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Need some advice with gauges

6K views 39 replies 8 participants last post by  Oilyrascal 
#1 ·
Looking for some advice on what I may encounter with my plan and here it is, pictures below are the gauges
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out of a mid eighties F-whatever pick-up,
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and here is my wiring schematic
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for the harness I installed in the truck.....

I am electrically dumb but it appears that there are no other outside relays gadgets or gizmos that I need to make these gauges work?

It appears after reading about wire # 35 that all I need to do is jump off of that single wire down to the positive side of the gauges and then run whatever sensor wire I have coming from the engine/fuel tank to the other side of the gauge.......

I know it just can be this simple!! Am I wrong?

I will be fabricating these gauges into an existing 52 faceplate ( I hope ) and just need some advice on what I am missing.

Also how do I tell which of the terminals on the rear of these gauges is positive, I am thinking that it does not matter, am I right.

One other question, I still will be using ( trying until you tell me otherwise ) my original 52 fuel tank sending unit, what am I going to run into there......I believe that the sending units are calibrated to the gauges as a matched pair, so does that mean it will not work at all or does that just mean its gonna give me a funky reading in which I will just have to get accustomed to over time but can learn to recognize and fill the tank accordingly.

Thanks again guys for all of your help!!
 
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#2 ·
If the gas gauge is the exact one for the sending unit in the vehicle, then it should be properly calibrated for the gauge. Most sending units operate on OHMs and every make has a different OHM reading for the gauges.
The best advice I can give you is to install a ground block. Ground the block to the frame and then run all your rounds to that block.
 
#7 · (Edited)
voltage control

I forget what it was caused but a lot of Fords used that little box on the back of the cluster about and inch and a half long, 1/2 wide with2 wire stud terminals ? UPDATE... it's called a constant voltage unit. you might have to wire one in if your donor cluster had one.. For Wiring Fords before the computer digital units I use early Mustang wiring diagrams. Google Hammar mustang wiring diagrams, I don't know how to give you an easy link.
 
#9 ·
I forget what it was caused but a lot of Fords used that little box on the back of the cluster about and inch and a half long, 1/2 wide with2 wire stud terminals ? UPDATE... it's called a constant voltage unit. you might have to wire one in if your donor cluster had one.. For Wiring Fords before the computer digital units I use early Mustang wiring diagrams. Google Hammar mustang wiring diagrams, I don't know how to give you an easy link.
Drats, the back of the gauges did have a small box maybe 1 inch by 1/2 inch, stupid thing did not have any studs though but was instead wired into the sheet of ( what do you call it ) .......that electrical tape stuff with all the circuits running through it.

I will have to look into this further, thanks
 
#11 ·
An interesting thing about Ford gages that comes second hand. They are set to read what you may think is good regardless of the actual reading. For example the oil pressure gage may read mid range most of the time with it going slightly higher at higher rpm. In actualality it should read quite low at idle and progressively higher up to a max at some rpm. All that is required is an actual pressure greater than about 5-7 psi at idle to keep a code off or a light off and for the computer to continue to operate the motor. So in effect the gage was nothing better than an idiot light with a pointer.

This was well known with the Supercoupe cars beginning in '99. I had one and found this first hand after seeing a note regarding it. In fact there was an electrical fix that someone came up with that changed the way the gage read so it was more accurate.
 
#12 ·
Interesting info guys, looks like you guys are or at least should be writing the books of facts.

To clear or up simplify things for me I will ask this, here is what I am doing just for clarification.

I have a 1970 W and I plan to use a set of 1986 Ford 351 W water and temp sensor, I do believe that they originally went in the same place on the block and intake manifold and it should be a direct exchange.

I plan to match these sensors up with a set of gauges, water temp, oil pressure, amp and fuel tank with gauges from the same 1986 F-150.

I see on the reverse side of all of these ( approx ) 81-86 gauges a small aluminum box that is hardwired ( for lack of a better term ) into the printed circuit tape. I am assuming this may be the box that you guys are referring to.

