Craftsman Tractor - No Start with Key

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  #1  
Old 01-13-04, 05:21 PM
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Craftsman Tractor - No Start with Key

Got another question here ... I became the lucky owner of a Craftsman lawn tractor (couldn't pass up the price - FREE!!). It had some things needed fixing, and I've got them all done except one. You cannot start it with the key, you need to jump it (which I do NOT like doing) and then choke it to kill it. Other than that, it runs beautiful.

I'm trying to trace down the starting now. Does anyone know where I can get a schematic? I don't know which engine it is (Briggs, Tecumseh, etc), but it's a 12.5 hp OHV Gold, model number 143-426122, Ser 2090D. I can find it on the Sears website, but no schematic. I may have found one thing so far ...

The cable from the battery positive attaches to some type of switch or solenoid(?). From here, one cable goes to the starter, one lead to ground, and one lead goes to the switch underneath the seat. On this last lead, should it show 12V with a meter coming from the switch? It seems to me like it should, then once you sit down and connection is made, it allows voltage to pass.

Thanks for any and all help!
Jeff
 
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  #2  
Old 01-13-04, 06:31 PM
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Yea, NotMrWizard, the model number you gave was for the engine. Look for the model number plate mounted on the tractor just in front of the seat by the shift lever. There should be another Sears model number for the tractor itself. Then if you go back to the Sears parts site you will probably find an electrical diagram. I've been working on a Sears lawn tractor myself and I found one there but I had to use the TRACTOR model number. I wouldn't be suprised to see some safety switches installed. A seat switch and a neutral safety switch are two that come to mind that I have on a 1974 model. It's funny that you can't KILL the engine with the key switch. Sounds like the key switch itself may be defective along with a few other things.
 
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Old 01-13-04, 07:11 PM
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Your keyswitch probably defective if you can't kill the engine with the keyswitch. In order for the keyswitch to kill the engine it must ground the kill wire. When you turn your key to the left position it makes two pieces of metal touch each other inside it. That kills the engine. That is the same thing as taking the kill wire yourself and touching it to a screw or the frame. That will also produce the same effect. As far as jumping it is concerned. My guess is that you need to charge your battery really well. I am thinking at least 72 hours. If you still have to jump your tractor, than that means your battery is bad and needs a new battery. If you take care of a battery really well, it can usually last way past a year. I am talking about at least 2 years of battery life. If this is the case. You can buy a lawn and garden battery for 30 bucks MIN. To me, that is cheap. Another thing I would make sure you do is make sure the pto is not engaged when you start the engine. If it is that will put a large strain on the startor. Most tractors now days will not let the engine start with the pto engaged. If this is a old tractor, I would inspect it thourghly. I have given you plenty info for now, do these things and let us know how it goes...
 
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Old 01-14-04, 12:32 AM
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Hello Jeff!

By jumping it, I assume you mean across the solenoid? Or from the battery straight to the starter? Is the battery good? You can try charging it, but not for days...that can warp the plates and internally short the battery. Look for a black wire coming from the engine. Make sure it is connected to the leg on the switch with a "M" marked on it. This is the wire that kills the engine. The sears site should show you a diagram of the mower.

You can get a replacement battery for $19.99 at advance auto parts, or other auto parts stores.
 
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Old 01-14-04, 06:14 AM
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Thanks for the help. I got the tractor model number, and found the wiring diagram. That will be a big help.

I guess that "jump" wasn't the right word for how to start it, and I meant by what Cheese said, going straight from the battery to the starter. The battery is good, holds a good charge and all, the power is just not getting through. I'm thinking that maybe there is a disconnect somewhere going to the ignition switch, as none of the terminals show any power on them.

Thanks for the help!

Jeff
 
  #6  
Old 01-14-04, 06:19 PM
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Well, still no luck. There were some wires disconnected that I was able to figure out where they go. I got the wiring diagram from the Sears website, which was helpful though hard to read in a couple areas. I do have two white wires coming off the solenoid that don't show on the diagram, but they go to the interlocks, and look like they are meant to be there. It looked like the previous owner was doing some cutting/unhooking stuff to bypass the safeties.

