Might have been answered elsewhere...guage questions

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jjdeal79
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Might have been answered elsewhere...guage questions

Post by jjdeal79 »

Yet another gauge question.... So my '72 needs to be put back on the road. Previous owner took out all wiring and installed on of those not so EZWire harnesses. I got the truck dirt cheap, 4 years ago. Got it running again and parked it. You can see why in my signature below.....

So, no original wires for the gauges. Printed circuit board is still there. No connector. If I wire it up like my '68, does this require a resister wire? If so, anyone have a part number or source?

Also, if i get new analog aftermarket gauges, I assume I need new sending units? There is now an undermount gas tank that I do not want to drop.....

As always, thanks!
Last edited by jjdeal79 on Mon May 22, 2017 11:13 pm, edited 1 time in total.
-JJD-
1968 F100 4X4, 360, manual everything, project truck, 4th owner!
1972 F100, 360, C6 was “parts truck", heavily molested before I got it, but it runs great!
2004 Taurus wagon, original owner, 200,000+ and zero major repairs!
2020 F350 6.7 adventure machine
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basketcase0302
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Re: Might have been answered elsewhere....

Post by basketcase0302 »

jjdeal79 wrote:Yet another gauge question.... So my '72 needs to be put back on the road. Previous owner took out all wiring and installed on of those not so EZWire harnesses. I got the truck dirt cheap, 4 years ago. Got it running again and parked it. You can see why in my signature below.....
So, no original wires for the gauges. Printed circuit board is still there. No connector. If I wire it up like my '68, does this require a resister wire? If so, anyone have a part number or source?
Also, if i get new analog aftermarket gauges, I assume I need new sending units? There is now an undermount gas tank that I do not want to drop.....
As always, thanks!
Gonna be no easy answer to this question as there's no way to tell what the PO did with the PAINFUL / EASY wiring harness, (in terms of what he wired and what he left unwired. Each gauge is different so start studying the wiring diagram here and it might help. To start with the instrument panel lighting gets 12 volts from the headlight switch via the resistor there (to brighten or dim) / the volt meter / gauge gets 12 volts from the alternator circuit / and the rest you can find here:
Image

Or here:

http://www.fordification.com/tech/wiring_1972master.htm

And yes your new gas gauge, (try to find the brand model of existing tank you have and match decipher the sending unit) has to match the sending unit in regards to the ohm rating parameters.
So many folks start throwing those painful / ez wiring harness's into our trucks with good intentions and then 90% of the trucks wind up for sale when the guys wind up figuring out they should have just repaired the existing wiring harness in the truck, (which would've also kept the resale value of the truck higher). :wink:
Jeff
http://www.fordification.com/forum/view ... 22&t=46251
SOLD-71 F-350 dually flatbed, 302 / .030 over V-8 with a "baby"C-6, B & M truckshifter, Dana70/4.11 ratio, intermittent wipers, tilt steering, full LED lighting on the flat bed, and no stereo yet (this way I can hear the rattles to diagnose)! SOLD!
Many Ford bumps / one 76' EB / and several dents through the years.
A lot of "oddball" Ford parts collected from working on them for 34 years now!
2008 Ford Escape 4 x 4
jjdeal79
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Re: Might have been answered elsewhere....

Post by jjdeal79 »

I dont know if it's possible, is there a way to test a sensor to get a reading, to match a guage? Resistance? I really dont want to drop the gas tank....
-JJD-
1968 F100 4X4, 360, manual everything, project truck, 4th owner!
1972 F100, 360, C6 was “parts truck", heavily molested before I got it, but it runs great!
2004 Taurus wagon, original owner, 200,000+ and zero major repairs!
2020 F350 6.7 adventure machine
jjdeal79
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Re: Might have been answered elsewhere...guage questions

Post by jjdeal79 »

The original gas tank has a sending unit, but no markings. What was the original sending unit voltage?
I have studied previously posted diagrams.
I will most likely have to pull the old "circuit board" off and wire up like my '68. I will probably have to get a '68 cluster regulator. Anyone see any possible red flags? Of course, this is assuming that all sending units are stock.....
-JJD-
1968 F100 4X4, 360, manual everything, project truck, 4th owner!
1972 F100, 360, C6 was “parts truck", heavily molested before I got it, but it runs great!
2004 Taurus wagon, original owner, 200,000+ and zero major repairs!
2020 F350 6.7 adventure machine
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basketcase0302
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Re: Might have been answered elsewhere...guage questions

Post by basketcase0302 »

jjdeal79 » Mon May 22, 2017 11:19 pm
The original gas tank has a sending unit, but no markings. What was the original sending unit voltage?
I have studied previously posted diagrams.
I will most likely have to pull the old "circuit board" off and wire up like my '68. I will probably have to get a '68 cluster regulator. Anyone see any possible red flags? Of course, this is assuming that all sending units are stock.....
You should be reading 12 volts, (with the ignition switch turned on) at the in cab sending unit center wire.
And yes you can test the original sending unit, (you ohm it out). It will have a variable resistance and I can never remember the exact number of ohm's your measurement will read, (which will always vary anyways as when new it will not read the same as an old sending unit). The sending units in our bumps are known for being the culprit when it comes to the gas gauge.
Highly recommend not attempting to rewire your instrument panel by cutting out the printed circuit wiring harness as you'll more than like start blowing fuses and frying wiring, (it's a whole different story / a piece of cake / re-wiring a non printed circuit board instrument panel). The printed circuit board harness connector is also a known culprit for instrument panel issues. Unhook the battery and pull out the instrument panel and very carefully clean all the copper connections on the harness, (using very small fine bristle hand held copper wire brushes) / clean the copper "ribbon" connections on the back of the panel, (where the harness plugs into) and look very carefully for fine hairline cracks in the ribbon, (keeping in mind you are working in a very fragile piece of electronic equipment. The printed circuit board / the IPVR / the gas sending unit / and all the gauges in the panel have an ohm value, (can be tested for resistance using an ohm meter) to verify they are all good-or they have failed.
Am amazed I just found this as they were obsolete 10 years ago. I would question the country of origin, (and make sure you test yours first) before buying one though:
http://www.ebay.com/itm/1971-72-Ford-Tr ... Ht&vxp=mtr
Jeff
http://www.fordification.com/forum/view ... 22&t=46251
SOLD-71 F-350 dually flatbed, 302 / .030 over V-8 with a "baby"C-6, B & M truckshifter, Dana70/4.11 ratio, intermittent wipers, tilt steering, full LED lighting on the flat bed, and no stereo yet (this way I can hear the rattles to diagnose)! SOLD!
Many Ford bumps / one 76' EB / and several dents through the years.
A lot of "oddball" Ford parts collected from working on them for 34 years now!
2008 Ford Escape 4 x 4
jjdeal79
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Posts: 74
Joined: Fri Apr 12, 2013 5:14 pm
Location: Anchorage, AK

Re: Might have been answered elsewhere...guage questions

Post by jjdeal79 »

looks like i need some resistor wires too.... maybe the junkyard has an intact cluster harness. Got to love problem solving! I'll post progress...
-JJD-
1968 F100 4X4, 360, manual everything, project truck, 4th owner!
1972 F100, 360, C6 was “parts truck", heavily molested before I got it, but it runs great!
2004 Taurus wagon, original owner, 200,000+ and zero major repairs!
2020 F350 6.7 adventure machine
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