Farmall M ammeter randomly spiking

[Janicholson]

I separated those two connectors touching. Nothing different happening. But can you tell me if all the wires on the light switch are right? The lights are live. They turn off with the light switch but I don't have to tun on the pull switch to turn the lights on. So I have to have the lights wired wrong somewhere. And the amp gauge still maxed out.

The lights should have a bright and dim switch positions. They are not connected to the ignition, so they can be off and on anytime. Jim

 

[Jim Becker]

Unhooked the wire that runs to fuse/then headlight component. Started tractor and ammeter gauge was then "pegged full time". Left the black wire on ammeter that runs to back of pull switch.

When I suggested disconnecting the headlight switch, the idea was to take the headlight circuit out of the picture until the problem was resolved. I expected disconnecting it to either eliminate the problem (problem in the light switch/circuit), or there would be no change (problem somewhere other than the lights). You reported a third outcome with the problem still there but changing. That doesn't make a lot of sense to me. What else could have changed when/while you disconnecting the light switch? By the way, with the lights disconnected, that oversize loop at the switch can't be the cause of the problem either.

Your small panel that holds the ammeter, light switch, etc. is just resting on the tractor. Try picking it up so it doesn't touch anything. Then deliberately ground it against something. Does that make the problem come and go?

 

[caterpillar guy]

Our H will peg the amp meter when first started then it will drop back as it charges up. IT does not wiggle when in use unless you change the load like turn on the lights and it will go to a slightly higher level and stay thertill they are turned off. SO i would say you have a problem in the light5 switch casu\gn most of your porblems like that eye on that lapping wire and having to wiggle the switch for them to work. I would think you want the load on the oppsite side from the supply or Alternator in this case so the laod would read through the amp meter. With the lights on the same side as supply/alternator it would not read the difference when the lights are on or off. Might try putting the wire to foot switch to the battery direct just to see if that switch is shorting to grd. Might no be shorting but just leaking through a cracked insulation or os especially if wet or damp like a wet day.

 

[used red MN]

They turn off with the light switch but I don't have to tun on the pull switch to turn the lights on.

That is correct and the way it was from the factory. You must have not been around many vehicles made from the 1930s or earlier through vehicles built in the 80’s and probably the 90’s as well. They for the most part all had lights that turn on regardless if the ignition is on or off. In many cases the headlights are the heaviest electrical load. The ignition circuit is the most important circuit on a vehicle and the one that needs to be the most reliable. The factory knew running the headlights through the ignition switch contacts was asking for a higher failure rate so that was avoided. Now days with relays and body control modules the path of the lighting circuits are anybody’s guess.

 

[BarnyardEngineering]

If the ammeter needle pegs at full charge and does not come down after a few minutes, the regulator on your alternator has failed and it needs to be replaced. The quality of inexpensive big-box parts store rebuilt Delco 10SI alternators is hit and miss.

The electical system on a Farmall M is dead simple. Either you have it wired right, or there's smoke. There's no in between. Nothing you can do to the wiring can hurt the alternator, except hooking up the battery backwards.

 

[560Dennis]

Go over your wiring with vom. Corrosion on contact s , frayed connections , light resistor ohm is very important , Good ground on the light switch are all critical to the safety , electrical system , all these issues need to be corrected , hope this helps, you got checking to do

 

[706man]

Ordered a new light switch and 60 amp ammeter. Gonna replace or clean any bad wiring. Someone asked about insulating washers. There aren't any on the ammeter poles. Gonna pick up some of those too. Thinking that might be causing issues.
I saw that "squatch" on youtube had a better sure fire way to ground headlights, etc so I am going to take a look at his video again.

I appreciate all the help on this! I'm 57 by the way to whoever said I probably haven't been around many vehicles made in the 30's thru the 90's. I am way better at house electrical the vehicle electrical that's for sure.

 

[Jim Becker]

. . . Someone asked about insulating washers. There aren't any on the ammeter poles. Gonna pick up some of those too. Thinking that might be causing issues.

It looks like your ammeter is held in place by a plastic clip. If so, insulating washers are not needed. The washers are used to insulate the ammeter lugs from a metal clip.

 

[706man]

Thanks Jim!. Thought maybe I lost them when I put the ammeter in last year.

