I have a 1999 B7300 with an illuminated battery warning/generator warning light when running. Hours on the tractor are 366. I replaced the dynamo and still had the light while running. The old dynamo was noisy enough to be heard over the motor when running. I opened the dash,got into the voltage regulator and found a wire broken at the plug so I replaced the voltage regulator. the six contact plug was clean and dielectric grease applied. I've replaced all three fuses and cleaned all contacts. Also cleaned the 30 amp fuse contacts. The fuse was good. Still the light when running. Any suggestions?
Battery Warning Light/Generator Light
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85Hokie
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BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Place a volt/ohm meter on it .....without starting, notice the voltage, then crank, idle= how many volts? 1/2 throttle = volts? WOT =volts????
record and report back.
record and report back.
85Hokie
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Lifetime Member
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BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Lets back up a second.....
your digital meter reads 12.26 with engine off..... and idle and WOT?
turn lights on....should drop.....
but if all that is true - you are not charging 12.26 is low......
My apologies for not responding sooner. Family emergency. I disconnected the dynamo at the wiring harness and ran the tractor. According to my digital meter I am getting 9.2 volts at idle and 19 volts at WOT. I found a Kubota manual on line and the no-load voltage at the dynamo leads should be 14-15 volts and at higher speeds it should be 36-39 volts. The numbers were hand-written with PSB-2000-005 annotated and 3-2-06 written below that. Guessing some sort of product service bulletin.
North Idaho Wolfman
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Leave the 2 wires from the dynamo hooked up to the harness to check your charging system.
To test the dynamo, unplug the 2 wires, set DVOM to AC volts and read it. You're looking for about 37-39 volts at rated engine RPM (full throttle). Dynamo's are real simple. They rarely fail, and when they do it's usually the bearings...easily replaceable (and cheap).
Back to the charging system. This system is an external voltage regulator. You'll have I think 5 or 6 wires (most are 5). 2 go to the dynamo. 1 goes to the battery (hot all the time). One is ground. The other goes to key switch, hot in run position only.
It is not common for regulator to die, and they are kubota-only parts, and a little expensive so you'll test AROUND the regulator before deeming it "bad". In other words, at the connector you'll find a single red wire, usually 2 blues or whites (they are 2 of the same color, those go to the dynamo), a white/red and a black. If you have a manual, you may find that it's showing different colors at the regulator connector. You'll want to test the 2 wires that have the same color, engine running, connector disconnected, and test for AC voltage at the harness side of the connector. Should be the same, or very close to what you saw at the dynamo. Then test for +12v, key off, at the battery wire (usually red but not always). Then test to see if the trigger wire is seeing +12v from the key switch in the run position only. And finally check for a GOOD ground (0 ohms between the ground wire and a bare bolt or the tractor's chassis). If all those tests end up "good", your regulator is "bad". If one of those tests is bad, find out why...usually wiring harness problem or a key switch problem, most commonly in our case, harnesses and connectors get corroded.
Again all those wire colors are off the top of my head, so be sure to check your wiring diagram. Sometimes the dynamo wires at the regulator connector are yellow.
To test the dynamo, unplug the 2 wires, set DVOM to AC volts and read it. You're looking for about 37-39 volts at rated engine RPM (full throttle). Dynamo's are real simple. They rarely fail, and when they do it's usually the bearings...easily replaceable (and cheap).
Back to the charging system. This system is an external voltage regulator. You'll have I think 5 or 6 wires (most are 5). 2 go to the dynamo. 1 goes to the battery (hot all the time). One is ground. The other goes to key switch, hot in run position only.
It is not common for regulator to die, and they are kubota-only parts, and a little expensive so you'll test AROUND the regulator before deeming it "bad". In other words, at the connector you'll find a single red wire, usually 2 blues or whites (they are 2 of the same color, those go to the dynamo), a white/red and a black. If you have a manual, you may find that it's showing different colors at the regulator connector. You'll want to test the 2 wires that have the same color, engine running, connector disconnected, and test for AC voltage at the harness side of the connector. Should be the same, or very close to what you saw at the dynamo. Then test for +12v, key off, at the battery wire (usually red but not always). Then test to see if the trigger wire is seeing +12v from the key switch in the run position only. And finally check for a GOOD ground (0 ohms between the ground wire and a bare bolt or the tractor's chassis). If all those tests end up "good", your regulator is "bad". If one of those tests is bad, find out why...usually wiring harness problem or a key switch problem, most commonly in our case, harnesses and connectors get corroded.
Again all those wire colors are off the top of my head, so be sure to check your wiring diagram. Sometimes the dynamo wires at the regulator connector are yellow.
Thanks for the help. I did measure the voltage using AC. Looks like the replacement dynamo is bad. Also pulled the voltage regulator and discovered one of the wires from the regulator was burned at the terminal connection and separated from the connector. I ordered one regulator, it did not work. Second regulator same song. Looks like your comment about proprietary is correct. I downloaded a Kubota manual and tested the continuity of the two new regulators and they did not match the specs. I tested the original regulator and it passed the continuity test but I have one wire that is disconnected from the 6 pin terminal. The blade was corroded and fell apart when I disconnected the plug. If I could somehow attach the wire to the terminal block with a blade I could use the original regulator. Returning the replacement dynamo and waiting for the new one. When I had the regulator disconnected I tested the dynamo voltage at the 6 pin connector into the regulator and voltage results were the same.