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Fieldtech59
Fieldtech59, Shop manager
Category: Construction and Road Equipment
Satisfied Customers: 111
Experience:  Construction equipment repair technician since 1986, JLG certified, Shop manager since 2006.
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I have a problem with a 490E deere excavator the alternator

Customer Question

hi I have a problem with a 490E john deere excavator the alternator stopped charging and the batterys got drained so I charged the batterys with a charger on each battery and then tried starting it the same way it would not turn over and some of the warning lights and alarm stay on with the key off I have to unhook the ground on the battery to stop them
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  Curtis B. replied 1 year ago.

Do you have a voltmeter to test the battery voltage? Fully charged battery would be over 13 volts. What does each battery show? You may find that you have a bad battery and not a bad alternator.

Customer: replied 1 year ago.
This happened after replacing both batteries.
Expert:  Curtis B. replied 1 year ago.
Have you checked battery voltage? Yo said you ran batteries down and then recharged them. Maybe one did not get charged?
Customer: replied 1 year ago.
just replaced them last night. Same thing.
Expert:  Curtis B. replied 1 year ago.
Ok,let me opt out and see if any of the Deere guys are up today. Sorry I can't help.
Expert:  Fieldtech59 replied 1 year ago.

I can't say for certain it's your problem, but have you addressed the issues that the alternator has? I'm not certain about the 490E (basically a yellow painted EX120 Hitachi) but many Deere excavators used a voltage feedback wire to an anti re-start relay. The way it works, once the engine gets running the alternator starts putting out voltage, it then sends a voltage signal to trip a relay that prevents you from accidentally engaging the starter once the engine is running. If an alternator set up like this were to go poof just right inside it could drain the batteries with engine not running (rectifier failure) and could make a direct connection from batteries to the anti restart relay via the fried alternator.

If this is the case, try disconnecting all the wire connections to the alternator and see if the engine will crank then.

Customer: replied 1 year ago.
disconnected the wires still nothing and the warning lights still stay on when the key is turned off until disconnecting the ground from battery
Expert:  Fieldtech59 replied 1 year ago.

Well, it was worth a shot. I'm not sure what's happened to this machine with the events that you described, i.e., alternator stopped charging, batteries went dead, charged batteries, now won't crank and warning lights stay on when key is turned off. It sounds like something is keeping the battery disconnect solenoid powered up when you turn the key to OFF, and the battery disconnect solenoid is controlled (on/off) by the main controller (ECM) mounted behind the operators seat. And if, for whatever reason, the main controller is confused in controlling the battery disconnect solenoid, it's very possible your "won't crank" problem is related to the main controller problem as well. That's the part I can't explain, what has happened to the main controller because of a "alternator quit charging" situation, and troubleshooting a main controller is a tricky thing to do, not much there a person can test with a simple test light, pretty much requires a tech plugging a laptop into the data link. Not much else I can offer, I'll opt out of the question and see if anyone else has any ideas. I hope you get your problem sorted out. Cheers

Customer: replied 1 year ago.
I am requesting a refund. The experts were not able to help me. I have decided to call a mechanic to look at it. Please refund my card as soon as possible. Thanks for your time.

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