I do not ( unless I am missing something still ) know much about messing around with Ohms or measuring any sort of electrical impulses so I am assuming that if I get all of the original items back in the line and within the correct order I should not have too?

All of these gauges have two prongs coming off the rear, one for the power and one for the feed from the sensor.

Any idea on which wire and which gauge has to have this little box included within its system so that everything works properly?

I will need to figure out how the heck to use this little box since as mentioned it does not have any sort of prongs to attach anything too.

Thanks for the clarification, I am VERY close to finally driving this thing and these gauges are a big part of that.
 
#13 ·
The gauges will work correctly matched to their original senders, that much you can count on. Well, as long as they're in working order.

As for the voltage regulator (VR), what I'm seeing (you got me curious so I did some digging;)) is the VR drops the current to 5VDC to the gauges. Some are made to give 12 VDC for a brief time then switch to 5 V. This is supposedly to get the gauges to move quicker towards the correct reading.

I found a thread/post that gives an outline of how to build a voltage regulator for <$10 from readily available Radio Shack parts.
Another page w/photos and a clipped-off-at-the-top wiring diagram:mad: (also shown below): 1972 Ford F250 4x2 - Dash Cluster 5volt regulator

If that's not happening, you can get a VR for an earlier model Ford car or truck, pre-printed circuit era. These VR's have regular terminals to attach wires to. Might want to look one up from a junkyard, though. The VR (Motorcraft p/n GR508) cost $85- in 2008!

If you can solder, there's also a chance the VR you have can be reattached by soldering wires to the connection points it used for the printed board. This is what I would do, personally.



Good luck.
 
#14 ·
The gauges will work correctly matched to their original senders, that much you can count on. Well, as long as they're in working order.

As for the voltage regulator (VR), what I'm seeing (you got me curious so I did some digging;)) is the VR drops the current to 5VDC to the gauges. Some are made to give 12 VDC for a brief time then switch to 5 V. This is supposedly to get the gauges to move quicker towards the correct reading.

I found a thread/post that gives an outline of how to build a voltage regulator for <$10 from readily available Radio Shack parts.
Another page w/photos and a clipped-off-at-the-top wiring diagram:mad: (also shown below): 1972 Ford F250 4x2 - Dash Cluster 5volt regulator

If that's not happening, you can get a VR for an earlier model Ford car or truck, pre-printed circuit era. These VR's have regular terminals to attach wires to. Might want to look one up from a junkyard, though. The VR (Motorcraft p/n GR508) cost $85- in 2008!

If you can solder, there's also a chance the VR you have can be reattached by soldering wires to the connection points it used for the printed board. This is what I would do, personally.



Good luck.
This is what I plan to do as well, have you seen though which gauges need to be in this loop, there are 4 gauges, oil, temp, alt, and fuel, I have read somewhere that only 3 need to have this CVR added to the equation but it did not say which three.

I also still do not know on what side this CVR needs to be on, is it the sensor side or the hot side ( or batter ) Thanks for the digging, it really takes someone that is electrically intuitive to be able to sift thru all of the non pertaining matter.

I guess the CVR itself needs to be grounded??? I am just guessing trying to come up with a plan for mounting it, maybe it needs no ground since it is enclosed in that small aluminum case and mounts to a plastic panel originally. Just guessing
 
#19 ·
more info

I couldn't find my truck shop manual I had for my old and sold 86 truck. I read your questions and info on the ford truck enth. forums. My 2 cents worth, The 66 Mustang CVU has to be grounded, I don't know about the truck one. The power flow on a Mustang is a feed wire from the ACC terminal on the key switch to the 3 gauges, An ammeter or Battery voltage meter does not get that wire feed. And I don't have My old instruction manual From Factory Five for the Cobra Kit car using 80's mustang parts. One of the options was to use the stock Mustang gauges like you are doing in the Cobra instrument panel . and wire them instead of Buying the Smith Gauges (a few more dollors.) The FF cobra instructions also told how to use radio shack led's for panel lights. Years ago I used some Ford truck gages in my willys but was able to use the stock willys cluster and willys light sockets with 12 V bulbs.
 
