Need help installing Factory ALT gauge in my 1966 F100
Hello all. I am new to this board and am in the need of some serious help. I did review a posting on the topic I have stated back in 06 on this board but I was hoping that I could get some clarification.
Basically how exactly does this ALT gauge connect? People are talking about an isulated block - what is that exactly and where can you get one? Others are talking about junction blocks with 1 or 2 posts. I know what these are but can these be bought? If so where? I do have a 30 AMP breaker with 2 posts so could this be used as the junction box/insulator block? I would then run a 10 gauge wire from the ALT BAT post to one side of this breaker. I would then use another 10 gauge wire and connect it to the other post of the breaker and run it to the gauge. I would then take a 3rd 10 gauge wire and run it from the gauge to the pos side of the starter relay. I have the original stock alternator on the truck and assume it is a 60 AMP so would the 30 AMP breaker be enought or will I have to switch it with a 60 or 70 AMP breaker OR do I just need a simple junction box or connect directly to the ALT BAT post and bypass the entire breaker/junction box? OR is this even needed if I used a 10 gauge fusable link wire??? I did have part of the original harness used to wire in the ALT and OIL gauge and the two wires coming off the ALT gauge were 8 gauge but were cut off and not sure where they were running to. Appeared to me that one was running directly to the alternator and the other to the start relay positive side. I would really appreciate if someone could very clearly state on the correct way to install the factory style ALT gauge into my 1966 Ford F100 3 spd column shift, 352 Custom Cab?? Thanks so much as I really do appreciate the help with this! Frank
You say you have a factory amp guage? If so, what do the terminals look like and where does it mount? I don't have a diagram for a 66, but in 67 the diagram shows a idiot light in the dash.
I did have a factory amp guage in my 53 f100, but it had no terminals. All it had was a loop that the wire ran through.
If your guage has two large terminals on the back, then it must be like an aftermarket guage. However it is, if we figure out what type of guage you have, we can get it working. The other type is the one that takes a shunt. It has very small wires and terminals on it. I am just not sure what you have there.
It is the factory gauge for Custom Cab F100s that has the two long studs on the back. Here is an old eBay link that shows a picture for your reference (hope you will be able to view it).
Tonight I tried the following while referencing the 1966 shop manual:
Used 14 gauge wire and spliced into the yellow wire going to the ignition switch and attached it to one post of the ALT gauge. Then I took another piece of 14 gauge wire and connected to the same post on the back of the gauge that ties into the ignition switch and connected it to the BAT terminal on the alternator. Lastly I took another piece of 14 gauge wire and connected to the other post of the ALT gauge and connected it to the positive side of the Starter relay. Exactly as described in the shop manual. I have two ALT gauges that I bought off eBay and both did not work in this system. Either this system is not correct for whatever reason OR both gauges are bad which would suck but good to know that is the damn issue. Whatever you can find to help me I would so greatly appreciate it! Thanks and looking forward to your response!
Opps forgot to mention that it mounts to the left of the fuel gauge on the instrument panel as this gauge and the oil gauge are extra as the stock instrument cluster for the Custom Cabs only had the Fuel and Temp gauges and idiot lights for Oil and ALT! I really think that the above system I tried should work as the idea here is to measure the AMP outage from the Alternator as it is recharging the battery. I tried this system with the truck running for a bit and even kicked on the headlights and not even a flicker from the needle in the gauge. Current is definitely moving through that ALT gauge as all wires were tested and have current! Should be simple but of course it is not so I am banking on the gauges being broken but that is not the feeling I have as they are in great condition as I tore them down when I restored the entire instrument cluster! Please help! Thanks again Frank
This is the way it should be wired. Be sure to use 10 guage wire, 14 is too small for this. Also be very careful with your wiring, since none of this is fused. It should be wired so it monitors the battery condition. If it's being drained it will show it. If it's being charged, it will show that.
I really do not understand the 2nd diagram? Instead of part of the alternator harness connecting directly to the solenoid it is going first through the gauge?
As it is now (on my truck) from the alternator part of the harness goes to ground on the block. The other part of the harness (from the alternator) then proceeds towards the pos side of the solenoid but splits and part goes to the voltage regulator on the radiator support and the other goes to the pos side of the solenoid. The + cable of the battery also attaches to the pos side of the solendoid and so does the warning harness that supplies the dash harness (instrument panel etc). The negative side of the solenoid supplies the starter. Can't imagine taking taking all those wires off the pos side of the solenoid (minus the pos battery lead wire) and making some sort of connection that goes directly to the ammeter.
