MF 175 Key Switch

[bigtom63]

Recently replaced the alternator, Battery and key switch. When the battery is fully charged it starts just fine but while running the alternator gauge shows on neg side without lights on and really on neg side if lights are on. After using tractor for an hour or so put it back in barn and turn key switch to off and it will not turn off. Turn it the other way and can hear the starter trying to engage. What could cause the key switch not to shut tractor down. Where should I start troubleshooting?? After plowing snow I put battery charger on tractor and it shows that the battery is very low and needs charged.

 

[Anonymous-0]

think these had an oil pressure switch deal on them maybe in the guage.

 

[Tom Dold]

bigtom63

It depends if the tractor is gas or diesel or if the tractor was originally equipped with a generator or an alternator. They were equipped with either depending on serial #. If a later style Delcoe (self contained regulator) alterntor was put on a gas tractor the excite wire must have a blocking diode to prevent the alternator from feeding back to the ignition coil. If it doesn't the engine will not shut down and depending where the excite wire is being fed from could cause the starter solenoid to engage.

Tom Dold
Dold Implement
201 S. Main St.
PO Box 70
Howard, SD 57349
605-772-4541
[email protected]

 

[bigtom63]

First off it is gas and I replaced the alt/gen by using the number on the old unit and converting it to a newer number. If I get the new part number can you tell me what I may have to do or is their a easy way to test measure somewhere I do have a digital multimeter

 

[El Toro]

Your alternator is probably backfeeding voltage to your ignition. You need to install a diode as shown in Bob's diagram. This will stop the back feeding. Hal