1940 ammeter wiring question.
 

I am restoring a 40 ford pickup that I got all apart. Let me start at the ''wiring'' beginning. Looking at the rear of the gauge cluster I see four gauges. The two on the left and the two gauges on the right have a brass bar between the two outside posts on both sets of gauges. I decided to install a''Rebel Wire''wiring harness with 8 circuits. The wiring diagram indicated a 10 gauge wire be run from the battery side of the solenoid thru a fuseable link to one post on the ammeter and from the other post on the ammeter to a junction box. Now it indicated to run a 10 gauge wire from the junction box over to the ''B'' post on the regulator. It also indicated to run a 10 gauge wire from the junction box to the fuse box. Before I ran the wires I removed the brass bar from the one post on the ammeter. Now my first startup I burnt up the fuseable link. After looking for a long time I found my dead short. I found out the ammeter was infact grounded at the post that had the brass bar. I then added a fiber washer to the post that was grounded, reconnected the wire and now I have no power to the fuse box. My questionis can I run both wires to one side of the ammeter and ground the other post? Rich

Re: 1940 ammeter wiring question.
 

Are you sure that is an ammeter and not a volt meter??

Bob

Re: 1940 ammeter wiring question.
 

Yes I am sure.

Re: 1940 ammeter wiring question.
 

40 pick up should have ammeter with a loop on the back side thru which a 10 gauge wire runs thru, this gauge only tells if it is charging (engine running) or not

Re: 1940 ammeter wiring question.
 

I do not understand at all what you mean. Rich

Re: 1940 ammeter wiring question.
 

Looking at the parts book 1940 used a battery charge indicator (volt meter) Part
01A-10844-B. That would be why there is the brass connector between the two gauges.

Bob

Re: 1940 ammeter wiring question.
 

The wiring diagrams show both the std and deluxe have a volt meter (call a battery indicator). Not sure on the pickup, but should be similar to the standard. An amp meter would not be connected using the brass strip, no way it would work that way.

Re: 1940 ammeter wiring question.
 

Most early Ford Amp Meters did not have connectors on them, just a metal loop that the wire from the battery passed through. There was no physical connection, the meter just senses the magnetic field around the wire.

Re: 1940 ammeter wiring question.
 

any way you can take pics of your gauges....front and back??....from looking at wiring schematics, there shouldn't be a bar between the oil pressure and voltmeter..there is a bar on the gas and temp gauges.....i think....looking at '40 truck wiring diagram, which i hope matches what you have....good luck....somebody will be able to help....Mike

http://www.vanpeltsales.com/FH_web/F...41-42truck.jpg

Re: 1940 ammeter wiring question.
 

OK --As I look at the gauge face I see the word ''BATT''. If it is a volt meter can I put a 6volt wire on one terminal and ground the other terminal? Rich

Re: 1940 ammeter wiring question.
 

whoops...looking at diagram for '40 car, i can see the two bars....sorry....Mike

http://www.vanpeltsales.com/FH_web/F...41-42truck.jpg

Re: 1940 ammeter wiring question.
 

Yes the bars were there as you discribed. I removed one because of the bad info given me from a very generic wiring diagram from ''REBEL WIRE''. and ended up with a short. I still think I can run a hot wire to one side and ground the other. Rich

Re: 1940 ammeter wiring question.
 

The Bar is the hot side, the other side is grounded. Have you looked at the wiring diagram for the 40 std? It shows it is grounded. You are going to have a hard time with the wiring without using the wiring diagram! Are you maintaining the Positive ground?

Re: 1940 ammeter wiring question.
 

Yes I am using several old ford wiring diagrams along with the REBEL diagram. So far I have everything working except for this gauge. My problem was not knowing that this was a voltmeter and the very vague information from BEBEL WIRE. Rich

Re: 1940 ammeter wiring question.
 

I'm surprised REBEL provided any information related to flatheads! The gauge may have been damaged with the previous wiring setup or may not have worked in the first place. try running some dedicated wires directly to it. In you earlier post you believed that the Bar was the ground side of the gauge, don't think that is correct. All of the gauges are connected together on the power side and then the grounds provided through the other terminal. The Temp, Fuel & Oil Press are grounded thought their sender units, the volt meter is grounded directly. So, based on your earlier post sounds like you have it connected backward.

Re: 1940 ammeter wiring question.
 

Thanks for all the help--Based on the information you ford lovers have given me I am going to connect it up as a voltmeter. The diagram given me from REBEL WIRE indicated an ammeter and I wired it up that way. They were very helpful when I called them but never said it could be a voltmeter. Thanks Rich

Re: 1940 ammeter wiring question.
 

Hi Rich, on the back of the ford battery voltmeter gauge there are two terminals, one of which has a piece of grey fibre insulating material under the inside terminal nut, so that is the terminal that is powered by the ignition switch via the brass strip. The other terminal has only one nut on it which screws down hard on the gauge casing which gives it a ground connection. Easy to tell an ammeter from a BAT or voltmeter gauge. The voltmeter needle is at rest at the bottom of the dial (with ign off) whereas an ammeter will have the needle at rest in the centre of the dial. Regards, Kevin.

Re: 1940 ammeter wiring question.
 

Kevin--That is exactly what I have. Thanks Rich

Re: 1940 ammeter wiring question.
 

The Ford voltmeter is 6V if you have changed to 12V you will have to put a voltage drop in the voltmeter circuit.

Re: 1940 ammeter wiring question.
 

40 pickup should be an ammeter, gauge cluster looks just like the "standard" car but has an ammeter instead of a battery volt indicator. Atleast that's what my 40 pickup cluster looks like.
Martin.

Re: 1940 ammeter wiring question.
 