Tonight I used 14 gauge wire and connected the BAT terminal of the alternator to the gauge and used another piece of 14 gauge wire to connect the other post of the gauge to the pos side of the solenoid. Needle did not move with the truck running. Problem is at that point the battery is fully charged so is the alternator charging at that point (test light indicated wire was hot)?? So instead of running the wire from the gauge to the pos side of the starter rely I just grounded it to get max current through the gauge (knowing that it could fry the gauge) low and behold the needle frantically flipped to the left (pos direction) but I quickly took it off ground as it sparked etc. So I am wondering if I have it connected correctly just need to wait until the alternator kicks in which may take some time - not sure?
Funny thing is the original stock harness for the ALT gauge that I found had an 8 gauge wire to each post and that was it as they were wrapped in the harness with the wires for the lights that supply that gauge and the oil gauge plus it had the oil sending unit wire wrapped in it for the same oil gauge. I am wondering if one ran directly to the alternator BAT terminal and the other to the rely or possible the negative terminal of the battery?? Basically the setup I tired with 14 gauge wire - if it worked - I was planning on fusing the wire to be safe but....
Where did you get that diagram from? Also a diagram in the shop manual has the post on the gauge that is connected to BAT terminal on the alternator also connected to the yellow wire on the ignition switch with the other post on the gauge connected to the pos side of the solenoid. I did this as well and the needle did not move with the truck running in the garage. I was thinking about putting the lights on and draining the battery a bit to ensure that the alternator is in charge mode and see if I get a reading?? One good thing about stupidly grounding the gauge (while connected to the alternator) is that the needle actually moved so maybe the gauge is good however I do not think I hurt it by grounding it. What do you think now??? Seems like it should be so straight forward???? Or is it?? Thanks for the help thus far and looking forward to your response! Frank
Yes, do not ground the gauge. The gauge is basically a short, so you shorted your hot wire to ground, and that's why the gauge pegged.
You keep saying the original harness had 8 gauge wire. This should be a big hint that the 14 you are using is too small.
You are not going to be able to see the charge of the alternator, if you do not run the alt through the gauge. That's why you have to take everything off the pos side of the solenoid, and run it through the guage. That is also why the wire has to be so large. Every electrical load on the truck, except the starter motor, is going to run through the gauge.
Do not worry about the other wires that go the regulator from the alternator. Just do what the second diagram shows above. Take all the small wires off the solenoid +, and wire them to the gauge. The hook the other side of the guage back to the solenoid. The gauge is a dead short, so the wires you took off the solenoid + will not know the difference, they will still think they are on that connection(if you use large enough wire like you are supposed to).
Thanks for this once again. However the wires from the alternator to the + side of the solenoid and the part of the harness that also connects to the + side of the solenoid that feeds the dash harness are not little wires. They gotta be 8 gauge + and have the ring terminal connection. I definitely do not want to cut the ring terminals of these original wires as I would have to to make them long enough to reach the gauge. I guess I would have to use a junction box on the fender apron to connect all those wires that were once on the + side of solenoid so that I could run one nice 10 gauge wire (with a fuse) from that junction box to the gauge and then use more 10 gauge wire from the other post on the gauge back to the + side of the solenoid.
Last question I have then is if I run a wire just from the BAT terminal of the alternator to the gauge and from the other post on the gauge back to the + side of the solenoid - why is that not going to work with the other wires still attached to the positive side of the solenoid?
You mentioned above that I would not see a charge if not run the alternator through the gauge but that is what I did and nothing happened - is that because all the wires must be removed from the positive side of the solenoid with the exception of the + battery lead?
Lastly were could I get a junction box that is insulated enough to connect all the wires from the positive side of the solenoid to and then run a 10 gauge wire from that junction box to the gauge? That is the only way I can see doing it but not sure were I could find something. Also the posts would have to be the same size as that found on the pos side of the solenoid??? Any ideas???
I don't mean to step on Franklin's toes, but the ammeter measures current flow(amps), not voltage. This being the case, all current used in the truck must flow thru the ammeter for it to work correctly.
If the truck previously had an ammeter, the wiring should already be there. One of the 8 gauge wires on the fender relay will go to one side of the ammeter. If the ammeter has been removed, or bypassed, the wires to/from the ammeter would have to be connected together someway, usually with a small machine screw behind the dash.
