Tractor dies when key switch is returned to Run

tlbrabb

New User
JD 1010 RU - 1962 low serial number 12v system 6v coil

I have replaced the key switch with resistor twice. The coil is 6v. The first new switch was bad and had no voltage in access position.

I have attached the battery (B), ignition (I), and start (S) wires to the second new switch. Nothing is attached to the 'F' terminal or the accessory terminals. Tractor will start and run with key in start position. It dies when key returns to run. Voltage at the coil (+) is 3.5v with key in run position. Voltage at the coil (+) is 9v with key in start position. The battery is a little low but tractor starts easily and runs ok as long as key is held in start.

I have studied all of the related posts and tested recommendations, but have not found the answer to this problem. Any help would be appreciated.
 
Are you sure you are getting the correct switch? You said the first switch was bad. That brings into question that the switch supplier may have incorrect parts. Is the second switch from the same supplier? If so, who is that supplier?
 
(quoted from post at 16:24:26 05/20/20) Are you sure you are getting the correct switch? You said the first switch was bad. That brings into question that the switch supplier may have incorrect parts. Is the second switch from the same supplier? If so, who is that supplier?

Not sure I'm replying in the correct spot. I ordered key switch AR26528 Key Switch for John Deere Tractor 1010 from Reliable Aftermarket Parts, Inc. It looks right but does not have any of the letters stamped into the back next to wiring connection blades. As it tests out it seems the tractor should run on the 3.9 volts which does pass to the coil. Unless something else is telling the engine not to run???
 
Clean up all of your connections.
Especially the grounds. Check the
terminal ends. Your voltage is way low
in both positions. Should be 11 to 12 in
the start position. Should be 5 to 6 in
the run position. 3.5 isn't enough to
run on. Make sure there's 12v going in
to the switch and find where it drops.
 
Do you have generator or alternator charging system?

Does it by chance have an alternator conversion kit where someone added the extra resistor that often comes with a kit?
 
https://www.reliableaftermarketparts.com/products/ar26528-ignition-switch-with-keys

I just looked at the Reliable website. This is the switch. Looks like a bad construction job. Notice the bends where the metal pieces are crimped together. I wonder who actually makes that switch?
 
(quoted from post at 09:52:27 05/21/20) Do you have generator or alternator charging system?

Does it by chance have an alternator conversion kit where someone added the extra resistor that often comes with a kit?


No alternator. I have the tractor for at least 25 years.
 


Thank you for your advice. Only a couple of spots to check the connections but the wire from the switch to the coil may be bad/corroded. Will check if it will quit raining for a couple of days. Thank you.
 
(quoted from post at 14:47:05 05/21/20)

Thank you for your advice. Only a couple of spots to check the connections but the wire from the switch to the coil may be bad/corroded. Will check if it will quit raining for a couple of days. Thank you.

OK finally got back to working on tractor. I've cleaned all of the wiring connections, checked all of wiring, replaced regulator which was badly rusted, replaced key switch with resistor twice, put in a 12v new battery. Still I can't get more than 4.1v to the 6v coil. Tractor starts and runs fine with key in start position but still dies when key allowed back to run position. I'm stumped. Ideas?
 
Just disconnect the wire from the switch to the coil and measure the actual voltage on the wire with the switch in the run position.
If the voltage is low, remove the ignition wire from the switch and measure the resistance of it. The resistance should be next to nothing. If there is resistance then there must be another resistor inline which is causing your issue.
 
(quoted from post at 11:45:30 06/19/20) Just disconnect the wire from the switch to the coil and measure the actual voltage on the wire with the switch in the run position.
If the voltage is low, remove the ignition wire from the switch and measure the resistance of it. The resistance should be next to nothing. If there is resistance then there must be another resistor inline which is causing your issue.
====

The coil wire resistance is .5 ohms. Tried a different wire, no change.

At the negative coil post, key in run position, points closed 4.3v, points open 12.3v. Wire from coil + post runs to distributor.

Key in run position, coil wire disconnected, 12.6v at end of coil wire. No load, no current, so resistor not getting hot to reduce volts. This should be ok.
 
(quoted from post at 14:19:18 06/19/20)
(quoted from post at 11:45:30 06/19/20) Just disconnect the wire from the switch to the coil and measure the actual voltage on the wire with the switch in the run position.
If the voltage is low, remove the ignition wire from the switch and measure the resistance of it. The resistance should be next to nothing. If there is resistance then there must be another resistor inline which is causing your issue.
====

The coil wire resistance is .5 ohms. Tried a different wire, no change.

At the negative coil post, key in run position, points closed 4.3v, points open 12.3v. Wire from coil + post runs to distributor.

Key in run position, coil wire disconnected, 12.6v at end of coil wire. No load, no current, so resistor not getting hot to reduce volts. This should be ok.

Today I wired the switch directly from the battery 12.3v. With switch in run position still only had 4.3v at the coil with wire connected to coil and points closed and 12v with points open. I then disconnected the wire from coil and had 12+ volts with switch in run position. I have cleaned both ends of the wire between + battery post and grounding on engine.
 
(quoted from post at 13:57:33 06/24/20)
(quoted from post at 14:19:18 06/19/20)
(quoted from post at 11:45:30 06/19/20) Just disconnect the wire from the switch to the coil and measure the actual voltage on the wire with the switch in the run position.
If the voltage is low, remove the ignition wire from the switch and measure the resistance of it. The resistance should be next to nothing. If there is resistance then there must be another resistor inline which is causing your issue.
====

The coil wire resistance is .5 ohms. Tried a different wire, no change.

At the negative coil post, key in run position, points closed 4.3v, points open 12.3v. Wire from coil + post runs to distributor.

Key in run position, coil wire disconnected, 12.6v at end of coil wire. No load, no current, so resistor not getting hot to reduce volts. This should be ok.

Today I wired the switch directly from the battery 12.3v. With switch in run position still only had 4.3v at the coil with wire connected to coil and points closed and 12v with points open. I then disconnected the wire from coil and had 12+ volts with switch in run position. I have cleaned both ends of the wire between + battery post and grounding on engine.

Resistance 3 ohms across resistor.
 

To the question above this is a tractor with generator.
more testing today:
2.4 - 3.1 ohms resistance on coil wire
10-11 ohms across resistor
3+ ohms from switch 'B' switch post to 'F' and accessory posts

I am leaning to idea switch is wrong or bad.
 

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