Tach and gauges install and wiring done.

[tashakes]

Bought my 73 Vert last month. The gauges were there but not connected. And had the ***** lights on the left dash gauge. I sent the ***** lights and ammeter to RCCI for modification (shoutout to @TheRktmn for the quick service and impecable work!). I also connected the gauges and tach using an 8 and 4 pin computer connectors so they can be rashly removed. While I was there I replaced the steering wheel with the one I got from @PoFoMoCo (thanks for the super quick shipping and careful packaging. For powering the gauges I am using a 12 to 6v converter off Amazon. Looks like it is all working great!

 

[tashakes]

Meh. Spoke too soon. Fuel gauge was working before I started this today and now it only shows 1/8 tank. I know the tank is full because I filled it yesterday. Before I start tearing into it, any tips?

 

[adrian.egry]

I’m just looking at this now as I want to do something similar. I’ve got some connectors and some bulb sockets. I am unsure on the voltage regulator you are using. I have seen new voltage regulator for 69-73 cluster is 5v. Then I have seen on other threads here 5.5v. Then you were using 6v. If the original voltage regulator dies it supplies 12v and the gauges Will constantly read full. It could be your voltage regulator is not supplying enough power (volts?). No expert but that’s where I would start looking maybe?
Can anyone confirm correct voltage for the cluster regulator?

 

[tashakes]

@adrian.egry take a look at this great article. I based my install on it.
'Gauges 101'
https://7173mustangs.com/threads/gauges-101.40104/

 

[71fast]

I’m just looking at this now as I want to do something similar. I’ve got some connectors and some bulb sockets. I am unsure on the voltage regulator you are using. I have seen new voltage regulator for 69-73 cluster is 5v. Then I have seen on other threads here 5.5v. Then you were using 6v. If the original voltage regulator dies it supplies 12v and the gauges Will constantly read full. It could be your voltage regulator is not supplying enough power (volts?). No expert but that’s where I would start looking maybe?
Can anyone confirm correct voltage for the cluster regulator?

I installed this one from NPD and it measures exactly 5 volts.
Not sure if the gauges read right. Seem to be off a little bit and still observing.

https://www.npdlink.com/product/regulator-instrument-voltage-electronic/177875

 

[Steve McMahan]

Have you taken the connector off the sending unit and grounded it to make sure the gauge is sweeping?

 

[tashakes]

Have you taken the connector off the sending unit and grounded it to make sure the gauge is sweeping?

Not yet. My next step is to check the converter to see that it is connected correctly to the back of the dash and that it is putting out 5-6v. Next is to apply low voltage to the gauge to test that it sweeps. My feeling is that it has to do with the converter connection as it was working fine before I took the dash out to install the tach. Thanks for the help.

 

[tashakes]

So the gauge is sweeping. The regulator is showing intermittent voltage from 0 to 5 roughly. I read somewhere that the regulator fluctuates and we need a gauge type multimeter. Not sure about that. But I am ordering a new regulator and see what happens. Odd thing is when I push up on the connector to the gauge cluster the gauge sometimes works to about 1/2 tank. But if I let go it goes down to 1/8. I already cleaned the connectors to see if that helps but no dice, as soon as I let go the gauge goes down. I may need a new circuit card but will start with the regulator and go from there.

Also when I measure the yellow/white wire from the sender I get 77 ohms which tells me it’s working but I don’t know the range it should have. [EDIT] the shop manual indicates 8-12 ohms empty to 60-86 ohms full so mine is working]. I should have about 5/8 tank [so it shows the right impedance].

Thanks.

 

[TheRktmn]

I have found quite a few printed circuit cards that the fingers have come unglued and are misaligned.most likely from the connector being installed/removed at an angle rather than straight.

 

[tashakes]

Thanks @TheRktmn. I believe we may have found the culprit, I am only getting 34 ohms at the gauge post and 77 ohms at the Y-W connector. So I am going to order a new circuit card. With that and the new regulator, I hope it solves the mystery.

 

[adrian.egry]

@adrian.egry take a look at this great article. I based my install on it.
'Gauges 101'
https://7173mustangs.com/threads/gauges-101.40104/

Thank you!

 

[red73mustang]

Bought my 73 Vert last month. The gauges were there but not connected. And had the ***** lights on the left dash gauge. I sent the ***** lights and ammeter to RCCI for modification (shoutout to @TheRktmn for the quick service and impecable work!). I also connected the gauges and tach using an 8 and 4 pin computer connectors so they can be rashly removed. While I was there I replaced the steering wheel with the one I got from @PoFoMoCo (thanks for the super quick shipping and careful packaging. For powering the gauges I am using a 12 to 6v converter off Amazon. Looks like it is all working great!