#21 ·
I do think timothale has it right. All the gauges rely on a sensor, except the ammeter/voltmeter. Establishing a constant, steady voltage for power makes sense here. What the ammeter/voltmeter does is REPORT the lack of stability.

PatM
 
#24 · (Edited)
mustang wiring.

Back in the old days the elect tech-repairman did not use those parallel line diagrams in the factory . We had large blow ups of the ones on the Hammer website. there is a link for the wiki colbalt327 posted above. or google hammar mustang wiring diagrams. both the Hammer pictorial shows a black groung wire to the CVU and down the page, the schematic shows the CVU grounded. Those parallel line diagrams made it possible for the draftsman to get everything on one page, I reduced the labor required to build a wiring harness 30 % by building harness per the print , then laying out the harness so it looked like a tree on a tilted sheet of plywood, it made routing the various wires a lot faster and final installation of the harness was easier.
 
#25 ·
Back in the old days the elect tech-repairman did not use those parallel line diagrams in the factory . We had large blow ups of the ones on the Hammer website. there is a link for the wiki colbalt327 posted above. or google hammar mustang wiring diagrams. both the Hammer pictorial shows a black groung wire to the CVU an down the page the schematic shows the CVU grounded.
http://hammar.dyndns.org/~djhamma/wiring/1965/1965g.jpg shows no ground, just wires in and out. I suppose it could be said to be grounded by the attachment bracket, but my point is it need not be grounded to lower the current from 12 vdc to 5 vdc. If it did, there would be the symbol for a ground.
 
#31 · (Edited)
part no's

Sometimes a running change would result in a recall of sold units, other times it was rework all the units not delivered to a dealer, other times just a service bulletin. There could be idenical parts except for the finish, S2 suffex were black parts, S 36 were the gold colored, the same part out of the die before the finish. , less rust in the salt spray tests. The parts were used elsewhere that were not grounded. We had couple guys that just coordinated engineering changes, find a place to use surplus parts, and there was always a problem in the San Jose Calif assembly plant, . In the winter trains and trucks would get delayed because of the snow storms, and the resident design engineer scrambled to find pieces that would work to keep the assembly lines working. If you have ever had an older ford pickup , trying to find the right combinations of engine bolt on parts can be a nightmare. engines came to the assembly plant with carb, fuel pump and distributor. all the bolt on parts were added per the order, eg, Ac, PS, alt size. emission calibration.
 
#32 · (Edited)
All interesting stuff guys, not to change the subject bUUUt :)

I need to approach this differently I guess, I guess I need to ask a few questions at a time cause Its getting confusing.

I went to the salvage yard the other day and dropped 2 gas tanks and retrieved their sending units. I could not figure out why the heck I could get no reading so that is when I started this post, didnt get much of a response on how to use the meter so I just went ahead and assumed I needed to work harder.

I went to a different salvage yard this A.M and pulled 4 fuel tanks and their senders, I brought my meter with me, none of them read the way I thought they were supposed too. I was sure I just had no idea what to do with the meter.

I brought the meter back to Tampa Napa and asked for a sending unit for an 82 F-150, tested it there, same thing, no results, no-one at Napa had a clue how to use the multi-meter or they just couldnt be bothered to help.

Guy told me save receipt, dont install it, bring sending unit home and try to figure it out with help from your friends on-line.

Did that, came home, tried it again and now its working, also 1 out of the 4 I picked up at Cophers this A.M is working as well. I dont know why they did not work before and at this point do not care.

I see now how the reading goes from high to low, low to high.

I am assuming at this point that since the gauges appear identical from ( I think 81-86 ) Ford trucks that they all carry the same resistance values throughout the system, would you guys agree? I know in 87 they went to a fancier gauge, dash changed ect.

My question is looking at the pictures below........I want to go slow here and learn something, I would like to do what this fella is doing here on this You-tube video ........

Sorry if this has already been answered but which side of this gauge does the hot lead from the battery go on, seems to me it would matter.

