Alternator gauge
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Senior User
Joined: Jun 2007
Posts: 218
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From: Colorado
Alternator gauge
I am on a roll with the factory instrument panel .Speedometer rebuilt , new cable housing , new cable (took a couple times to get the length right ) . Oil pressure sender failed ( slow leak ). New sender all is good .New coolant temperature sender ( seems like it reads low ) . Fuel gauge started working after I jiggled some wires on the tank switch below the light /wiper switches . Shouldn't be too hard to find that issue .
I tried google for FTE 75 ford alternator gauge with no luck . Gauge seems to be on the positive side of middle all the time . Where does it draw it's current from ? Also wondering about the temperature gauge ? It stays low ?
I tried google for FTE 75 ford alternator gauge with no luck . Gauge seems to be on the positive side of middle all the time . Where does it draw it's current from ? Also wondering about the temperature gauge ? It stays low ?
Post Fiend
Joined: Jan 2006
Posts: 5,037
Likes: 9
From: Kasson, Minnesota
Factory gauges always seem to be inaccurate and untrustworthy. I have hardly ever seen my ammeter gauge move. It's nice to have a set of mechanical gauges oil, temp and volt. Than you can really know how things are working.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
The factory ammeter is a "shunt" style ammeter. There is a relatively heavy-gauge wire between the alternator output and the battery. A lighter-gauge loom of wire is electrically in parallel with this main feed; this parallel "shunt" runs to the ammeter and back. Needle deflection is a function of current through the shunt, which in turn is a function of current to or from the battery.
Normally the gauge stays centered; it's very coarse and essentially useless. If it steadily reads toward C or D, it could be a real indication, or the gauge itself could be damaged. Moving the needle by hand can actually permanently bias it toward one direction.
You're going to have to give more information here. What does "low" mean? Low relative to what? The gauge is useless for anything beyond a general go/no-go indication, because it's entirely subjective. There are electrical measurements one can do to qualify its behavior, but translating this to actual engine temperature is futile. As said above, pick up a set of aftermarket mechanical gauges if you really want to know what's going on.
Normally the gauge stays centered; it's very coarse and essentially useless. If it steadily reads toward C or D, it could be a real indication, or the gauge itself could be damaged. Moving the needle by hand can actually permanently bias it toward one direction.
You're going to have to give more information here. What does "low" mean? Low relative to what? The gauge is useless for anything beyond a general go/no-go indication, because it's entirely subjective. There are electrical measurements one can do to qualify its behavior, but translating this to actual engine temperature is futile. As said above, pick up a set of aftermarket mechanical gauges if you really want to know what's going on.
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Senior User
Joined: Jun 2007
Posts: 218
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From: Colorado
I have several Autometer , (not Autogauge )gauges of both mechanical and electrical style (oil pressure , amp , trans temp , fuel ratio , etc.)And they have been hooked up and used.
What I am looking to do is refine my use of the factory gauges .
The coolant gauge always reads on the low side .
What I am looking to do is refine my use of the factory gauges .
The coolant gauge always reads on the low side .
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Again, I think I'm missing some information here. Are you saying you used an aftermarket gauge to determine that the engine operates at a nominal temperature, therefore you expect the factory gauge to be centered? If so, what do you consider nominal? If not, how do you know the engine isn't running cool to begin with (stuck open thermostat, etc)?
Laughing Gas
Joined: May 2006
Posts: 1,140
Likes: 13
From: Port Orchard Wa
The factory ammeter is a "shunt" style ammeter. There is a relatively heavy-gauge wire between the alternator output and the battery. A lighter-gauge loom of wire is electrically in parallel with this main feed; this parallel "shunt" runs to the ammeter and back. Needle deflection is a function of current through the shunt, which in turn is a function of current to or from the battery.
Normally the gauge stays centered; it's very coarse and essentially useless. If it steadily reads toward C or D, it could be a real indication, or the gauge itself could be damaged. Moving the needle by hand can actually permanently bias it toward one direction..
Normally the gauge stays centered; it's very coarse and essentially useless. If it steadily reads toward C or D, it could be a real indication, or the gauge itself could be damaged. Moving the needle by hand can actually permanently bias it toward one direction..
So. While you're in there get one of these; Rocketman's Classic Cougar Innovations
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Senior User
Joined: Jun 2007
Posts: 218
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From: Colorado
Been through the thermostat thing . Started with a 180 high flow when the engine was first built . Running a 190 now . I am trying to figure out how to calibrate the gauge .
Thinking about building a housing to hold the gauges that would sit about where the radio speaker is , if it comes to that .
Thinking about building a housing to hold the gauges that would sit about where the radio speaker is , if it comes to that .
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Senior User
Joined: Jun 2007
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From: Colorado
I just looked at the voltmeter from Rocketman . That is the direction I would like to go .