I've got power going to the switch now, but not really sure what else to look for. The fuse is good, PTO not engaged. I've not tried starting it off the battery to see if the ignition switch kills it yet. Is there a way to test the different switches? I just don't want to blindly start replacing them to try to fix it. One thing I thought was interesting, is that I at least thought the light switch would show power to it with the ignition off, but there's nothing on either contact (even with the key in the "on" position). It's not too old, I'd guess mid-80's. Has 2 interlock switches, a plunger switch under the seat, and the solenoid. Model number in case anyone has any info is 917.254750.

Thanks for all the help (and sorry so long)!

Jeff
 
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Old 01-14-04, 08:29 PM
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I looked at the circuit provided by Sears. Boy, they don't really provide a schematic. It looks like they have 3 different interlock switches. In any event, what you will have to see to get this thing to start will be the following:

1) You will have to see a constant +12 volts on at least one of the terminals on the starter switch.

2) You will have to see +12 volts on another terminal only when you turn the key to the start position. This voltage should then go away when you release the key.

3) The +12 volts you have only when the you put the key in the start position will have to be delivered to one of the small terminals on the starter solenoid via the interlock switches.

4) The start solenoid probably has to be grounded. I've seen this cause a no start condition before on starting solenoids with only three terminals.

5) All three of the interlock switches will have to be closed for the voltage to be delivered to the starter solenoid. You could always try using a jumper wire across the interlock switches if you think that they may be bad or just use an ohmmeter or a test light.

From your earlier description it sounds like the starting switch is bad, but I can't tell from the diagram just how they control the motor. The fact that the motor won't turn off when you turn the key off sounds like a bad start switch.

I suppose you could disconnect one end of the wire going from the solenoid to the starter motor and do the starter circuit troubleshooting by listening for the click the starter solenoid should make when it closes. Then with a test lead going to the plus side of the battery start at the solenoid, make sure it closes when you apply +12 volts to the control terminal and work your way back to the start switch via all the interlocks. I think that is what I would try.
 
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Old 01-15-04, 12:26 AM
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Look at the terminals on the back of the ignition switch. If one or more are very rusty, file the terminal until it is clean, or replace it. I believe, on that mower, the solenoid trigger wire from the switch is white. It will connect to the switch terminal marked "S". It should have 12v when the key is turned to start. The solenoid you have is not internally grounded if it has two spade terminals near the base. One of these terminals gets 12v when starting, and the other should be connected to ground.
 
  #9  
Old 01-17-04, 06:03 PM
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Well, you guys got me closer, but still not getting power to the starter solenoid yet. I've got 12V out of the ignition switch to the first interlock (plunger switch activated by the clutch/brake), and out of there to the next interlock (4 wires, I believe it's the the nuetral safety one?), but nothing coming out of there and nothing to the one under the seat. I've got the trans in neutral, parking brake set, and sitting on the seat. The interlock getting power to it has 4 wires, so I'm not really sure which ones to jump to see if this is the problem or not. The seat switch has 2 wires, so I can jumper that one easily. I've not tried to "hot-wire" start it yet to see if the key will kill it, too darn cold to move it outside and mess with it right now! But I'm further than I was!

Thanks for the help!
 
  #10  
Old 01-17-04, 09:30 PM
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It's impossible to tell from the diagram I printed from the Sears web site, but I suspect that the seat switch MAY do two things, it will prevent the engine from starting by interrupting the circuit to the starter solenoid, and it will also kill the engine if you fall off. That could be why you see four wires going to the seat switch.
 
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Old 01-17-04, 09:47 PM
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The seat switch doesn't have an effect on the voltage to the solenoid. If the clutch pedal switch is working and the clutch is locked down, and the blades are off and the switch to the blade pto engagement is working, it will start no matter if you are on the seat or not. If the clutch switch is working, check the blade engagement switch. If it is not letting the current through, then adjustment or replacement may be necessary.
 
  #12  
Old 01-18-04, 04:26 PM
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Success!! Got it started, and it runs great. The problem ended up being the switch for the blade engagement. And not electrical, either. There was quite a bit of side-to-side movement in the lever arm for the blade engagement, and this was letting it slip off of the plunger on the switch. The way it's buried underneath it was hard to notice. Once I adjusted it correctly, it was good to go.

Thanks much for all the help, Jughead and Cheese!! Total cost to get it running - $0.00!!!
 
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Old 01-18-04, 10:58 PM
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Great! Glad we could help!
 
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