John Deere 4020 Electrical Problem

John Deere 4020 Electrical Problem Problems

Hi everyone,

I have a problem with my John Deere 4020.

This last summer – if the tractor sat for more than 2-3 days … that will not start. At that time – it was a 24V system.

The first thing I did was replace the battery – 2 new JD 12V.

He seemed to help for a while – but not for a long time and did not start again if he sat for more than a few days.

After many suggestions to change the tractor to 12V- I bit the bullet and bought the kit. The change did not seem to have any problem. I followed the attached instructions. I connected the batteries in parallel (the two positives to the boot engine and the two negative to the tractor frame).
The same – Accept apparently worse now. The tractor stays one day … and it does not start. HMMM
I started solving some problems.

I connected a load tester. Both batteries show 12-13 volts after a load. I disengaged the clip of the red / white cable that goes to the alternator – checked with the test light ….. red = light, and white = dim light. To my understanding – with the key shutdown …. My white cable must be dead. So it seems to have some dispersed tension here?
I approached the key – all peaks on the back are used. 3 of the 5 are hot with the key off. (one is a little more tenuous than the others)
Does this tell someone to someone? I have no idea where to go next … but you are getting tired of having to push each time I need to start the tractor. (Boot every 3-4 days to fill a hay feeder)
Thank you for any information.

John Deere 4020 Electrical system

Check the switch with an ohm meter. You will have to unplug the cables to do so. The switch could be bad. I had one that broke down in a 3020 and exhausted the battery in a short time.

Take the battery cable to take a Volt meter from the Post to the cable to see if you have a reading with everything it was. If so, you have the short circuit or ground flow. If you go to the fuse panel, you start removing the fuses until you find the short circuit, then that is the circuit in which you have to work. Alternator may not have a fuse not all make it disconnect the battery cable out or the alternator feel after the tractor and fresh sets to see if the alternator is the worm.

Do you have a light or a meter to know if the alternator is working?

I have a test light, a load tester – and an ohm meter that I do not use very often (not very sure how to use it).

I tested the alternator through putting my charging tester in each of the batteries with the tractor running. He showed 14.2V on both sides. I think the alternator is fine.

Do you want me to put my voltmeter between the POS cable and the pole (with the unmanned cable)? Can I try that – should read zero? In what position should I have my meter to do this?

I have checked one of our white cable must be dead with the key off. There should be a cable from the switch to the generator light and then from the generator light to the white wire in the ALT connection. When the ALT begins to load the white cable loses its land from the regulator and the gene light goes off. It seems to me that that switch is wrong.

That is a good idea about the connection between the POS cable and the post. I only use a test light, most of those meters are so sensitive that they capture the voltage in one that is working well.

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