184 will not shut off with key

J

Justbarf

Active member
Hello everyone,

I am at a loss. I am fixing up a 184 lo-boy. I just took out the engine and replaced all the seals and gaskets. I put everything back together and the tractor cranked up like a champ, but when I went to turn the tractor off, it stayed running. I even took the key out and it staying running. The only way to kill the tractor is idling down and choking it out. Now if I disconnect the alternator, the tractor will shut off with no problem. I replaced the resister on the alternator to see if that was it, but that didn't fix the problem. I am not sure if the problem is in the ignition or in the alternator. If anyone has ran in to this problem and know where to begin that would be great.

Best,

Justin
 
Electrical wiring problem. Alternator is back feeding the ignition system.

Typically, when this problem occurs, the wire from the #1 alternator terminal is not disconnected when the ignition key is off.
 
Finally got around to putting in a new ignition switch and of course that did not fix the problem. I am still at a loss.
 
Reread Jim's and outdoors' advise. I don't have an alternator so your particular ignition switch may be different than 90% of them. Your alternator is still charging the ignition system someway, as Jim said.
Positive note; i commend you for the work to make the engine run well. You will be very happy with it. This is a small hurdle. There could be two wires melted together in the wiring harness but you will find it before getting too anxious and risk your work.
Just because a connector socket "fits" doesn't mean the switch is doing the same thing.
 
Thanks. I will try and look through the wiring today. I'm so close to getting this tractor running good, I'm just self taught! This is my first tractor project.
 
Check the wiring to the exciter resistor. With key off there should be 0 volts. With key on there should be battery voltage.
 
One quick test: Disconnect the two pin plug from the back of the alternator. Then see if it starts and shuts off normally. If so, your alternator is not wired correctly. Is the resister on the back of the alternator original or is it a parts store item? If the original resister is replaced with a generic ignition ballast resister (they look the same) it will cause your problem. The correct one has a much higher ohm value.
 
Larry - There is zero volts when the key is off and on the exciter resister.

Gary - When I unplug the two pin plug, the tractor cranks and shuts off correctly. The exciter resister is the correct one, glad to know I cannot just buy one from the auto store.

Does anyone know my next train of action?
 
You may have a defective regulator in the alternator. 2 of the wires from the alternator connects to the battery. The other is the exciter resistor that receives battery voltage from a connection at the ignition coil. This provides a voltage to excite the alternator and start charging. If the resistor has voltage on it when you turn the key off with tractor running it will feed the ignition and keep tractor running. Parts to replace regulator chip and diode trio are cheap. It is a standard GM 10si Delcotron alternator. GM made millions of them.

https://www.google.com/url?sa=t&source= ... JQuoNyAUbp

Here is a link to service manual for 10si Delcotron.

The big wire and the one not with the resistor should be connected to battery positive. The small wire goes to one side of the ammeter. The big wire is either connected to battery positive or at the starter relay. The wire with the resistor goes to the ignition coil to pickup 12v when key is turned on.
 
I don't think anything in the alternator can cause this, it's got to be backfeeding through the resister. Check the resister with an ohm meter, it should be a fairly high reading. Typical ballast resisters will read 1.2 - 2 ohm for example. I don't know off hand what the value should be but likely 20 - 30 ohms. Another easy check!
 
Just a thought, since you removed the engine, you probably disconnected several electrical connections. And I'm assuming that the tractor started, ran, shut off correctly prior to the engine removal.

Perhaps, an electrical connection miswired.
 
With the key off there should be 0 volts at the + term of the ignition coil. With tractor running measure voltage at + side of coil and turn key off. Is there still battery voltage at coil? If so tractor will stay running. There should be 2 wires going to that terminal. One from ignition switch and the other goes to the alternator exciter resistor. One of them is keeping voltage to the coil. If the wiring is correct. If the wiring has been changed. Good luck.
 
Justbarf":2avhu75c said:
Larry - There is zero volts when the key is off and on the exciter resister.

Gary - When I unplug the two pin plug, the tractor cranks and shuts off correctly. The exciter resister is the correct one, glad to know I cannot just buy one from the auto store.

Does anyone know my next train of action?
Click to expand...

You have alternator voltage providing power back into the coil. Look at the light green wire that runs from the alternator to the ignition coil. I have attached a wiring diagram PDF for the 184. I am guessing that this wire is connected to the wrong side of the alternator resistor (internal)
View attachment 184 Wiring.pdf
 
The resistor is on the back of the alternator. It should measure approx 10 ohms. The resistor performs the same job as the ALT idiot light on older cars. With key on and engine not running there will be current flowing from the ignition switch through theresistor and alternator to ground. This would cause the idiot light to light up. With engine running there is voltage coming out of the alternator that balances the voltage to the resistor. This caused the idiot light to go out. You can replace the resistor with a 12v bulb and it will act just like the idiot light cars had in the 60's and 70's.
The voltage applied to the resistor provides energy to excite the alternator and beging charging. When the voltage is removed from the resistor the alternator should stop charging.
 
Larry B":1rltl139 said:
. . . When the voltage is removed from the resistor the alternator should stop charging.
Click to expand...
You were right on until you got to this point. The voltage through the resistor is only needed to get the alternator started. Once it begins, it loops some of the output back to keep it going. It is this looped back output that is keeping the engine running with the ignition switch off.
 
I just went out and checked my 184. Key on i get battery voltage at the coil. Start engine i get charging voltage at the coil. Turn key off and voltage at the coil goes to zero and tractor turns off. If it stayed charging the engine would not shut off. Removing the voltage to the exciter resistor stops charging. I need to corrrect myself. The resistor is a 25 ohm not 10 ohm. Wrong vehicle.
 
Larry B":3l38ntv0 said:
I just went out and checked my 184. Key on i get battery voltage at the coil. Start engine i get charging voltage at the coil. Turn key off and voltage at the coil goes to zero and tractor turns off. If it stayed charging the engine would not shut off. Removing the voltage to the exciter resistor stops charging. I need to corrrect myself. The resistor is a 25 ohm not 10 ohm. Wrong vehicle.
Click to expand...
No. The resistor is what lets the engine shut off. Try putting a jumper around the resistor and see if it will shut off.
 
I just order a new excite resister from Hamilton bobs. I put it on, trying to weed out simple stuff first before i remove the alternator, and no change in trying to shut down the tractor. I looked at the wiring and still cannot find where anything is wired wrong. Could the ignition coil be wired wrong? Meaning could I have this wired backwards. If these were wired wrong could this then back feed from the alternator? If this is not correct, my next step would be taking off the alternator and seeing if something is wrong internally. My next step after that would be replace the wiring, because every wire is red making it hard to trace a wire when it goes into the thicker sleeved bundle.
 
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