Trouble shooting Gauges in my 1967 Mustang

Well, the gauges in my Mustang have not worked since I rewired the car with the American Autowire harness kit. It is time to see if I can figure out why. I troubleshoot the oil pressure, fuel, and temp gauges to see if I can figure out why they are not working.
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[@SmackeysGarage]

Nice walk through. That's a lot of wires on those gauges. On the 69, they had a "flexible circuit". It is interesting to see the differences.

[@ellesmerewildwood4858]

If you were in Melbourne Australia I'd be happy to get all those gauges working perfectly for you. I should move to the US and set up, "Ye olde gauge repair shoppe". There seems to be a lot of people on YT having issues with their classic car gauges. The video is over a year old so I suppose you've got the situation sorted by now. Getting the exact right sender is a minefield for these gauges is an absolute minefield most of these replacement parts are made in China. If you don't already know, the gauge resistance for all your gauges is 73 ohms at low and 10 ohms at high. The little device you keep referring to as a relay is a voltage reducer/regulator which drops the voltage from 12 to 5, if it's showing 5.5 it's a little too high. If it's an original thermal type, get rid of it and install a solid state unit and honestly if you're handy with a soldering iron you can build your own super cheap and be extremely reliable, there are plenty of circuits on line. Then check that the gauge windings are still okay. You should be able to look inside the gauge without taking the dial off, if the windings are black, they're burned. The gauge might still work but now very well. If the windings are still okay, like if they;re a light tan color, then the problems are in your senders. Oil sender should be 70-75 ohms with engine off then climb to about 25 ish ohms with engine at idle. Temp will be very high ohms at cold, for some reason they are all different at cold but all very high, in the hundreds of ohms but the thermister resistance changes very quickly once it starts to warm up, engine cool should climb quickly to 70 ish ohms then at operating temp should be around 20-25 ohms. Tank unit should be 73 E, 23 Half, 10 F. If the regulator is holding 5.5 volts, it's high but if the gauges are okay they will just read a little high but the output voltage should not be higher than 5.05 to 5.01. Anyway, if you get yourself a 3 watt 100 ohm wire wound potentiometer from your local electronics parts store, you can use that a a proxy sender to test the gauges. Just mount it on a plate, draw a reasonable 0-100 scale in 10 ohm steps. Lately YT keeps recommending these videos to me but they're all old and I wish I could be more help.

[@67Stang]

Thanks so much for watching and leaving a comment. I ended up replacing them with Dakota Digital Gauges which have been working perfectly. Very happy with them. I still have the old gauge cluster just incase I want to go back. So this is good information to have so I can test them. Thanks again.

[@eGISAssociates]

Great video. I think you are correct that the sending units for each gauge provide variable resistance depending on the temp, pressure, or level. That resistance determines the level indicated on the gauge.

[@67Stang]

Thanks

[@shawnc7808]

Good video very informative

[@TomsBackyardWorkshop]

You can just pull the cluster forward a couple of inches and disconnect the speedometer cable. Its super easy.

[@67Stang]

I tried that but there was not enough play in the speedo cable to get enough room for my hand to get back there to get enough grip on the connecting nut.

[@carnut7436]

Looks like the cat just sprayed on your cars fender in opening of your video. Lol😅

[@67Stang]

Luckily for me, he was fixed so nothing happened.

[@bobsbarnworkshop]

Check continuity on the wires to each sending unit then get a 100ohm resistor at radio shack or a low ohm pot like 1,000 ohms (or under) and connect one end to chassis ground and the center tab to the wire to the gauge. With the gauges powered up vary the position of the pot and the gauge should move

[@67Stang]

Thanks for the information. I already have a replacement set of gauges from Dokata Digital I still need to install but I might test the old ones and keep around if they are good just incase I want to go back to stock.

[@AlanSchildroth]

Was the oil pressure gauge not working because of the tape for leaks?

[@67Stang]

No, I don't think so. I never have been able to get the original guage to work. I do have a mechanical gauge under the hood that works fine. It could be the new sending unit or the gauge itself has gone bad.

[@Meche697]

which was the video with the motor mounts?

[@67Stang]

Don't think I have one about motor mounts. I have not replaced mine.

[@donnyboy9505]

Sounds like the oil pressure gauge..yes if they touch the housing they will not work..there is a Facebook forum for mustang 6 cyl..see if someone has extra gauges lying around..I might even have some….let us know if you fixed them.

[@67Stang]

I have not been able to get them working. The gas guage comes and goes. Only will read 1/2 when completely full. Temp gauge will move ever so slightly. Oil pressure does nothing.

[@donnyboy9505]

@@67Stang ..this is exactly what happened to a friend of mines 67..went through them IVR..like crazy..they say the digital IVR ones are junk…might be worth looking on eBay for a nos IVR…my friend finally quit a got a digital gauge cluster..good luck..

[@67Stang]

@@donnyboy9505 I a leaning toward going with Digital gauges as well. Any recommendations? I have seen several folks go with Dakota but those aren't cheap.

[@donnyboy9505]

They are expensive..that attachment on your oil sending unit…is it metal …if not..such as brass or aluminum…would it not prevent a good ground for the oil gauge…can’t tell in the video what’s it made off…

[@67Stang]

@@donnyboy9505 it is metal and I have verified connectivity with the block

[@classicstangbrn8964]

Ck that crappy solid state cvr.