gauges go to max when key on

[Thunderfoot]

i am sorry . everytime i get on here the past few days some idiot comes in the room adn wont shut the f up. i will keep trying to help but i cant until she shuts up.

I think something with the time of the year (season) has something to do with that.

[fordman]

no

[dwebster8783]

when the gauges are hooked up to the plug that gos into the back of the cluster and I turn they key on and remove the wire from oil and temp senders at engine it does not change they both stay pegged.

it looks like the gauge pod is gronded to the cab so I ran a new wire. old one looks fine but at this point I am starting to get pissed.

so you are saying that I need to space my gauges from the mounting case to keep metal to metal contact from happening?

[Thunderfoot]

when the gauges are hooked up to the plug that gos into the back of the cluster and I turn they key on and remove the wire from oil and temp senders at engine it does not change they both stay pegged.

it looks like the gauge pod is gronded to the cab so I ran a new wire. old one looks fine but at this point I am starting to get pissed.

so you are saying that I need to space my gauges from the mounting case to keep metal to metal contact from happening?

Hang in there we'll get it figured out

Just to confirm the gauge cluster you have is similar to this correct? (Scroll down to the photos of the instrument panels.) http://www.fordification.com/67-72ID.htm it is a 70 so it has the metal back correct?
And you checked continuity from the terminal mounts on the back for the gauges (oil and temp) to the metal housing and they were shorted to the housing then that is the problem. They should be isolated from everything there and only have connection through there circuit paths in the printed circuit film. Maybe the paper isolators there that you seen have gotten moisture and are not isolating them from the housing. You may be able to get some plastic washers at the hardware store to replace them, but those terminals must be isolated from the housing...

I must admit this is strange that this all happened after changing out the tank sending unit, the one shouldn’t have had anything to do with the other… could have been from the change in the weather or the just old stuff...

[fordman]

this one has me thinking hard also. the only thing i keep coming up with is a short of some sort. wires or contacts grounding out wrong.

[dwebster8783]

mine is the 70 with the metal housing back. I am going to try and shim the gauges out some this morning some time. and I will let you know what happens. I just have to get this kids to stop crying all the dang time

[dwebster8783]

ok so this moring I said to my self I was going to get these dang gauges working no matter what. the one problem is I did not want to go to the hardware store to get some washers to space the gauges away from the metal case. I was getting some soda and drank the last of it out of a two litter bottle and thought that bottle would make some great spacers. so I got the utility knfe outand started cutting. put it all back together and installed it in the truck. started the truck and let it warm up. and what do you know it works.

one thing I dont under stand is the ipvr is grounded out to the metal case which will ground the gauges to the case. why is this? I dont understand how what I did made it work because of the ipvr having a connection to the case which in turn will give the guages a dirrcet connect to the case.

Does anybody have an answer to this?

now all I have to do is adjust the ipvr so my fuel gauge reads perfect. I need to make my gauge read about a 1/4 tank more than it does right now. do I turn that set screw to the left or right?

[fordman]

i'm glad that worked. i dont have any answers for you as to how to turn it. but i would like to know why the guages messed up like that. if all you did was change the sending unit. it doesnt make since to me.

[dwebster8783]

I dont have an answer either. I can normally figure stuff out wuick but I will tell you what. this kicked my A$%. I think I am going to spend some time going through every single connection and cleaning or replacing after this ordeal. thanks for all the help guys.

[ezernut9mm]

i am sorry . everytime i get on here the past few days some idiot comes in the room adn wont shut the f up. i will keep trying to help but i cant until she shuts up.

damn, craig. she's gonna kick your a$$ for talking like that.

[Thunderfoot]

one thing I dont under stand is the ipvr is grounded out to the metal case which will ground the gauges to the case. why is this? I dont understand how what I did made it work because of the ipvr having a connection to the case which in turn will give the guages a dirrcet connect to the case.

Does anybody have an answer to this?

Ok hold on there may be a test at the end.

IPVR is a basically a voltage regulator, it needs to be grounded (or have a ground reference) to work. The IPVR supplies this adjusted voltage to the gauges.
The gauges (fuel, temp, and oil) are basically "volt meters" they have power going to one terminal and the other is the ground connection via the (sending unit)
The "sending unit" is a variable resistor that changes with (pressure for the oil), (temp for the temp), and (fuel level for the fuel) this changes the voltage read over the gauge because it is a series circuit.

How the cicuit works;
That is if you put a couple of resistors in line and apply voltage through them it will divide the voltage over each resistor depending on how much resistance they have, but measure the voltage over all of them at once and it equals the total voltage you are supplying.

This is where the IPVR comes in... it is a fine adjustment to the accuracy of the gauge, basically calibrating it to read correctly, because you are changing the voltage it is reading by changing the voltage supplied to the circuit.

That is a short explanation that I hope makes sense.

Ok no test, class dismissed.

Glad you got it working and sounds like it was just a coincidence that this happened when you changed the fuel sender… I hate those, they kick my a$$...

On the set screw, I have never adjusted one so not sure which way does what but my guess would be to turn it to the right.

[dwebster8783]

hey thunderfoot that makes a lot of sense actually. I dont know why this all happened at once but thats my luck. I plan to one simple thing and I end up doing 20 hard things alog with that one simple thing. I will try turning the set screw to the right and see what happens. but right now I have to help clean the house for company. all I want to do is play with my truck mommy!

[Thunderfoot]

Glad that worked out

I know how you feel on the one leading to more... I got the same problem but it's self inflicted. I start out doing one thing and I get the "while I'm there I ought to do this" and if I'm going to do that "I might as well do this".... Then I end up with a completely disassembled vehicle

Have a good one, I'm off to a party myself!