Dumb question but WHY For powering the gauges do you need a 12 to 6v converter?

 

[tashakes]

They are fed from the IVR. So they work on 5-5.5v. If you feed 12v to them they will fry. Take a look at this article.
Thread 'Gauges 101'
https://7173mustangs.com/threads/gauges-101.40104/

 

[tashakes]

To close out the fuel gauge issue, it turns out that I am an *****. Yes, not the first time, and this just confirms it. I troubleshooted all the wiring all the way back to the sending unit by jumping the connector and the gauge went all the way up to Full. It also turns out that I was reading the impedance wrong, where I thought that ~80 ohms was full and ~10 ohms was empty, and it is exactly the opposite (it is clearly stated in the factory repair manual, but who has time to read....).

The fix, you ask? I ordered a new sending unit (because in my mind that was the issue) and drove the car today to "empty" the tank more and get it ready for replacing the sender. The car stalled and shut off on the freeway, and thankfully was able to coast to the next exit and park. I called my coworker for a can of gas, put in 2 gallons in the tank and it started. Went to the gas station and filled another 16 gallons. And lo and behold, the gauge marked Full. I was sure I had just filled up and the tank was full before embarking in all this fiasco, but it was not, and I ran out of gas. At 59, this is only the second time it happens! LOL. Anyway, lesson learned.

 

[PoFoMoCo]

It’s always an adventure, plus you solved your gas gauge issue so that’s an added bonus!

 

[adrian.egry]

To close out the fuel gauge issue, it turns out that I am an *****. Yes, not the first time, and this just confirms it. I troubleshooted all the wiring all the way back to the sending unit by jumping the connector and the gauge went all the way up to Full. It also turns out that I was reading the impedance wrong, where I thought that ~80 ohms was full and ~10 ohms was empty, and it is exactly the opposite (it is clearly stated in the factory repair manual, but who has time to read....).

The fix, you ask? I ordered a new sending unit (because in my mind that was the issue) and drove the car today to "empty" the tank more and get it ready for replacing the sender. The car stalled and shut off on the freeway, and thankfully was able to coast to the next exit and park. I called my coworker for a can of gas, put in 2 gallons in the tank and it started. Went to the gas station and filled another 16 gallons. And lo and behold, the gauge marked Full. I was sure I had just filled up and the tank was full before embarking in all this fiasco, but it was not, and I ran out of gas. At 59, this is only the second time it happens! LOL. Anyway, lesson learned.

Don’t worry. I did something similiar. Took my car to the car wash and it stalled while idling and I was cleaning the engine. Wouldn’t restart. Lots of cursing later I get the car on to a trailer and bring it home. It had at least 1/2 a tank in it. But the fuel gauge was empty. Turns out it was empty, but it took me a long time to come to that realisation. An expensive and long day.

 

[mrgmhale]

To close out the fuel gauge issue, it turns out that I am an *****. Yes, not the first time, and this just confirms it. I troubleshooted all the wiring all the way back to the sending unit by jumping the connector and the gauge went all the way up to Full. It also turns out that I was reading the impedance wrong, where I thought that ~80 ohms was full and ~10 ohms was empty, and it is exactly the opposite (it is clearly stated in the factory repair manual, but who has time to read....).

The fix, you ask? I ordered a new sending unit (because in my mind that was the issue) and drove the car today to "empty" the tank more and get it ready for replacing the sender. The car stalled and shut off on the freeway, and thankfully was able to coast to the next exit and park. I called my coworker for a can of gas, put in 2 gallons in the tank and it started. Went to the gas station and filled another 16 gallons. And lo and behold, the gauge marked Full. I was sure I had just filled up and the tank was full before embarking in all this fiasco, but it was not, and I ran out of gas. At 59, this is only the second time it happens! LOL. Anyway, lesson learned.

It is never too late to (re)learn lessons, especially from others who dare to share. Thank you for the object lesson. For me, when I have a major "WIN" with a diagnosis (especially one overlooked by others), or repair a particularly complex repair made successfully, I make it a point to not get full of myself." Sure, I will take a victory lap or two, but from there I make a point of sharing with others and not letting a recent success go to my head.

Again, thank you for sharing.

Gil