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tongy66086 
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Joined: 07 Jul 2012
Location: Tonganoxie, KS.
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 Topic: AC 175 starting issue
Posted: 28 Jan 2025 at 2:51pm |
I have an Allis Chalmers 175 diesel, that has developed a problem. I went out to start it, and got nothing when I pushed the start button. I assumed the button was my issue, but it's not. New button, same issue. I can turn the key on, and short across the solenoid, and get the tractor to start. Does that tell me that I have a wiring problem? If so, is the attached schematic correct on how the wiring would be? Thank you so much for your help.
Edited by tongy66086 - 28 Jan 2025 at 2:54pm
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DrAllis
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Posted: 28 Jan 2025 at 3:01pm |
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Foot clutch pedal has to be all the way down. Could be a bad switch there on the clutch pedal rod.
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tongy66086
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Posted: 28 Jan 2025 at 3:03pm |
The clutch switch has been wired around years ago. Thank you.
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DrAllis
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Posted: 28 Jan 2025 at 3:15pm |
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A bad connection at that location, depending on how it was done. The push-on female/male spade connections at the key switch get rusty and are troublesome as they get on.
Edited by DrAllis - 28 Jan 2025 at 3:36pm
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Les Kerf
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Posted: 28 Jan 2025 at 3:34pm |
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Ummm... the way you have it drawn in your schematic you are sending Positive (+) voltage to both sides of the solenoid; no current will flow because both sides are at the same potential.
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8070nc
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Posted: 28 Jan 2025 at 3:56pm |
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The the negative is supplied through the frame of the solenoid and starter
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1984 80780
1957 D14
DES 300 with 25000 engine
616 tractor
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ekjdm14
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Posted: 28 Jan 2025 at 4:04pm |
 Les Kerf wrote:
Ummm... the way you have it drawn in your schematic you are sending Positive (+) voltage to both sides of the solenoid; no current will flow because both sides are at the same potential.
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More than that, the starter is missing from the drawing. Best way would be get a cheap multimeter & find out where you're losing power.
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Model 70
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Posted: 28 Jan 2025 at 7:05pm |
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Put a test light on the small terminal on the solenoid,when you push the button if you have power going to it and it doesn’t turn over you probably need a new solenoid if jumping across both big terminals actually starts it. Hit the old solenoid with something,lot of times they stick
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sparky
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Posted: 28 Jan 2025 at 8:32pm |
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Clean all the terminals and use a good tester.
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It's the color tractor my grandpa had!
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DanielW
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Posted: 29 Jan 2025 at 12:35pm |
Which way did you 'short across' the solenoid? If you went across the two main terminals ('A' in picture below) and it started, that would have bypassed the solenoid and jumped the starter. Which tells you your solenoid is bad/sticky (very common). Or that the solenoid is energizing a field and sucking in, but not making full contact across the two terminals inside. In either case, that would imply a bad solenoid. If you went from the solenoid terminal connected to the battery to the small solenoid excitation wire ('B' in picture below), that would imply the solenoid's working and you're losing power to the solenoid. In which case, verify with a multimeter and start tracing wires and checking switches.
Edited by DanielW - 29 Jan 2025 at 1:50pm
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tongy66086
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Posted: 29 Jan 2025 at 1:50pm |
Thank you so much.
I jumped it like B, in your picture. I was suspecting a wiring issue, but at the moment, I don't feel like standing in 6" of snow and a windy 20 degrees.
DanielW wrote:
Which way did you 'short across' the solenoid? If you went across the two main terminals ('A' in picture below) and it started, that would have bypassed the solenoid and jumped the starter. Which tells you your solenoid is bad/sticky (very common). Or that the solenoid is energizing a field and sucking in, but not making full contact across the two terminals inside. In either case, that would imply a bad solenoid.If you went from the solenoid terminal connected to the battery to the small solenoid excitation wire ('B' in picture below), that would imply the solenoid's working and you're losing power to the solenoid. IN which case, verify with a multimeter and start tracing wires and checking switches.
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Les Kerf
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Posted: 29 Jan 2025 at 3:59pm |
8070nc wrote:
The the negative is supplied through the frame of the solenoid and starter |
Well, you know that, and I know that, but we don't know if the original poster knows that. We are dealing with an unknown person on the internet and we don't know much about his level of expertise other than the obvious fact that he asked for assistance in troubleshooting a basic DC circuit. There is no shame in that, as we all had to start somewhere, but when I see an incomplete schematic I immediately presume that we need to address the fundamentals first.
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Les Kerf
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Posted: 29 Jan 2025 at 4:02pm |
tongy66086 wrote:
Thank you so much.
I jumped it like B, in your picture. I was suspecting a wiring issue, but at the moment, I don't feel like standing in 6" of snow and a windy 20 degrees. |
Yup, when the weather warms up a bit just start checking for voltage drops in the control circuit through the key switch and push button.
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