AC 170 gas

I noticed my gages did not read power today. Put a new battery in it, thought old one was bad, didn't seem to hold a charge. I wonder if my tractor is charging now. Gage doesn't show it.Has factory alternator with the regulator under battery. What is easy way to check this out? What is most likely fix? Thanks, Tracy

First check to see if the regulator under the battery on the torque tube has a good ground,  the resistance from the bottom mounting plate of the regulator to the tube must be much less than one ohm in order to regulate and charge properly!

Can't use screwdriver, tach cable is in the way. Does show discharge with lights on. Fuel gage will not turn on or off with key. Looks like one wire at regulator is grounded to tractor frame. What do I do next for simple test? Thanks, Tracy

From the 1960's local service schools on 170 thru 220 tractors electrical systems testing:  If the system isn't charging, the first thing you do it verify the ammeter is functional by turning on the lights. If the needle dips, you can assume your ammeter is OK. Second step is to make (already have) a jumper wire to go from the "hot" post on the backside of the alternator into the square plug on the back of the alternator where the existing field wire is to excite the fields. A full 12 volts to that one (green?) wire will place the alternator into full output. If the alt charges now, you have a regulator or wiring/grounding issue. Wiring issues in those days didn't exist and maybe if the hood was removed sometimes the ground wire didn't get reconnected.  If it doesn't charge, you have an alternator issue. OEM old school regulators make a "clicking" sound when you turn on/off the key. Modern regulators don't because there are no breaker points inside these days.

I took a look at the 170 gasser today. I tried jumping the hot wire to the ground on back of alternator, no difference on ammeter gage. I did notice the only time ammeter gage moves is with the light switch on. No movement on fuel gage or water temp gage.  How many wires should go to the back of key switch? Is there a good wiring diagram of the 170 gas ? I can't find one in my service manual, can't find my operators manual.I did get a half inch of much needed rain, need much more. Any help appreciated. Thanks Tracy

Joe,I will check it. Thanks, Tracy

The ammeter is wired hot all the time, key on or off. The ignition key has no effect on the ammeter. The regulator gets fired up by the ignition key which then sends a signal to the square plug on the backside of the alternator to begin charging. That's why the jumper wire test. Good ammeter and a short jumper wire will verify the alternator charging (or not). The other gauges on the instrument panel have nothing to do with any of the charging systems function.

Ammeter works because it shows a discharge when the lights are on. 12 volts applied to the square plug wire should have put the ammeter up to 20-30 amps depending on engine speed. 99% sure you have an alternator issue at a minimum.

Yes, if the alternator is really working the ammeter will show a charge when you use the jumper wire. The regulator is out of the loop and has no control over anything.

Fuel and Water are triggered by resistance to ground. Take the temp sensor wire and ground it - the needle should peg.  Same with the fuel gauge ground the sending wire and the needle will go to full. If not check for 12v at the gauges - if both needles peg it is the senders.

Exactly as to the fuse - these unit are at the age the fuse can be good and the bottom contact corroded, the spring bad, or the wire is not making good contact or has desoldered itself from the contact at the spring.  

Thanks guys, I will check it out. Tracy