When car is running, the alternator big connection has only 12 v. or less. Alternator checked out good at autoparts store. I think Someone has miswired the lead going to the regulator when he replaced all the lights in front of the car. There is only one red wire going to the regulator, the plug has 4 prongs, 1 big and 3 small. I measured, but there is no voltage on the regulator wire whether the car is running or not. I think something has to energize the alternator through the reguilator for it to charge. Is that true? So there has to be some voltage on the regulator prong? But I don't know where is it wired to.
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Re: alternator not charging
Joe, there is no longer a regulator on this car as we would know it to be. The ecm is now also resposible for telling the alt when to turn on and off. This was done in order for the alt to be turned on and off in conjunction with the other loads and engine speed in order to be more efficiant in the long run. So from what I read here, you either have a bad wire somewhere or your ecm is toast. Replacing lights-unless for some reason the wires were cut(doubtfull) would have no effect on the alt.
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Easy way to check with a voltmeter. Check battery voltage on the battery terminals with key off, engine off, and then check voltage with engine running.
Engine off, a good battery should have voltage between 12.6 volts and 12.9 volts. With engine running, battery voltage should be a minimum of 13.5 volts, somewhere between 13.5 and 14.5 volts. This would indicate the alternator is good and is charging the battery. If voltage is less than 13.5 volts, if it only shows same volts as when not running, the alternator is not working right. Take it off and have tested for free at a parts store. It could be a bad alternator or it could be that the wiring between alternator and battery has a problem. If alternator tests good, start looking into the connections between alternator and battery.
Does your battery or alternator light stay on when engine is running? This would indicate a charging system problem. Time for the voltmeter test.
If the lights drain the battery when the engine is running, then you have a bigger problem of the alternator not charging, not working. When the engine is running, the alternator supplies all the current to run the car's electrical systems, while also charging up the battery for the next start-up. If you know the alternator is good, then maybe a fuse or fusible link has blown, preventing the alternator from working. To check, put a voltmeter on the battery with engine running-it should show over 13.5 volts if the charging system is working. If the alternator is not putting out, the voltmeter will read same voltage on the battery as when the engine is not running. A fully charged battery should show "around" 12.6 volts. A discharged battery will show less than 12 volts. That should give you an idea of the range to look for on a voltmeter. I believe some parts stores will check the voltage for free. I know most stores will test the alternator and battery for free if brought into the store, but you need the voltage read while on the car and engine running. If the system is charging normally and the lights kill everything, you may have a short in the lighting system.
When you say battery voltage how are you testing it? Are you looking at a gauge on the dash? Or are you physically testing it with a multi meter? If the truck is dying and you recently replaced the alternator and battery I would first suggest you to check all them connections again real good. Snug them all up. Check for corrosion and clean as needed. Did you replace the battery and alternator with new/re-manufactured battery and alternator? The alternator needs to put out at least 13.6 volts to charge your 12 volt battery or the battery will not maintain a charge. However the alternator runs the vehicle once it is started. The battery is used only to start the car and then the alternator runs it. So if your vehicle starts and runs and then dies you may have a bad alternator. Check your connections first and then test the alternator with a multi meter. Anything less than 13.6 volt will not suffice. 14+ volts would be the hopeful output of a good alternator.
Yes, the majority of vehicles can be started and then the battery completely removed from the vehicle and continue to run. If your Jeep dies and then wont restart (or is hesitant) because of a dead battery, this would most likely be the alternator connections, or event he alternator itself. Obviously the alternator is not supplying current to the vehicle. Most autopart stores can check the alternator for you, often free of charge and the easiest placed to start.
Hello, your Alternator has a fusible link of about 80 Amps to protect the electrical system. The big wire from the back of the Alternator needs to be tested by disconnecting the big wire and attaching an Ohmmeter to the loose end. The other end of the big wire will be found in a power connection and at that location you run a test wire to the other end of your Ohmmeter. It should complete a circuit. If it does not, the fusible link is blown. It needs to be replaced.
If the big wire does make a circuit, the problem is in the small 12 Volt wire going to the Alternator. Usually this is termed an "exciter" wire. It feeds the small voltage into the Alternator so big Amperage comes out. If this wire is dead you need to trace it back to the Ignition switch.
Your local Autoparts store, I know Autozone, Oreillys, and Advance will show pictures of the part and often locations. Sometimes you can look in the aftermarket shop manuals they sell and reference what you need. When your Alternator shorted it probably burned the fusible link.
Would like to know how you made out and if you found my solution useful.
The check battery light means that your car is running off the battery, and the charging system is not working. A good plan would be to recheck your battery cables and connections, then remove the alternator and have it checked. Most autoparts stores will do this for free. The alternator is the most likely suspect!
I'm an electrical engineer and the two solutions posted are spot on.
If it jumps and runs ok then all fuses and wiring are ok.
Most likely your alternator is not charging the battery effectivly. A voltmeter applied while it is running will show the charging voltage (if any). So in effect you are running on battery power only until the battery final dies and is recharged. The battery dies when you try to start (heavy amp load) but still has enough energy to handle the running load (much less power than starting).
Your alternator is charging however it is not still good if it does what you are stating. Also what is the condition of your battery if you have to keep jumping your car? Car batteries don't like to be completely discharge and may not hold there charge again once run dead and may need replaced... Alternator has to have be bad as it needs to be load tested to best determine it's true output. Most auto parts stores do a run test and no load test. Load test will tell amperage rate and true quality of an alternator.
ITS definitely the alternator if the voltage with vehicle running is less than 14Volts+ therefore the alternator is NOT charging enough, that why the battery LIGHT came ON. Replace alternator and that will solve your problem. Sometimes when alternator goes BAd they will actually have a drain on the battery. Good Luck and Thanks for using FIX YA