 

[560Dennis]

Check and make sure the elec control box is ground also.

 

[used red MN]

Check and make sure the elec control box is ground also.

Although it’s a good thing to check if it is grounded properly to avoid wild test meter readings if an electrical circuit seeks a ground from it. However, on an 3 wire alternator install whether the box is grounded or not has no affect on how the alternator charges or what the ammeter reads. It is important on a generator set up, particularly those that are set up using the high and lo charge on the light switch.

 

[BarnyardEngineering]

Thanks Jim!. Thought maybe I lost them when I put the ammeter in last year.

Nope, that's one of those "It's either wired right, or there would be a fire," things. The ammeter is connected directly to the battery with no fuse, so if you short it to ground, you get heat, smoke, and fire in very short order. If you're lucky the wire burns off before things get out of hand.

 

[706man]

I am revisiting this topic cuz I never finished the project. Here is a diagram of how I believe it should be wired. Either it's right or wrong. Hopefully I am told it's correct. Thanks for all your help. I am also eliminating the ballast resistor with this work.

 

[Jim Becker]

Well, it is close to right. I don't know what B and L are on an ammeter (guessing Battery and Load), but the green wire belongs on the same lug as the red wire.

 

[used red MN]

Well, it is close to right. I don't know what B and L are on an ammeter (guessing Battery and Load), but the green wire belongs on the same lug as the red wire.

I agree with Jim, also if you reconnect the light the power to them would go to that same terminal you marked as L. On an ammeter installation the battery power goes on one terminal by itself all others go on the opposite terminal. This way it shows system charge or discharge in relationship to the battery.

 

[Jim.ME]

If it is a Delco 3 wire type alternator it is missing the excitation wire and the system sensing wire. The drawing is for a one wire alternator. I agree the green wire going to the ignition switch should be on the L terminal of the ammeter (and any other loads, like lights, that might be added later).

 

[706man]

Sorry guys. The picture of the wiring layout I made was how Dan and Rachel Gingell wired their H in a video. But my alt has the white clip on the edge of alt with red and white wire. The red wire on the white clip ties to the main lug on the alt and the white wire on the alt clip ties to the near side of the ballast resistor labeled red in the picture. Right now, my tractor starts(but pretty sure alt is not charging), lights work and no fire. But as I said, the mechanic that wired this 30 years ago tied different color wires together at times so I confused everyone in my original post when showing that. So I want to start from scratch. So here is a new picture with pretty much no connections showing. But everything is labeled. I just really don't want to ruin the new amp gauge or have a fire. Now there is a possibility that maybe my alt is not charging. I believe it is at least 30 years old. And it looks like Steiner has a 63 amp one wire alternator. So as I said earlier I am taking out the ballast resistor and guessing you guys can tell me what to do with the red(Q) and white(gray/R) wires from alt.
If you can tell me all the connections that would be great! Then I won't have to bother you anymore.

P.S. Just attaching extra pics for any kind of reference. Like I said. I want to start from scratch with all new correct gauge wires.
Mike

 

[Jim.ME]

As far as parts, this site is supported by the parts YT and PartsASAP sell, no need to advertise for Steiner when YT has the parts. JMHO

Below are the basic wiring diagrams done by Bob M for one-wire and three wire Delco 10SI alternators which should give you the info you need to wire your tractor correctly for which alternator you choose to use.

 

[706man]

So if I have a 12v internally resistant coil, then I can omit the ballast resistor out of either wire runs in both pictures?

 

[used red MN]

So if I have a 12v internally resistant coil, then I can omit the ballast resistor out of either wire runs in both pictures?

If you are referring to the “diagrams” Jim has posted the answer is yes. That essentially means that the terminal circled in red on the attached photo will go to the plus side of your coil. That wire branching off of it to the #1 terminal of your alternator can remain and take the place of what is shown on his diagram with the 5 circled in the upper left corner. There is either a resistor or diode in it that needs to remain in place. When done I would test for power at terminal 1 on the alternator with the key on to make sure everything is right with the world there. All said, there is nothing saying that your alternator is working properly. Also another I’ll ask is how tight is the belt for the fan off of the crankshaft pulley?