[grabberbluemach]

My gauges on my 1970 mach 1 have stopped working! The car was recently re-wired and the old circuit board was replaced with a new one. I checked the circuit board to make sure it wasnt melted or anything and I checked the fuses, everything looks fine. The only gauges that work are my Speedometer ( obviously ), and my battery meter. Can somebody please help me figure out why my Fuel, oil, and temp gauges have decided to quit?!?!?!? :?:

 

[dne']

Cvr

HI! :wavey, dne' here! Do a search on this little critter.
Of course always looking for the least possible thing that could go wrong(BE SURE YOUR DASH IS GROUNDED first, ie), I'd have to look closely at your Constant voltage regulator(I'm not familiar with the '70 model, but it's probably mounted behind your dash like my '67)). Please don't be confused and think I mean your Voltage regulator underneath your hood). The CVR maintains proper amount of voltage going to your gauges so as not to melt them! If the points inside the little widgit becomes "old" and pitted, it won't work, thus the gauges won't work. I put an electronic CVR in my '67 Mustang. Of course you need to make sure there is voltage leading up to the CVR, if there is no voltage going to it, then you have to dig more. Do your dash lights work?(I can't remember without looking in my shop manual if the dash lights go through the CVR). That's about all I can offer you without being there.
HOpe this helps abit! Surely someone else will chime in! :bigthumbsup
dne'

 

[grabberbluemach]

Hi, thanks for the reply. My dash was grounded when I tested it but my dash pad was not on ( that shouldnt make a difference ) And im pretty sure the CVR box you're talking about is located just below my fuse block on my mach1. I didnt replace that when I re-wired my car but it was working before the repair. And yes my dash lights do work its like I have 3 dead gauges. What originally happened was my original circuit board melted and I "fixed" it a few years ago, and that lead to my ignition switch frying which prompted my entire underdash wiring system to be replaced ( I really screwed up with this one lol ). After my car was re-wired I put in a new circuit board from CJ Pony Parts but I wasnt paying attention and put my plug in upside down ( cuz I was anxious to drive my car again ) Needless to say that melted a section of my new circuit board. The overall condition of the board was ok but there was one interrupted circuit on it. I looked up in my original 1970 shop manuals what the circuits did and sure enough if there is one interrupted circuit the gauges will not function. So I drove around for a few days without my gauges until I got my new circuit board in. Well I put the new one in ( made sure it was in right ) and still, my gauges do not work. I double checked to make sure there was not an interrupted circuit like the manual had warned and this time everything was fine. So my first reaction after that was to check the fuses and sure enough they're fine too. I will be sure to check the CVR when I get home to see if it looks like it took a hit when my system fried. Lets hope this helps my issue... Thanks again

 

[dne']

you can do it!

I can feel your anxiety over this! I really don't like the electrical portion of these old cars, but it's part of the deal, and to pay someone would probably be costly, but then you(we) don't learn do we!
I don't know how difficult it is to pull your dash, I'd hate to pull mine on my '67. However mine is not permanently installed yet. I thought sure some electrical guru's would chime in, but it's still early in your thread, and surely someone will have a good answer. I guess what throws me is your system being rewired, and only heaven knows what particular wire is not making connection!

If I know me, I'd probably check my constant voltage reg, then if that's OK, then I'd have to put my nose in the manual, then come to a logical conclusion to pull my dash, take my VOM ,or test light and start systematically eliminating stuff~ It will probably be something stupid simple!!! :gringreen
good luck,
I'll be watching this thread to see how you do!:winks
dne'

 

[grabberbluemach]

Its not difficult to pull my dash I just hate doing it... But I re-wired it with a factory harness out of a car with identical options as mine so all the connections and wires are factory. If there is a problem it will be much easier to track it that way instead of having to search through a mess of aftermarket connections. So I think I saved myself there. But im starting to wonder if my new circuit board is bad. Because the problem is still my fuel, oil, and temp gauges and the manual says that is due to an interrupted circuit at the board. So if there was a manufacturing flaw or a hairline fracture in one of the copper circuits it would cause my gauges to malfunction and not work. I might contact CJ Pony Parts and see if they will work with me and give me a new circuit board to test it. I doubt they do it but its worth a try :winks

 

[dne']

printed board

OK, I understand a little better. I found a circuit board from a '70 stang. Is this kind of what you're dealing with? It may not come up very large to view, but again, I'm just trying to understand what you're up against. Looks pretty simple! My '67 just has wires running all over the place behind the dash connecting things together, but I find it easier to work with than perhaps a printed circuit board, but the printed board sure cleans up the back of a dash! Well, I'll be chiming in now and then~ :yup:

 

[grabberbluemach]

Yup, thats exactly like my original one. The originals were thicker than the new ones and the originals were green, the new ones are white and cheap looking... I think I need to find a NOS circuit board because these new ones just look like crap in my opinion. But those copper circuits are EXTREMELY thin and fragile so If there was a small crack in one of them that could cause the gauge failure that im experiencing. But I wont know until I try it... UGH this is killing me so bad... I'v only drivin my car twice in the last year because of all the problems i'v had with it. And what sucks is that I move back to Michigan in a month and I wont be able to take it with me :sadcry I know it sounds like with all the problems I'v had you would expect my car to be a project car, but no.... Its an original car with 74,000 miles on it. I take it to shows when I can, and I always come back with trophies. To my knowledge the motor has never been out of the car since its initial assembly from Ford. So its in amazing physical condition it just has a lot of unexplained problems...

