LiLHustler620 Posted March 28, 2015 Report Share Posted March 28, 2015 1984 720 ST 4x4 Z24 5speed manual. Suddenly my battery light came on and shortly there after it drained completely. The Alternator tested bad and I replaced it. Ever since then the Alternator doesn't really charge the battery. I have check all the obvious things. Battery is definitely good. Terminal ends have been replaced. All connections have been checked and are tight. The truck runs with the battery disconnected. Voltage across the battery reads 12v. Voltage across the battery while running is around 13. Is that enough to charge the battery? Here's the strange thing.. If the headlights are on the voltage across the battery while running drops back down to 12 which is when my battery is draining which makes sense cause it usually dies at night. What am I missing. Battery good alternator good but battery still not charging. When fiddling with the Alternator wires I did break the condenser wire plum off. Could a bad condenser wire cause any issue? Like maybe ground out the Alternator somehow? I'm stuck. Suggestions please!! Quote Link to comment
datzenmike Posted March 28, 2015 Report Share Posted March 28, 2015 Nissan alternators are about $300 so a $50 'rebuilt' form China is likely your problem. These can approach a 50% bad in the box rate. If you got that useless 'lifetime warranty' have it tested elsewhere, take it back and complain. Maybe the next one will be better. Charge when running should be mid 14 volts. Quote Link to comment
LiLHustler620 Posted March 28, 2015 Author Report Share Posted March 28, 2015 Thanks for the reply. I will have the Alternator tested. Hopefully that is the problem. One more little tid bit that I find strange.. if I unhook the fusable link wire from the battery and test the voltage of the Alternator that way with the negative lead on the negative batter post and the positive lead on the end of the fusible link wire (But not connected to the battery) it shows 15 volts. So the Alternator has 15 Volts but when you connect it to the battery it drops way down. Maybe I'm looking to hard for a problem that doesn't exist. I guess I should just go get my alternator tested. I have a feeling something else is going on though. Quote Link to comment
LiLHustler620 Posted March 28, 2015 Author Report Share Posted March 28, 2015 I also have other electrical issues like when I turn the headlights on the brights come on and stay on for several minutes without reason. Sometimes I have to play around with the switch a whole lot to get them to switch back to low beams. There is also that beeping noise that happens when you turn the ignition on.. well that doesn't sound off on time anymore. It's delayed. Like it either doesn't happen at all or I'll be 10 minutes into a drive and then all the sudden it starts beeping. I only bring these issues up in the off chance that they are related somehow. That and they are extremely annoying. Quote Link to comment
LiLHustler620 Posted March 28, 2015 Author Report Share Posted March 28, 2015 One more question. Should you be able to reach down and turn the Alternator by hand or does that mean the belt is not tight enough? I've been curious if maybe I simply didn't get enough tension on the belt. I know I did NOT replace the belt. As it didn't look to bad. I think I will do that now just because. Quote Link to comment
datzenmike Posted March 28, 2015 Report Share Posted March 28, 2015 lol, no the belt has to be much more tighter than that. Quote Link to comment
ggzilla Posted March 28, 2015 Report Share Posted March 28, 2015 Don't replace the belt , just tighten it. Should have 1/2" up-and-down play. 1 Quote Link to comment
LiLHustler620 Posted March 29, 2015 Author Report Share Posted March 29, 2015 Well It's as tight as it can be. The slide bolt on the Alternator is maxed out. It doesn't get any tighter. The voltage while running was a little better this time. About 13.6. But when you turn the headlights on it still drops back down to 12 or slightly under. Quote Link to comment
LiLHustler620 Posted March 29, 2015 Author Report Share Posted March 29, 2015 If I just look at the on board voltage meter that came factory in the center console it always looks good and like its charging until you turn the headlights on and then it steadily drops off until the vehicle power completely cuts out, even while driving. Quote Link to comment
LiLHustler620 Posted March 29, 2015 Author Report Share Posted March 29, 2015 Although the tension on the belt is maxed out I can still turn the Alternator by hand. Not very easily but I can. Maybe a new belt would be stiffer and create more tension Quote Link to comment
ggzilla Posted March 29, 2015 Report Share Posted March 29, 2015 The wring belt is on there. They don't stretch that much. Quote Link to comment
LiLHustler620 Posted March 29, 2015 Author Report Share Posted March 29, 2015 The Haynes manual says I can check the regulator by grounding the brushes and turning the ignition on and seeing if the battery light comes on. Can this be done without removing the rear cover to the alternator? The diagrams are less than specific Quote Link to comment
ggzilla Posted March 29, 2015 Report Share Posted March 29, 2015 No need. If you are getting more than 13.5 and less than 15v, it is regulating. Quote Link to comment
LiLHustler620 Posted March 29, 2015 Author Report Share Posted March 29, 2015 Any ideas on why the battery would drain while headlights on? Quote Link to comment