Cool . Thanks
Cool . Thanks
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MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
You're still not answering my question.
To answer your question, the gauge itself cannot be calibrated. Needle deflection is purely a function of current through it. The gauge itself rarely is a problem unless it has physically been manipulated. You have not proven to me that your gauge is not reading the way it is because that's really what it's supposed to be reading. And, nonetheless, it's a moot point anyway. Whether the gauge points straight up, halfway between the "N" and the "O", etc is all meaningless because it doesn't correlate engine temperature to any discrete scale.
To answer your question, the gauge itself cannot be calibrated. Needle deflection is purely a function of current through it. The gauge itself rarely is a problem unless it has physically been manipulated. You have not proven to me that your gauge is not reading the way it is because that's really what it's supposed to be reading. And, nonetheless, it's a moot point anyway. Whether the gauge points straight up, halfway between the "N" and the "O", etc is all meaningless because it doesn't correlate engine temperature to any discrete scale.
Postmaster
Joined: Oct 2010
Posts: 4,656
Likes: 4
From: Northern and Southern Cal
No he doesn't.
But he is very direct.
Trust me, he knows the electrics on these trucks like no one else.
His mind operates like a computer. I know a lot but I can't do what he can.
Please do yourself a favor and just answer the questions, it will only help you.
I have nothing but respect for fmc.
But he is very direct.
Trust me, he knows the electrics on these trucks like no one else.
His mind operates like a computer. I know a lot but I can't do what he can.
Please do yourself a favor and just answer the questions, it will only help you.
I have nothing but respect for fmc.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Do you care to explain why? You came here for help, and I asked you a question to help me help you. After two or three tries, you still won't play ball. If you're not interested in giving folks the information they need to help you, then why come here at all? We don't get paid to do this, you know. My responses to this thread have been nothing but purely technical explanations with a handful of requests for you to clarify what you're trying to say.
Thanks for the kind words TH.
Thanks for the kind words TH.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 785
From: Simi Valley, CA
E8UZ-10883-A (replaced D3TZ-10883-A) .. Temperature Gauge / Obsolete ~ Dozens available NOS
Applications: 1973/79 F100/350 - 1975/91 Econoline - 1978/79 Bronco.
The temp gauges on these trucks tend to read on the cool side and if the optional Super Cooling radiator is present, it only makes the situation worse.
Standard/Xtra Cooling/A/C radiators: 26 1/4" wide x 19 3/4" high. The thickness of the core varies depending on which radiator is present.
Super Cooling radiator: 26 1/4" wide x 24 3/16" high. Has a HUGE top tank that is wider and deeper than the other radiators top tanks.
1973/79 F100/350 all I-6's and V8's: The factory installed thermostat was 190 degrees.
But some people complained when these trucks were new, that the temp gauge needle barely climbed above the C mark, but there was nothing the dealers could do about it.
Applications: 1973/79 F100/350 - 1975/91 Econoline - 1978/79 Bronco.
The temp gauges on these trucks tend to read on the cool side and if the optional Super Cooling radiator is present, it only makes the situation worse.
Standard/Xtra Cooling/A/C radiators: 26 1/4" wide x 19 3/4" high. The thickness of the core varies depending on which radiator is present.
Super Cooling radiator: 26 1/4" wide x 24 3/16" high. Has a HUGE top tank that is wider and deeper than the other radiators top tanks.
1973/79 F100/350 all I-6's and V8's: The factory installed thermostat was 190 degrees.
But some people complained when these trucks were new, that the temp gauge needle barely climbed above the C mark, but there was nothing the dealers could do about it.
Thread Starter
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Senior User
Joined: Jun 2007
Posts: 218
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From: Colorado
Sorry for speaking out fmc 400 . I do appreciate your help .
The temp gauge has been higher .
Looks like my best alternative is to hook up the mechanical set that I have on the shelf.
The temp gauge has been higher .
Looks like my best alternative is to hook up the mechanical set that I have on the shelf.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
No worries. In reality, however, it's not really appropriate to make an apples-to-apples comparison between actual temperature as measured on an aftermarket gauge, and relative needle position on the factory gauge. To my knowledge there are no published specifications that correlate position along the "NORMAL" range and actual temperature. And there's nothing that says what many consider to be nominal (190-195 deg. F) actually represents the center of the gauge.
There are electrical measurements you can do to make sure the gauge operates as best it can, but that still doesn't really tell you anything about actual engine temperature. If that's a number you're truly interested in, an aftermarket mechanical set is the way to go. The factory gauge is inaccurate and ambiguous.
There are electrical measurements you can do to make sure the gauge operates as best it can, but that still doesn't really tell you anything about actual engine temperature. If that's a number you're truly interested in, an aftermarket mechanical set is the way to go. The factory gauge is inaccurate and ambiguous.