If the truck did not have an ammeter, and you are trying to add one, Franklin's second schematic is correct. How you get there would be up to you, but it would require some splicing of wires.
I see the gauge is out of a 65. If your truck was not equipped with the same gauge, and the wiring harness is the same from 65/66, then the large 8 gauge wire will be in the harness behind the inst panel. This would be the wire to tap into. Use a test light to check for continuity and tracing.
The large wire from the alternator supplies current to the battery. Tapping into this wire will not allow the ammeter to work properly.
A voltmeter is much simpler. It can be connected anywhere in the 12v switched circuit to measure charging voltage. jd
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In memory of my beloved Sandy, 9/28/53 - 1/24/03
I don't mean to step on Franklin's toes, but the ammeter measures current flow(amps), not voltage.
. That is correct, and I don't think I have messed up yet. We are on the same page.
Quote:
However the wires from the alternator to the + side of the solenoid and the part of the harness that also connects to the + side of the solenoid that feeds the dash harness are not little wires. They gotta be 8 gauge + and have the ring terminal connection. I definitely do not want to cut the ring terminals of these original wires as I would have to to make them long enough to reach the gauge.
If you look at the diagram, it describes these wires as bolted together and then insulated. So you would take all the ring terminals off, get another 8 or 10 guage wire and put a ring terminal on it, and then run a bolt through all these ring terminals and put a nut on the other side. Then insulated it with tape. This will not ruin any of your wires that you have now. If you do not like the bolt and tape idea, then you can put all the wires on a terminal or insulating block. This is what you were hinting at in your first post. If you had some thick plastic, you could make your own with a bolt sticking up through the middle to mount the ring terminals, and then smaller holes on either side to mount the plastic. Looking at your last sentence, I believe you are already thinking about doing this.
Exactly! What I will try, hopefully tonight, is do exactly what you described above:
Take the alternator harness and dash harness that are running to the positive side of the solenoid and add in a 10 gauge wire with the same size ring terminal end and put a bolt through it all with a nut and wrap in tape. Then connect to one gauge post. Then take another piece of 10 gauge and connect from the other gauge post back to the solenoid pos side! I may put in a fuse on the alternator wire side to be safe (would 30 AMP do it?). And hopefully this works. If it does than I will just need to find an insulator block to neatly mount all this stuff up as you mentioned above though taping it really nice and mounting that low on the fender my surfice for now. Let me know about what you think about putting in a 30 AMP fuse if that is a good thing or just go with the 10 gauge as is. Dave F - if it works I owe you big time! Thanks again for taking time to help me with this as I really do appreciate your assistance and guidance....Frank
You can try a 30 amp, but it may blow occasionally and be a nuisance. You probably do have at least a 60 amp alternator, and if you have or add any other loads, the 30 amp fuse is going to be borderline. If you would like to fuse it, I would get one of those maxi fuses that rated at about 60-80 amps. All you are doing is protecting the large wire running to the gauge. If it happened to short, it would definitely pull more than 80 amps and it would blow the fuse. Your original wiring did not protect this circuit, and many of the older autos were wired this way. Starting I think around the late 70's, they started using fusible links to protect some of these wires.
Before you tape the connection up, hook everything up, make sure the connection is not touching ground, and then go inside and turn on the headlights, or the blower motor, or both. You should see the guage go to negative. If it goes to the positive direction, then swap the wires on the solenoid and the bolted connection, or I guess you could swap the wires on the back of the gauge. Then when you turn on the load, with the engine off, it should go to the negative side.
OK. I hope to try this tonight and let you know something either later tonight or tomorrow! Sometimes hard to find the time with a 2 yr old on the loose. Thanks again for all of your time and advice and I hope this will put this issue to rest and then it is on to others. There are always issues.....Frank
YOU ARE THE MAN!!!! Thanks so very much. That was it exactly. I wired it all in with 1o gauge and no fuses and before I turned it on I hit the lights and the gauge immediately went to -30 AMPS which it should. Crank it up and it was + 15 - 30 AMPS. All that crap in the manuals and that is the DIAGRAM. Sweet. I owe you one! I will definitely be all over this if someone else gets into this mess. THANK YOU - THANK YOU! AWESOME! Thanks a whole bunch - made my weekend! Frank
Need help installing Factory ALT gauge in my 1966 F100