 

[dne']

Why

Somehow, someway, you will remedy this problem! Will going to Michigan be a long term thing~ I mean you will eventually have your Stang back with you? I have to be nosey, but what's the story? why are you moving?
dne'

 

[lxixboss]

Hi there,

I had the same problem with my '69 last year and some people on this forum helped me out. The problem with mine was that one of the gauges (fuel level, oil pressure or water temperature) was shortinig out on the gauge housing. This caused all of the gauges to stop working. You have to make sure that none of the posts coming out of any one of the gauges is touching the metal housing. If your cluster is out of your car, one easy way to test it is to apply voltage (I used a 6-volt dry cell battery) to one of the posts of one of the gauges. Next, attach a test light to the other post of the battery and touch the housing with the test lead. If the light goes on, that gauge is shorting. Loosen the nuts holding the gauge and move it around until the light goes out. Do this for all of the three aforementioned gauges. I'll bet you find that at least one is shorting out.

I hope this helps,
Richard in Ottawa, Canada

 

[grabberbluemach]

I go to school in Michigan, So the next time I will be back In Missouri where my car is will be mid December. And I dont drive my car in the winter so I wont be able to take it out again until next spring or summer. Thats why I am kinda bummed out over this entire situation. I took off the Voltage regulator for my gauges, It was just a small little box thing with two snaps on it that the circuit board attached to. I went to Autozone but they dont have one, so im now looking online to find a replacement.


@ lxixboss- Thanks I'll try this when I get back home, my gauges are out of the car at the moment so it will be easy to test.

 

[grabberbluemach]

Ok so in my search to find a new Gauge cluster voltage regulator I found out that they are kind of expensive for such a small part lol. The cheapest new part I could find was from RockAuto and it was $53 something, But according to their picture the mounting tab on the part is upside down. I called and they said they would have to contact the manufacturer of the part to see whats going on. The next cheapest I could find was $99.99 on ebay for a new one. But the cheapest I could find overall was a used one on Ebay for $25. I dont know about you guys but for something like this I dont know if I would buy a used one. Can some of you guys help me find one? Im including a picture of my old one I removed today. If you notice the tab is pointing downward on mine with the little copper flap on the top side, if you go to RockAuto you can see why im saying that the tabs on theirs are upside down...Sorry the pics are a little blurry I took them with my phone.

 

[ic237]

Ok so in my search to find a new Gauge cluster voltage regulator I found out that they are kind of expensive for such a small part lol. The cheapest new part I could find was from RockAuto and it was $53 something, But according to their picture the mounting tab on the part is upside down. I called and they said they would have to contact the manufacturer of the part to see whats going on. The next cheapest I could find was $99.99 on ebay for a new one. But the cheapest I could find overall was a used one on Ebay for $25. I dont know about you guys but for something like this I dont know if I would buy a used one. Can some of you guys help me find one? Im including a picture of my old one I removed today. If you notice the tab is pointing downward on mine with the little copper flap on the top side, if you go to RockAuto you can see why im saying that the tabs on theirs are upside down...Sorry the pics are a little blurry I took them with my phone.

Ford Mustang Instrument Cluster Voltage Regulator 5v: eBay Motors (item 270589603277 end time Aug-04-10 18:03:32 PDT)

 

[grabberbluemach]

Hey thanks for that link, but im kind of iffy about going to a newer electronic one... I think i would feel better just putting an original style one back on, considering my car is 90% + original... Thanks tho! If i cant find an old style one I will look into this. :bigthumbsup

 

[grabberbluemach]

I found a "New in Box" original CVR for less than the reproductions if you can believe that! Before I bought it I double checked and triple checked to make sure it wasnt something I did to make them not work and I could not find anything. So now that I have my new part on order, all I gotta do is wait. I will be sure to let you guys know if thats what fixed it!!! Thanks for the help, you guys are great! :shiny:

 

[grabberbluemach]

Just got my new part in today! im going to put it on tonight and hope it works!

 

[grabberbluemach]

Bad news... My new Voltage regulator did NOT fix my problem... I have triple checked the fuses and grounds and for the life of me cannot figure out why my gauges are not working

 

[dne']

HI again!

HI!! and RATS! I'm so sorry to hear it wasn't a simple as just replacing the CVR! When you say you have "triple checked the fuses" are you using a test light, or VOM? YOu're going to have to really get technical now(like you haven't already)! Do you have voltage leading up to the CVR, yes/no? Do you have voltage on both sides of your new CVR? I was looking for a schematic to your stang, but found one, but couldn't print it out and wasn't readable on the screen. How can you be sure your dash is absolutely grounded? If there is a ground wire that is visible coming off of the dash, you have to make sure it is absolutely grounding. Take a test wire with alligator clips, clip to the housing~ to ground. I was also looking to see if the CVR has to be grounded itself? Mine is screwed to the metal housing of the instrument housing.

If you have a schematic, get some ice tea, and a good light, trace wires and learn your specific wiring. Just for added thinking, May not even be something wrong with your dash, may be something sneaky like beneath your hood wiring. It's an irritating process of elimination, but you can do it!:winks
dne'

Bad news... My new Voltage regulator did NOT fix my problem... I have triple checked the fuses and grounds and for the life of me cannot figure out why my gauges are not working

 

[grabberbluemach]

Hey thanks again for the input... I'll be sure to try testing the voltage to every single piece when I get the chance, this is driving me crazy lol

 

[dne']

Good plan!

ah grasshopper, one must think like the wiring~ it flows in one direction! OK, good plan! Curious to hear what you come up with!

Hey thanks again for the input... I'll be sure to try testing the voltage to every single piece when I get the chance, this is driving me crazy lol