620Turbo4X4 Posted March 29, 2015 Report Share Posted March 29, 2015 Thanks for the reply. I will have the Alternator tested. Hopefully that is the problem. One more little tid bit that I find strange.. if I unhook the fusable link wire from the battery and test the voltage of the Alternator that way with the negative lead on the negative batter post and the positive lead on the end of the fusible link wire (But not connected to the battery) it shows 15 volts. So the Alternator has 15 Volts but when you connect it to the battery it drops way down. Maybe I'm looking to hard for a problem that doesn't exist. I guess I should just go get my alternator tested. I have a feeling something else is going on though. Never test a alternator this way. The output has to be connected to a battery at all times. A "good working" alt should have shown over 20v., smoked the windings and burned itself up rather quickly. As datsun mike stated the failure rate on remans are teriable. I went through 13 alternators on a 620 I had years ago before I got one that worked for more than a week. Ideally you want 14-14.7v to adequately charge a battery. Sound like a bad alt to me. To check the wiring measure voltage at back of alt with engine running, lights on, etc... You should have the same voltage on the output as you have at the battery terminals. Any ideas on why the battery would drain while headlights on? Probibaly a bad rectifier, not regulator. Quote Link to comment
ggzilla Posted March 29, 2015 Report Share Posted March 29, 2015 Any ideas on why the battery would drain while headlights on? Yes, if the belt is loose, the extra load will slip. Tighten the belt properly. Quote Link to comment
LiLHustler620 Posted March 29, 2015 Author Report Share Posted March 29, 2015 Ok so, I went ahead and got a new alternator. I installed it and charged my battery while doing so. After hooking everything back up I started up the motor and was pleased to see that the voltage while running was right around 14.5 v. I turned the headlights on and checked voltage again and it stayed the same. No drop. Problem solved right? Well then I go take her for a spin and run the headlights for a while and when I come back and check the voltage again 15 minutes later it's back down to 12+ v when running with lights on and when I turn the lights off it very slowly climbs back up to just barely over 13v. I thought I had solved the problem with the new alternator but now I'm even more confused. Quote Link to comment
LiLHustler620 Posted March 29, 2015 Author Report Share Posted March 29, 2015 I'm not sure if my good voltage readings were the result of my fresh new alternator or the surface charge from my freshly charged battery. Could something be shorting out my alternators? I just don't understand what's going on. The ONLY straight forward thing I have left that I can do is replace the belt. The old belt is adjusted as tight as can be but maybe it is worn to the point of slippage. I don't hear any belt noise and I think it's strange timing that a belt issue arises immediately after I replace the Alternator. 1 Quote Link to comment
LiLHustler620 Posted March 29, 2015 Author Report Share Posted March 29, 2015 At this point I feel like taking it to a shop. But I really don't want to. I want to figure this out on my own. Call it a pride issue. 1 Quote Link to comment
Charlie69 Posted March 29, 2015 Report Share Posted March 29, 2015 Drive it down to Napa and have them come out and test battery and alternator for you. Quote Link to comment
ggzilla Posted March 29, 2015 Report Share Posted March 29, 2015 Stop throwing money at it. If the belt is loose it can cause all those symptoms. Get the correct length belt and tighten it to spec. Easy to do. A fresh battery reads about 12.6 volts. Never 14 volts, which is charging voltage. If you can turn the alternator by hand, the belt is way too loose! Quote Link to comment
620Turbo4X4 Posted March 29, 2015 Report Share Posted March 29, 2015 Ok so, I went ahead and got a new alternator. I installed it and charged my battery while doing so. After hooking everything back up I started up the motor and was pleased to see that the voltage while running was right around 14.5 v. I turned the headlights on and checked voltage again and it stayed the same. No drop. Problem solved right? Well then I go take her for a spin and run the headlights for a while and when I come back and check the voltage again 15 minutes later it's back down to 12+ v when running with lights on and when I turn the lights off it very slowly climbs back up to just barely over 13v. I thought I had solved the problem with the new alternator but now I'm even more confused. Well, if the pulley on new alt is not cut as deep as your old one, and belt is worn thin enough it could be bottoming out in the groove. Typically this doesn't make much of a squealing noise like you hear with just a loose belt. Couldn't hurt getting a new correctly sized belt and go from there.... 1 Quote Link to comment
LiLHustler620 Posted March 30, 2015 Author Report Share Posted March 30, 2015 Update! So although the voltage doesn't seem to be great the Alternator seems to be charging the battery. At least it hasn't drained it yet and I've been running with lights on. The belt still seems to have too much play but as I said before it is adjusted as tight as possible. Now however my fuel pump isn't working!? I feel like these things must be related somehow. When I unplug the electric pump and test the voltage that should be coming to the pump there is none. I pulled the fuel pump relay and checked the voltage in all the ports and everything except the fuel pump port shows good voltage. What do you think.. bad fuel pump or bad fuel pump relay? Or could there be another reason why my fuel pump doesn't work? ? Quote Link to comment
LiLHustler620 Posted March 30, 2015 Author Report Share Posted March 30, 2015 Also these fuel pump relays are hard to find Quote Link to comment
LiLHustler620 Posted March 30, 2015 Author Report Share Posted March 30, 2015 When the pump went out I also happened to run it out of fuel. Put new fuel in and very since it hasn't made a sound. Won't put fuel to the carb. Can't hear the pump running. But it fires with fuel put directly to the carb. Quote Link to comment
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