Instrument Panel Wiring Help
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Instrument Panel Wiring Help
Okay--long time since last post. A quick recap: Bought a 76' F-100 last Nov with a faulty ignition wiring problem. Got an all-in-one dizzy because the wiring harness was butchered and spliced to hell. The day I put in the dizzy, I dropped a valve in the # 8 cylinder. So I took out the engine and rebuilt it. Well it's all back together and runs like a champ--I have to put in a tach to get the timing exactly right--did it once already.
My current problem is, now that the wiring harness is toast (I didn't keep it--dammit), I have no oil pressure gauge, no temp gauge, and no alt/charging gauge. I figure I just have to run wires to the dash harness plugs, but which ones?
I have all of the 76' Ford manuals, but the section on instrument panel wiring doesn't make much sense to me.
Can anyone help? Wiring tips? Pics(this goes to that, etc)? A link to a similar post?
Thanks.
My current problem is, now that the wiring harness is toast (I didn't keep it--dammit), I have no oil pressure gauge, no temp gauge, and no alt/charging gauge. I figure I just have to run wires to the dash harness plugs, but which ones?
I have all of the 76' Ford manuals, but the section on instrument panel wiring doesn't make much sense to me.
Can anyone help? Wiring tips? Pics(this goes to that, etc)? A link to a similar post?
Thanks.
Senior User
Joined: Apr 2012
Posts: 324
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From: Spencer Mountain, NC
This link should take you to wiring diagrams that will help.
1973-1979 Ford Truck Wiring Diagrams & Schematics - FORDification.net
Have fun!!!
1973-1979 Ford Truck Wiring Diagrams & Schematics - FORDification.net
Have fun!!!
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
Does your fuel gauge work? Or is the problem isolated to the oil and temperature gauges?
The ammeter (charge gauge) is independent of the other three gauges, and never actually worked in the first place. If it stays pegged in the middle, it's doing all it really ever did in the first place. So you may be able to take that out as a variable.
The ammeter (charge gauge) is independent of the other three gauges, and never actually worked in the first place. If it stays pegged in the middle, it's doing all it really ever did in the first place. So you may be able to take that out as a variable.
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Canus--thanks. I found those a while back--a little out of my element. I have a buddy who's pretty good with electric, so I'll print those for him.
FMC--Fuel gauge works.
I'm gonna fiddle around today to see what I can figure out.
FMC--Fuel gauge works.
I'm gonna fiddle around today to see what I can figure out.
Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
The wiring for the oil and temp gauge is actually fairly simple.
Originally there was a white w/ red trace wire that went from the oil pressure sender to the plug on the instrument panel. For the coolant temp it was a red w/ white trace wire. It too went to the plug on the instrument panel.
Originally there was a white w/ red trace wire that went from the oil pressure sender to the plug on the instrument panel. For the coolant temp it was a red w/ white trace wire. It too went to the plug on the instrument panel.
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Thanks, Mike. That sounds easy enough. I'll try to get it done tomorrow. Should the wire go straight through the firewall to the inst panel, or is there a plug in the eng comp? I'll try to get a pic of what I mean tomorrow.
Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
Towards the center of the firewall, behind the engine, there should be a flat plug that looks like one of those flat trailer wiring plugs, only this one will have three wires going to it, a white w/ red trace, a red w/ white trace and a red w/ green trace. That's the plug you're looking for. The White w/ red trace is the oil pressure, red w/ white trace is coolant temp and the red w/ green trace is for the ignition coil.
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Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
First, unplug the sender. If the gauge stays "C" then go ahead and replace the sender.
Postmaster
Joined: Sep 2013
Posts: 2,595
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From: Pasadena, Ca
Is there a schematic for the harness for the gauge cluster? Im going to make an overlay for aftermarket gauges and would rather not have to trace the wires if i dont have to. Im hoping to make an interconnect harness so im not butchering the existing one
Hotshot
Joined: Apr 2009
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From: Stanley, VA
1973-1979 Ford Truck Wiring Diagrams & Schematics - FORDification.net
Don't know how the interconnect would work. The harness plugs into the back of the instrument cluster. You'd need to fabricate some kind of female plug for the harness connector to plug into. Plus the factory ammeter uses a shunt type of feed rather than a direct wiring to the alternator. That would need to be addressed too.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Check the resistance of your sending unit. That almost sounds like what happens when you install an oil pressure sending unit that's meant for an oil pressure warning light instead of a gauge (even though you're working with the temperature gauge). This is a simple measurement; you can measure between the sending unit stud and a good, solid and clean ground.