My alternator died on my 94 Ranger 4x4 so I got a used one a few days ago installed it and get no charge, so I got another one from a junkyard tonight and still it's not charging, both could be bad but I'm not sure. After hooking up the 1st one I did not get the low battery light with the key on/ engine off, now with the 2nd one I do get the battery light on the dash so I assume the 1st was bad, but not sure about the 2nd. I have 12v at the wire that bolts on the back of the alt. and on the plug (3 wires) I get 12v/0v/5v........is there any way to check the alternator on the truck other than at the battery? When the truck is running I get 12.38v and with it off I have 12.58v...........Any help would be appreciated..........might have to take it to AutoZone and have it checked. :(

 

Get it checked. All your voltage readings sound right

 

Had it checked at AutoZone and it passed the tests, still no charging, checked the voltage again with key on/ engine off 12v at wire bolted on back, 12v on 2 of the 3 wires that are on the plug, center wire has 0v, battery light stays on all the time........any ideas why I am getting no charge?

 

Found a small hole in the casing of the Y/W wire where that wire started to corrode, it had 12v to connector with key on/ engine off but only 1.9v when engine was running , spliced the wire and the alternator is working again.