Matt_Jr
Platinum Member
First you'll need to check to see if the wire to the alternator is still good. Hope you've got a multi-meter. Check resistance between B+ and the alt B+ terminal. Next check resistance between alternator housing and ground on the battery. Both should be near zero or less than .3 ohms. If ok test the alternator and diodes. Start by checking charging voltage.
1) Start tractor and run at rated rpm. Set voltmeter to DC and connect it to the battery, should be around 13.7 volts. If voltage is ok go to step 2. If not go to step 3.
2) Check the diodes by switching your meter to a/c voltage and measure voltage at the battery again. This time it should be less than .5 volts. If voltage is higher replace alternator.
3) Shut off tractor and connect a jumper wire to your "F" terminal on the back of the alternator and the B+ side of the battery or B+ terminal on the alternator. Start tractor and run at rated rpm. Measure voltage at battery. Should be around 13.7 volts. If it isn't you need an alternator. If it is around 13.7 switch your voltmeter to AC to test diodes. You should read less than .5 Volts. If under .5 volts alternator diodes are good. If not the diodes in the alternator are bad. If both of those tests are ok you'll most likely need a regulator. This part is time consuming, but using the wiring diagram supplied by JB4310 check the resistance in the rest of the circuit(each end of each wire of the regulator and alternator with negative battery cable disconnected). This will make sure none of the other wires have melted somewhere, causing you to buy an unneeded part. let us know how it works out. Good luck.
1) Start tractor and run at rated rpm. Set voltmeter to DC and connect it to the battery, should be around 13.7 volts. If voltage is ok go to step 2. If not go to step 3.
2) Check the diodes by switching your meter to a/c voltage and measure voltage at the battery again. This time it should be less than .5 volts. If voltage is higher replace alternator.
3) Shut off tractor and connect a jumper wire to your "F" terminal on the back of the alternator and the B+ side of the battery or B+ terminal on the alternator. Start tractor and run at rated rpm. Measure voltage at battery. Should be around 13.7 volts. If it isn't you need an alternator. If it is around 13.7 switch your voltmeter to AC to test diodes. You should read less than .5 Volts. If under .5 volts alternator diodes are good. If not the diodes in the alternator are bad. If both of those tests are ok you'll most likely need a regulator. This part is time consuming, but using the wiring diagram supplied by JB4310 check the resistance in the rest of the circuit(each end of each wire of the regulator and alternator with negative battery cable disconnected). This will make sure none of the other wires have melted somewhere, causing you to buy an unneeded part. let us know how it works out. Good luck.
