Gocart879,
My suggestion still stands about help from a qualified auto electric man. If you are bound and determined to test 'something' here is a recipe from my Motors manual for Leece-Neville alternators...no guarantees!
As with all alternators, the field must be 'excited' for the unit to start charging. Basically, if you turn the key on , engine off , and pull the field wire off the regulator, then 'scratch' or strike that same regulator terminal with the wire, it should show a medium spark. This means the circuit in the regulator is closed and power is available to excite the alternator.
Turn the key off and replace the wire. To put the alternator into full field charge, with everything turned off, pull the field wire (F) from the alternator and hook a jumper from that F terminal that you will momentarily touch to the BATT terminal of the alternator.
If you start the truck (fire engine), and touch that jumper to the BATT terminal, the alternator should go into full charge. You will need a functioning ammeter, or a test voltmeter to see this happen. If this does happen, it tells you your alternator is capable of charging.
This of course would point the guilty finger somewhere else.
I am not sure where a impact wrench comes into the test picture, but if this is a skill level indicator, it might be cheaper to take the old girl to a proper Dr.
Good luck and don't let the magic smoke out!
Stuart
