285 Mf Charging trouble

[FarmerPaul]

My old 285 Mf is causing me some trouble . Replaced battery and alternator . Amp meter only show a charge after running throttle wide open ( but not always ) is there a pressure switch connected to the charging circuit ? If so where is it located . Part number for replacement

[MrSteve]

My old 285 Mf is causing me some trouble . Replaced battery and alternator . Amp meter only show a charge after running throttle wide open ( but not always ) is there a pressure switch connected to the charging circuit ? If so where is it located . Part number for replacement

No pressure switch... Voltage regulator problem?

[cornshucker]

There is a pressure switch mounted on the oil pressure guage. when oil pressure comes up this activates your electrical system the same as turning on an ignition switch on other models. If your fuel guage and tempature guage are working this switch is not bad. If this is the case it points to the exciting diode.

[FarmerPaul]

Thanks for the info . have been trying to find a wiring diagram with no luck . The temp gauge and the fuel gauge are both working . Will pull the dash and have a look . Thanks

[cornshucker]

Look on the end of the alternator and you will have 3 wires. Get a jumper wire and touch it to the battery post on the alternator(the big wire) and to the wire in the plastic connector that is marked # 1 while the tractor is running and this should excite the alternator to charging and it will charge until you cut the tractor off or the battery reaches full charge. If this is the case either the wire coming from the oil pressure switch to terminal # 1 on the plastic connector on the alternator is broken or disconnected or the exciting diode which is in this wire is bad. you can use the jumper wire until you have time to trace the wiring.