Is it the "loop" type amp meter, or the "terminal" type Martin?

Re: 1940 ammeter wiring question.
 

My 41 truck is loop type/amp meter

Re: 1940 ammeter wiring question.
 

The wiring diagrams show the 41 Truck with a terminal style ammeter.

Re: 1940 ammeter wiring question.
 

On my wiring (Sacremento Vintage Ford) I used a combo of car truck commercial schematics/diagrams to finally get it all correct. None matched perfectly with original wiring. LOL

Bottom left is whats left, hard to see but loop style

Re: 1940 ammeter wiring question.
 

I have noticed that a lot on the wiring diagrams. Not sure if it is changes during a production year and the diagrams were not kept updated or if they were just sloppy with them in the first place!:rolleyes:

Re: 1940 ammeter wiring question.
 

Loop type, same as 41-47 pickup. Infact from what I've gleaned, the 1940 pickup cluster is identical to the 41-47, only the actual face paint is 1940 only. That looks like the 40 "standard" cluster but for the amp gauge (pickup) and battery gauge (car)
Martin.

Re: 1940 ammeter wiring question.
 

So...to get back to Frog...if it is a loop ammeter as noted above, there will be no actual terminals...the screws visible just secure the gauge. The loop looks like a little tin tunnel on back of gauge. The circuit that would connect there on a conventional 2 post ammeter (Ford did not use these at all between 1933--maybe 1950's) goes through the tunnel without interruption or metal contact but is the same circuit. In other words, where you have the 2 loop connectors meant to screw to ammeter you should connect the 2 ends and insulate the connection and send the uninterrupted wire through the tunnel. NO exposed metal or contact, just insulated wire through tunnel. If you go through tunnel in wrong direction for your polarity gauge will read backwards.
From memory, with negative ground I believe you want the wire as it comes from connection to battery/charging to pass through the tunnel from driver's side to exit toward passenger side, then to where it hooks up to fuses and lights and stuff.
If there are posts on the gauge it is not a Ford ammeter and would be a voltage gauge that does not carry the main current.

Re: 1940 ammeter wiring question.
 

It rained here all day today and the truck is now outside since it got too tall to work on in my gerage. I hope to get to the wiring tomorrow. I set the cab on and had to take the tires off to get it outside. Everything makes sence now that I found out I have a volt meter and not a ammeter. I picked up this truck in boxes over two years ago. It was taken apart in 1966 and stored. I discovered that the engine was overhalled in 1966 and I started it up after only three tries. The engine runs great. This is when I discovered that the generator was not charging the battery. I kept trying to wire it up as if I had an ammeter. After blowing two fuseable links I came to all of you ford lovers for advice. This is the best move I made because I learned a lot. I will let everone how it turns out when it stops raining. Thanks Rich "FROG''

Re: 1940 ammeter wiring question.
 

Frog ponds, If it helps at all? An ammeter is wired in series (part of the existing circuit) nearly all power goes through the ammeter wire)(fat wire) and a volt meter is wired in parallel (or if you like connects across an existing circuit.(thin wire and just measures the voltage across the circuit)

Re: 1940 ammeter wiring question.
 

Here is a photo (different year) of what the "loop" type look like.

Re: 1940 ammeter wiring question.
 

OK -- I went out and wired it up as a voltmeter and it srarted up and the battery is charging and the gauge indicates its charging. Thanks all Rich

Re: 1940 ammeter wiring question.
 

Can't beat that!!!!

Re: 1940 ammeter wiring question.
 

Negative 12 volt ground:

I'm in the same pickle..... so all i gottah do is power the gauges through the bars (with the voltage dropped), ground the voltmeter and run the other sender wires to the negative sides of the gauges?

Re: 1940 ammeter wiring question.
 

Not sure what happens with the voltmeter and a voltage drop! The other instruments should work fine, as should the voltmeter, I just haven't tried it.

Re: 1940 ammeter wiring question.
 

The 1940 ford standard, deluxe and the pickup truck and including the big 3/4 and up had a BATTERY gauge (volt meter, around 60 ohms in resistance, the face on the deluxe was different than the standard and truck. In 1941 ford pickups and big trucks started using the AMP gauge (measures amperage instead of volts. I have restored over 100 of these 1940 ford instrument clusters and still restore them.
I hope this helps on the battery gauge issue. And the brass jumper is suppose to be on both sides, (voltage side) and the other battery terminal goes to ground as the schematic (wiring diagram) shows.
BILL WELLS

Re: 1940 ammeter wiring question.
 

The 41 had a different gauge finish like the 42-47 didn't they? If that's so then what is my cluster out of? It's identical to the 40 "standard" except mine has a painted surround and an amp gauge. Color, finish, everything apart from those two things. Any idea what it's out of then?
Martin.

Re: 1940 ammeter wiring question.
 

The '40 BATT meter requires a precision 60 Ohm resistor wired in series with the gauge from 12V to get the correct reading.

A voltage drop will always read 6V or thereabouts. You want to read the relative voltage (12-14) and how it varies with the generator/alternator charging.

The absolute very best way to do this is to get a potentiometer (variable resistor) and wire it up with about 70 Ohms in series with the BATT meter and a 12V batter. Then adjust it down until the BATT meter reads roughly in the middle to lower end of the yellow band. Then just leave that in series with the gauge and 14V should read towards the very top of the green band and maybe slightly into the red band. 13.5V should be roughly the lower portion of the green band.

The value of 60 Ohms is derived from the Ford Service Bulletin outlining the overall resistance of the BATT circuit as stock. By doubling the resistance, you should keep the current through the BATT gauge equal with double the voltage resulting in equivalent readings (green = good charging)

Re: 1940 ammeter wiring question.
 

This is a very interesting thread for sure!!