JSeery
Member Emeritus
Is it the "loop" type amp meter, or the "terminal" type Martin?
1940 ammeter wiring question.
- Thread starter FROG_PONDS
- Start date
mrfliboy
Senior Member
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
Attachments
![IMG_20160226_115726306[1].jpg](/data/attachments/228/228501-5fa85640b5641cdebe88418db8e98683.jpg?hash=6iLBogbMyv)
JSeery
Member Emeritus
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!
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.
Bruce Lancaster
Member Emeritus
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.
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.
FROG_PONDS
Member
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''
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)
FROG_PONDS
Member
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
bobwellsnoveltyshop
Well-known member
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
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
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.
Martin.
Flat Ernie
Senior Member
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)
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)