Case 580 Super L, won't start, 12V on ignition switch drops to 0V when switch is on.

Willie B said: My wife was not pleased. Click to expand... I get that a lot! She calls my 580 the 'Money Pit' every time I have to by a part!

@Willie B I did not mean to insult you with my post. My point being is your symptom is indicative of a poor connection. You need to measure voltage drop. This will help you find those added resistances(bad connections). You won’t find it measuring resistance or voltage when the circuit is not energized. I would check every connection between the battery and the ignition switch on the suspect wire.

edgephoto said: You are not losing voltage. You are measuring potential in an open circuit. Once the circuit is complete the voltage drops to zero volts because the circuit can’t supply the amount of current needed to make it work. Click to expand... Well said Edge! Edgephoto is 100% correct. I suggest following his advice. You definitely have high resistance somewhere in the wiring that feeds the key switch based on your voltage measurements.

If there is any swelling in either battery cable ? That is caused by some serious corrosion and will choke down current flow. Not long ago I had a cable that wasn't swollen, but I cut the insulation open at the battery connection and the copper strands were green. I then cut the full length of the insulation open and found that the strands were green from one end to the other. It was causing the symptoms you have. I had 12.45 volts with no load - 0.0 volts with a load on it. And it wasn't much of a load. It took a lot of time for me to figure that problem out. I thought I had a battery problem.

edgephoto said: @Willie B I did not mean to insult you with my post. My point being is your symptom is indicative of a poor connection. You need to measure voltage drop. This will help you find those added resistances(bad connections). You won’t find it measuring resistance or voltage when the circuit is not energized. I would check every connection between the battery and the ignition switch on the suspect wire. Click to expand... Gee, I took no insult. Another way to test for a bad connection is load the circuit. A big light works well. Then a voltmeter across a good connection will show no voltage, a bad connection shows voltage. In this case there must be good voltage throughout the high amperage starter circuit, and the relay circuit.

highwayghost said: I get that a lot! She calls my 580 the 'Money Pit' every time I have to by a part! Click to expand... My son hosts an antique tractor pull each fall. I haul my own tractors, and several for other people. Next day is clean up day. I spend the day moving tractors back where they belong. As the number of tractors declined, my wife looked at me: "how many of these are yours?" They aren't all mine, but six came to live in my sheds. Wives are an amazing thing! 8 tractors 300 feet from her back door, she doesn't know they are there.

Sorry for the silence, our internet service went out for two days and I hate typing things on a tiny phone screen. Anyway, I wanted to write to let everyone know that the problem is solved! I can't say if any one person or hint helped more than another, it was mostly just following multiple recommendations, looking at the schematics, and learning as I went. Never had a problem with this equipment yet, so as much as I hate problems, they allow me to learn so it wasn't all bad. Well on to the solution. I actually had two problems. One likely complicated finding the other. Inconsistencies in measurements led me to think grounding issue...so I eventually tracked one issue down to the ground strap that comes off the battery. The grounding strap was fine but would give variable readings when I was checking status of all the grounds on the machine. Obviously that shouldn't be. I went to remove the ground strap to check it and the bolt holding it into the chassis broke off as soon as I tried to remove it. It had corroded through and had enough metal for continuity, but the slightest movement would disturb it and I would lose ground momentarily. I extracted the remaining portion of the bolt and cleaned the threads, ground strap, etc and resumed troubleshooting. I eventually found the wire that sends signal to the starter had been worn through and was shorting to ground which is what was causing the voltage drop when I turned the key. Again, this was only sometimes and it depended on what I was doing and where I was doing it...same as with the grounding strap on the battery. So I was chasing two issues and I'm not sure which one was messing with me at which time. Once I got the ground issue cleared up, finding the short to ground was pretty easy. Well, that is my update! Thank you all for your suggestions and assistance! Hopefully this solution will help someone that reads this down the road with a similar problem.

DUH!!! NOT CLEAR IF ITS STARTING UP LOL

BlueDogDozing said: I can't say if any one person or hint helped more than another, it was mostly just following multiple recommendations, looking at the schematics, and learning as I went. Never had a problem with this equipment yet, so as much as I hate problems, they allow me to learn so it wasn't all bad. Click to expand... Thanks for the update! I'm always still learning too! Glad it's better now.

Thanks for the feedback. Was that 12 volt wire that was shorting to ground, unfused? I doubt that was your issue. You would have a blown fuse, arcing marks and/or melted insulation. The poor ground connection was more likely your issue. Glad you get things sorted out.

