the Chrysler product use a similar system...

[@Johnshaft1970]

I have a 1970 Ford F250 Camper Special with a 360FE, and i have ZERO readings on my dash gouges. The Oil / Water / Fuel / Alternator Gauges aren't moving at all. This year was the only year that they had a complete metal dash. I checked the fuses and changed the instrument cluster voltage regulator but it didn't change anything ..... any experience with this ??????

[@MustangRestorationsInc]

Hi. I would check to see if you have current going into the limiter.

[@Johnshaft1970]

Chris Ingrassia thank you .... so I need to make sure that i have power to my voltage regulator. And if i don't then I'll have to chase a wire to the battery which is its power source correct ????? I also replied on a different video you had concerning my same issue, so please ignore that one 😅😅😅😅😅😅

[@MustangRestorationsInc]

Yes, You need voltage going into the limiter. Not from the battery, from the ignition switch.

[@Johnshaft1970]

Chris Ingrassia so i need to check my wire connection from the ignition to the back of the instrument cluster, can you tell me what color that wire is that would be delivering power from the ignition switch to the voltage regulator ? Wiring is something I've never tackled so i appreciate your time.

[@MustangRestorationsInc]

Hi John...You will need a "Test light" & the knowledge/understanding to use one.. If you don't.... then you need to get the truck to a guy that can work on electrical as you may burn something up...

[@8rokas8]

hello, my oil gauge goes up at ignition. but when i start the car it drops down. i checked have 5 v. in sending unit wire. and checked it with light it doesnt flash its just all the time on. could it be the problem its not pulsing? where to look for a problem. all rest gauges showing good parameters. thanks.

[@MustangRestorationsInc]

It appears you may have a shorted wire coming from the gauge cluster that could be causing your problem.

[@8rokas8]

Chris Ingrassia well checked my instrument cluster took the new wire from instrument cluster swich.. and the same have 5 v. but no flashing... what could be wrong? oil presure sender new.. new voltage regulator on instrument cluster.. dont have any idea..

[@MustangRestorationsInc]

What year is the car?.. The pulsation comes out of the Voltage limiter behind the cluster and it supplies the other gauges pulse current.

[@8rokas8]

Chris Ingrassia thanks a lot! had to say sorry to my old Voltage limiter :) the old i think still original is working. 5 v pulsing. it seems old better then new one :) thanks a lot saved me a lot of time :)

[@liddo33]

I have a 64 mustang and replaced the contant current limiter from a pulse to a solid state. Gages dont work. Do i need to replace the limiter to an original pulsating one?

[@MustangRestorationsInc]

Why did you replace the old limiter?

[@liddo33]

it shorted out

[@MustangRestorationsInc]

With a test light.. check to see if you have voltage going into the limiter you installed. if so. then put on an original style limiter back on & see where that gets you... if not then you need to find where the break is in the wire that carry's current to the limiter is...

[@liddo33]

ok thank you

[@josea.cacicedo6918]

good morning I have a 1965 mustang and the lights on the dash on and the ones under the dash do not work?

[@MustangRestorationsInc]

Hi. You kinda have a big issue here. Best advice is for you to get the car to someone with some electrical knowledge.

[@elvisjakeforajido8332]

there is a dedicated fuse for the lights in the dash (in my 1967 is called instrument lights), It's a very short 2.5 amps glass fuse. Of course there may be a reason it has blown up but you can start by replacing it.

[@charleq4032]

what if the current is constant not pulsing?My temp gauge is not working.Fuel gauge is pegging past full

[@MustangRestorationsInc]

The voltage limiter may be fused & causing constant current going out of it. Pull the out wire off the limiter and see if the current coming out of the limiter is pulsing. If not..replace it..

[@charleq4032]

the wire on the voltage limiter is constant.There is no wire on the other side.It is pulsing.when i check it with a meter.so i am assuming there should be a wire coming off the side to the other side of gauges?

[@MustangRestorationsInc]

Yes.. The wire your looking for to attach goes to the Gas, oil & temp gauges