The point of this post, is to aid in quickly identifying why an alternator may not be charging. Basically we will test to confirm that the alternator is receiving it's "turn-on" signal. Information may be added as posters run into different situations. Note, alternator will not charge if the instrument cluster is not active. Tools Needed: 1 Volt meter w/ resistance and DC functions (can use 2 volt meters) 3 Small alligator clips 3 Straight-pins (insert at an angle to probe through wire insulation) Identify Alternator Connections: 3-Pin Wire Harness X - Thicker gauge white-green wire (Constant 12v) Y - Thinner gauge white-green wire (no resistance to ground) Z - Thinner gauge white-black wire (0v with ignition off, resistance to ground, switched to 3v w/ ignition on) Single Bolt-On Wire Very Thick gauge Black-White wire (Constant 12v) 1-Pin Wire Harness Thinner gauge white-green wire (responsible for deactivating dash cluster battery light) Preparation: Using volt-meter, ignition off, identify/confirm the function of each wire; which delivers 12v, 0v, ground. Confirm that there is resistance to ground on the 0v. Do not make assumptions as wiring color/function may vary from year-to-year, manufacturing plant to manufacturing plant. Testing for Regulator Turn-On Signal: 0) For the following, leave the negative probe connected to alternator casing. 1) Turn the ignition to Run. (no need to start engine) 2) Wire Z should now read positive voltage. (3v in my case) 3) Turning the ignition back to Off, should show it switching back to 0v. If the wire does not go positive, then the problem might be somewhere further up in the circuit. A *factory* manual will be required to help identify and pin-down all the possibilities. Haynes/Chilton circuit diagrams are not detailed or precise in this regard. With the engine running and monitoring for change at the battery or bolt-on wire, you can manually apply voltage to the Z wire and see whether the alternator will start charging. If the wire went positive but still did not charge until you manually applied voltage, the issue could be that the voltage on the turn-on signal isn't high enough to trigger the regulator. If your "Z" wire circuit is weak/faulty and require help with the circuit, let us know. I don't have a factory manual, but there are those here that do. =================== Backstory: Pretty much my own fault, but had to have it towed for the first time ever, early last week. ($180 tow.) The reason it's partly my fault, is because I procrastinated and procrastinated on replacing the corroded connector on the single-wire harness for the white-green monitoring wire on the alternator. This meant I was getting the alternator light most of the time. Last weekend I got to testing it. I started it up, and it charged a stable 14.3v. Revved the RPMs and it would quit charging. Dropped back down to idle and it charged. I repeated this for a good five minutes before it quit charging altogether. My alternator charging was in effect, intermittent. This means that it passes bench testing at the auto parts stores. Alright, picked yet up another alternator and installed it, only to find it wouldn't charge at all. This would make number three since reluctantly turning my OEM in as a "core" part at ~260k. (I'd still be running on it if I hadn't ignored the squealing from the worn-out brushes.) These steps helped me determine that the third replacement was D.O.A.. Well, I'm taking it back and will instead, just get a BWD brand regulator assembly, to be inserted in my second replacement. Amazing how I could be on my fourth alternator in ~60k, until you consider the total lack of quality in replacement parts. I'm not interested in a "lifetime" warranty, I'm only interested in quality parts that don't cost me time and more money.