Remember that a series circuit divides voltage. Meaning each resistor gets some of the voltage. Each connection adds SOME resistance. In even the simple high amperage circuit from battery, to frame, through several bolted connections of mating castings, to starter frame, then through windings, to cable, through solenoid, and back to battery. There are dozens of likely points of resistance. Depending on its level of resistance, (ohms), each will rob you of some voltage. you don't have a lot of voltage to spare. If it is a starting issue the magnetic solenoid is another essential segment of the system. This is typically a little less sensitive to bad connections. I hear controversy about converting old machine voltage from 6 to 12. This does usually help overcome the hard starting, sluggish starter issues. A starter designed for six volts will be hard pressed to overcome loss of voltage in the circuit. Another approach is to fix the bad connections.

hello i'm new but I have a 1991 580k that was running great but the other day I started it and it died right away it will only run if you hold the key in the start position if you let it go it dies.....it is cutting power to the fuel solonid…...my ? is this a bad key switch or relay......thx dan

I can't remember, is that a 2-wire fuel solenoid, or 3? I actually own a 1991 580sk.

dano1963 said: hello i'm new but I have a 1991 580k that was running great but the other day I started it and it died right away it will only run if you hold the key in the start position if you let it go it dies.....it is cutting power to the fuel solonid…...my ? is this a bad key switch or relay......thx dan Click to expand... You probably have a bad fuel shut off solenoid. You should have one wire with constant voltage with key on, and another with voltage only key in start position. The hold coil in the solenoid usually goes bad. I don't remember if the solenoid is mounted on the inside of the injection pump on these models or not.

I have a 580K me & 2 adult sons use it. My younger son used it one day, he didn't have a key. I never knew. The process included unplugging a white wire from the back of the switch, attach it to a live terminal. Then another white wire touched to the live terminal for the starter. When it would start, but wouldn't run, we went through the system & discovered we were losing power to the valve ahead of the injector pump. Eventually tracked it to the key switch, found a wire on the wrong terminal. Quite a mystery! Eventually it came to light Zack had hotwired it, evidently replacing the wire on the wrong terminal.

All this talk about using test lights or meters and bad connections are rediculous. The key is just knowing ohms law. The voltage drop though a connection is proportional to the current. V=IxR. So for example if you have a 3 ohm resistance in a connection, but only micro or milliamps drawn by a meter, the voltage drop will be miniscule and you will read 12V. Make that 10Amps draw and your drop will be 10x3 or 30V in this example. So you'll read zero. Go ahead and use a multimeter, but know that you will get a different reading when you engage a heavy load.

Ooohhh boy!!!

jerbucc1 said: All this talk about using test lights or meters and bad connections are rediculous. The key is just knowing ohms law. The voltage drop though a connection is proportional to the current. V=IxR. So for example if you have a 3 ohm resistance in a connection, but only micro or milliamps drawn by a meter, the voltage drop will be miniscule and you will read 12V. Make that 10Amps draw and your drop will be 10x3 or 30V in this example. So you'll read zero. Go ahead and use a multimeter, but know that you will get a different reading when you engage a heavy load. Click to expand... Formulas are good, but most people don't remember them and are able to just remember to put one lead on this terminal, one on this one and do a test. And yes voltage drop will be zero if there is not sufficient flow of current. Of course the flow of current has to be proportional to the size of cable being tested. Big difference between 18 gauge and 2/0 cable. Most people can get a Digital Volt Meter but not many have DC clamp meters so we try to explain in terms they can understand. Your point is good but most will never remember unless they look it up. I remind myself that 40 years ago I just knew a few simple things and hoped to find something simple. Simon C

jerbucc1 said: All this talk about using test lights or meters and bad connections are rediculous. The key is just knowing ohms law. The voltage drop though a connection is proportional to the current. V=IxR. Make that 10Amps draw and your drop will be 10x3 or 30V in this example. So you'll read zero. Click to expand... Very interesting thread to bump into. I have been designing [and mostly repairing] electronics' for decades. Only yesterday I had a circuit showing a near short, this is a replacement module in a favourite trickle charger for our machines, which had faulted. The circuit on test failed when the supply voltage dropped causing a current spike which overloaded a microprocessor / display chipset to short circuit > parts bin. Solution is another board [I bought 5 at minimal cost] and supply better D.C. with a filter electrolytic capacitor added, now a constant current supply and voltage doesn't fall away as steeply with load. So the ohms, volts and amperes' are at play here and for the defect starter circuit I would use a test lamp, DMM [digital multimeter] or moving coil traditional analogue multimeter:

1. Put the meter / globe over the battery lead terminals
2. Watch the meter / globe and engage the switch
3. If, it doesn't alter, move to the next junction
4. Place the negative [black usually] meter lead on a clean chassis bolt and test again
5. If clear, next clip the + [usually red lead] on the switch / key terminal and black on a clean metal bolt / earth chassis terminal, if no or low voltage we are beyond the fault [resistive circuit] and have to trace back Its all basic logic to eliminate the weak point. What I can say is that miniatuarisation, since my initial Electronics and Communications' course, has reduced 'repairability' to module / assembly level [throw away] and a side effect is harmonic emission or broadband radio noise pollution from these technologies.