Charging Light On when Key off?

[jmann]

Just bought a nice L245DT. One of the first things I'm troubleshooting is the charging system. Tomorrow I'll confirm that the alternator is charging the system properly (seems to be). The charging light does NOT come on until the key is turned OFF. So the key is off, I pull it, and the charging light is still on. I pulled the neg. battery cable to shut the light off for now, and it clicked (around the dash area) when I did. When I tapped the neg. battery cable against the battery post, I could get the click again.

Ideas on where to start?

 

[SuperCharged]

I'm not sure of the wiring schematic, but i'd start looking for wires reversed at connections on the light, alternator and maybe key switch.

 

[jmann]

Wiring is next step. Tested battery and alternator voltage today. Battery is down a bit at 11.xx volts. When engine is running, battery has ~12.55 volts (slightly inconsistent voltage--perhaps belt slippage). I'll tighten the belt and see if this doesn't increase.

 

[kuboman]

Wiring is next step. Tested battery and alternator voltage today. Battery is down a bit at 11.xx volts. When engine is running, battery has ~12.55 volts (slightly inconsistent voltage--perhaps belt slippage). I'll tighten the belt and see if this doesn't increase.

Sounds like you either have a alternator with a short or the voltage regulator is shorted.
Do you have the dynamo or regular alternator?

 

[Eric McCarthy]

Is there a battery shut off switch or kill switch on the dash? I have a B6100E and mine has a switch on the dash to shut power off from the battery.

 

[Marty394]

Could have an open diode in the alternator causing a back feed.


Bob

 

[jmann]

**UPDATE**

Replaced regulator and problem persists without change. I'll describe a few things, though, and hopefully we can narrow down the problem:

With new regulator, alternator is still not putting out much of a charge (~12 volts at best).

Even when the engine is NOT running, the charging light is ON when the key is OFF, and the charging light goes OFF when the key is turned ON. Backwards!

With key OFF, disconnecting neg battery cable makes the regulator "click" off (and charging light goes off)--No surprise.

With key OFF, disconnecting the plug (pictured below) in the alternator (dynamo? what's the diff?) makes the regulator "click" off (and charging light goes off).

The same thing happens (when the plug is removed from the alternator) even when I ground the regulator directly to the neg. battery terminal and disconnect the regular cable from the neg. battery terminal (not sure if this means anything).

I grounded the free post on the alternator when the key was OFF and it did click the regulator off.

Could this just be a wiring reversal at the key switch? As far as I've searched, I have not founding any wiring problems, shorts, or burnt plugs.

 

[jmann]

BTW, here is a wiring diagram in my operator's manual:

 

[Kubota Newbie]

Make sure that the wires to the fuse block are all in the correct order by color and position on both the in and out sides of the block. Had the same problem on my M4500 when I bought it last fall. Turned out to be a wire out of position on the fuse block. At least on the M5400 some of the terminals are connected by a buss bar on the back side, can't see that from the front, drove me nuts trying to figure it out and it was just a reversed wire.

 

[jmann]

Did some searching around the net and found a similar story on a 245DT and the alternator seemed to be the fix. I think Marty394 is right: a bad diode is allowing back feed--this explains why the charging light is on when the key is off and why disconnecting the alternator plug turns the charging light off. I still am not sure why turning the key on would cause the charging light to go off when the engine is not running. Any other ideas before I replace the alternator? (it is old enough that I won't feel too bad replacing it, even if it isn't the culprit).

 

[Theekillerbee]

If you can, try to find a local rebuild shop that can fix it for you, as it is much cheaper than new. Around here, you can usually get alternators/generators rebuilt for around 60 bucks.

 

[firejunkie]

I'm willing to bet bet it's in the key switch.

 

[jmann]

If you can, try to find a local rebuild shop that can fix it for you, as it is much cheaper than new. Around here, you can usually get alternators/generators rebuilt for around 60 bucks.

I found two new aftermarket ones for around $75 + shipping.

http://cgi.ebay.com/ebaymotors/Case...ccessories&hash=item20b59f5870#ht_2509wt_1182

Mowpart

 

[jmann]

I'm willing to bet bet it's in the key switch.

For the key switch to be the problem, I think there would have to be a positive connection when the key is in the OFF position. In other words, something is wired to turn ON when the key is OFF, but I can't think that the key switch closes any circuits in the off position.

I assume that in the OFF position, all circuits are open, i.e., no power is running through the electrical system. For a test, I started the tractor and tested voltage at the battery. With the key ON, voltage was 12.xx (that's all the alternator is putting out), when the key was OFF, voltage dropped to 11.xx (which I interpret as shutting off alternator charging).

So I suspect the alternator is both weak and has a bad diode that is allowing battery current into the electrical system backwards. If this is true, my remaining question is why the charging light goes off when the key is turned ON but the engine is not running.

Am I missing something? Getting close to pulling the trigger on a new alternator.

 

[ipz2222]

I would suspect a bad alternator also but mainly because the batt voltage is not high enough. Eng off and running...

 

[jmann]

New alternator solved it as suspected. On to other projects!