Does the back of my instrument cluster (IC) look right?

[Steve McMahan]

Still trying to decide on ride height of my front end, but in the meantime, I’m trying to resolve two issues with my dash. Can’t see the gauges in the daytime and my fuel gauge isn’t working.

But before I start, the pics below are my installed IC, after installing my tack upgrade from Rockman. Does it look right?



I ask because I did a dumb thing. I changed two electrical things at one time and now I’m not sure what is wrong. I did the tach upgrade and replaced the fuel sending unit because my fuel gauge wasn’t working. Now, I checked the board voltage unit when I started the process to verify it was working, and it was, so new sending unit from NPD was installed.

I still do not have a working gas gauge and before I pull the IC apart, I was wondering if I’ve somehow installed the Tach upgrade wrong, or left out a fastener connection or something looks missing. BTW, I have idiot gauges and a new circuit board; idiot lights come on when I turn it to run. I’ve checked for voltage at the sending unit and I’ve got nothing. Maybe I’m doing something wrong? Can I test the fuel gauge on the IC? I have a Power Probe.

Since I was gonna put a few LEDs IC lighting bulbs in, not the Alt bulb, I pulled the IC to double check the voltage of the IVR (?).

Thanks.

 

[vintageman]

Steve, I can't help you with the IVR positioning as mine has a hardwire connection from Midlife. I can say that I changed my fuel sending unit in the tank out as well only to find that my fuel gauge itself was bad. Luckily, I had one on hand and that one worked well. Good luck and hope you get it figured out.

Tom

 

[Steve McMahan]

Should I have continunity across the fuel gauge itself! when I put the VOM on it, I get zip. I retested the IVR and it takes like 1 second, and then the meter shows voltage, not constant, but constantly changing, from the 4 to 6 volt range. I took that as a working IVR.

Anyway, the continuity of the gauge itself is my question.

 

[Don C]

Should I have continunity across the fuel gauge itself! when I put the VOM on it, I get zip. I retested the IVR and it takes like 1 second, and then the meter shows voltage, not constant, but constantly changing, from the 4 to 6 volt range. I took that as a working IVR.

Anyway, the continuity of the gauge itself is my question.

You should have a reading of 10 to 14 ohms on the fuel gauge, with an ohmmeter.

 

[Kilgon]

From what I can see the circuit for the gas gauge should work. Don't know about the tach upgrade. If you have can get a 10-ohm resistor you can make a 6v power supply out of 4 aa batteries and you can test the gauge to see if it is working. Put the 10 ohm in line on the negative side. There is no polarity on the gauge itself so touch one lead to one side and the lead with the 10-ohm resistor to the other side. The gauge should show full if it is working. If not, then a bad gauge. If it works then problems lies in wiring or you got a bad new sending unit.

 

[Steve McMahan]

Ok, so long story, I checked and I had no continuity, no ohms at all, zero. So, I started to look at replacement gas gauges, nothing at NPS or CJ Pony, but a few new NOS, and a couple used on EBay.

And not cheep i may add. So, since I had nothing to lose, I removed the gauge, and opened it up. As suspected, a nichrome-type, bend a moment arm, type gauge. Only one problem, one of the leads had broken free of the epoxy at the top of the bolt. So, I went through all of my expoxies and none said they would conduct electricity, so, I ground off that material, and since I had a bit of lead wire, I wrap it around the bolt (the side that goes to the sending unit, and tested it. It worked, so I put the gauge back in the IC, with my new LED bulbs (I tested them because they only go in one way and work), skipped the turn signal, idiot lights, and Alt bulb, and put the IC back in, and what do you know, my gas gauge works. And it appears to be close as well.

I‘m sure what I did changed the resistance of the gauge, and my readings will be off by some amount, but beats no gauge. And, I can see the instruments.

 

[Vern Cook]

My experience has shown me that gauges can be fine wired, fragile and well above my pay grade. I took mine to a professional down the road and it didn't cost that much.
Whatever you do, hope it works out for you.
Vern

 

[vintageman]

Ok, so long story, I checked and I had no continuity, no ohms at all, zero. So, I started to look at replacement gas gauges, nothing at NPS or CJ Pony, but a few new NOS, and a couple used on EBay.

And not cheep i may add. So, since I had nothing to lose, I removed the gauge, and opened it up. As suspected, a nichrome-type, bend a moment arm, type gauge. Only one problem, one of the leads had broken free of the epoxy at the top of the bolt. So, I went through all of my expoxies and none said they would conduct electricity, so, I ground off that material, and since I had a bit of lead wire, I wrap it around the bolt (the side that goes to the sending unit, and tested it. It worked, so I put the gauge back in the IC, with my new LED bulbs (I tested them because they only go in one way and work), skipped the turn signal, idiot lights, and Alt bulb, and put the IC back in, and what do you know, my gas gauge works. And it appears to be close as well.

I‘m sure what I did changed the resistance of the gauge, and my readings will be off by some amount, but beats no gauge. And, I can see the instruments.

Great job Steve, I may do the same for my old non-working one as well. Thanks for the update.

Tom

 

[Steve McMahan]

Yea, I know I should find someone to fix it right, but I’m a long way from a perfect car. I just wanted something that was greater than zero; it appears to be about right on the fuel level.

Whats more interesting to me is, the cost verses complexity issue for parts on this car. On another mustang forum, I had a bit of a rant over Holley’s new in tank fuel pump that use the stock driver side fuel outlet. If you look carefully at the part (It looks like a Scott Drake unit), it looks exactly like their stock sending unit (a Scott Drake unit) with a $39 pump attached to it (Spectrum Fuel Pump with same specs). Adding that pump increased the price of the unit from $49 to $429. I’m not trying to beat up on Holley or any one manufacture, I’m just saying that many times the development and complexity of the item being sold has no resemblance to the price. It’s back to what can I get? I just think we, as the market for these products, must push back on these outrageous offerings, telling them we will not buy from them.

In case you’re wondering, I have similar concerns on some of the gauge prices. Rant complete.

 

[Mark Jones]

I am right with you on parts pricing Steve. I have the same gripe. For example, Rock Auto sells a replacement 90 degree terminal and wire for the Temp gauge for $1.62 to $9.99 but the same wire and connector for the oil temp sender is $36 to $42. The threaded terminal on the Temp sender and the Oil sender are the same size. Maybe I am wrong but I bought (2) of the cheaper terminals and used them for both the temp and oil sender. I guess that why "Cla$$ic" is spelled with two $$'s. Not for the faint of heart for sure.