Big Cliff seems to think it will and I agree, guys on Ford Forum say it does not matter I believe.

Looking at the video it looks like hot lead from battery goes on one prong of the gauge, then a lead from other side of gauge goes to fuel tank sending unit and then I would ground the fuel tank sending unit to negative side of battery, is that correct.

This guy mentions buzzer box, I dont know what that is and dont think I need to worry about it here?






Thanks guys
 
#35 ·
It will seem as if I am leaving out bits and pieces here maybe but that is because I am finding out ( I am not overly computer savvy ) that many of my questions have been already answered within this thread and I did not realize that they were answered because I did not see that if I clicked on that one particular word that was highlighted it led me to a whole different forum where same questions have been asked and already answered.

Anyway Ok I DO need a CVR and this is it
I am going to ground it I guess, as was mentioned it cannot hurt any.

If I am understanding correctly I need this CVR for all gauges except the Alt gauge, sound right ?

I see big Cliffs explanation of how the power needs to flow thru the gauges.........It will make a difference witch wire is on the positive see if one post has a plus or minis or one is gold and one silver or look at the bottom of the gauge way the needle will move the way the currant will flow to make the needle move,............as a good explanation and makes sense to me and so I will look at it this way.

I have a question though on grounding, Pat mentions grounding the gauges, the way I have the gauges set up within my 52 instrument cluster there is no provision for ground, so I need clarification on how to ground these.

Is it safe to assume that the gauges are grounded thru their metal case so all I need to do is run a jumper wire from case to case and then to a known good ground?

I am still working on my fuel tank sending issues but I am curious, how is the sending unit grounded, is it grounded as soon as its bolted to the tank, I ask because alot of these tanks seem to sit on rubber cushions so that has me confused. Thanks again guys, I am amazed at how much I have learned in such a short time thru this and one other forum.
 
#38 ·
other type gauges

On some gauges there is a light socket included, on those when installing the gauges in a wood or fiberglass dash panel a ground would have to be added for the light. and I like to run extra grounds to everything. Poor grounds that are supposed to be thru the case can cause funny things to happen
 
#39 ·
snap on CVR

The older Mustang style CVR with the threaded studs might be easier to use than the snaps, but you could solder some wires or scrounge the connectors from something that requires a 9 V , battery if they are the same size. Is the copper colored piece on your CVR actually a ground connection. The other colored dots are probably verification quality controll marks for elect test good, mechanical crimps, etc. When I was working in the electronics industry we used to use hot melt glue to secure larger components to circuit boards, just the soldered wire leads would not hold in a vibration- drop test.
 
#40 ·
The older Mustang style CVR with the threaded studs might be easier to use than the snaps, but you could solder some wires or scrounge the connectors from something that requires a 9 V , battery if they are the same size. Is the copper colored piece on your CVR actually a ground connection. The other colored dots are probably verification quality controll marks for elect test good, mechanical crimps, etc. When I was working in the electronics industry we used to use hot melt glue to secure larger components to circuit boards, just the soldered wire leads would not hold in a vibration- drop test.
Hello, thanks fo responding, you would enjoy this thread better than I ICVR Thoughts & Observations - Ford Truck Enthusiasts Forums I think you are following my threads over there and what I have learned in the past week or so on this internet would have possibly taken me years to learn the old fashioned way but this thread gets waay to technical for me.

I still do not know what the I stands for when they reference ICVR?

I do not know what the copper colored deal is but thanks for pointing it out to me, it has given the the chance to look at it and I do believe now it is, regardless I planned to ground the unit just cause I have more faith in what others have told me than the bits I know.

I still would be interested in learning though how the heck this thing is originally grounded, it is screwed into the back of a plastic instrument cluster, I asked this and this is the response I received .......... If you look closely you will see that the later one mounts to the plastic through a bare place on the printed circuit. The older ones grounded through the metal shell of the instrument panel............I have no idea what he is meaning here and I dont want to continue pushing the question because everyone thinks differently and it may be taken as Im second guessing or something so not worth it.
 
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