I took my 2002 taurus in because my alternator light was on...the first place Itook it to,the guy hooked it up to amachineand when he was done looking at it toldme I needed a new alternator.....The next day,I took my car to a different place and the guy hooked it up to thesame machine(a little newer)andwhen he was done told me there was nothing wrong with my alternator or battery and that I must have an eletrical problem inside the car because my alternator light is coming on for no reason........Do I need to get one more mechanics opinion,or just leave the car alone?............................By the way,I've had no problems and heard no noises out of the car...The light just started coming on a few days ago......................What to do?
2006-11-06 21:39:21 · 8 answers · asked by Direktor 5 in Cars & Transportation ➔ Maintenance & Repairs
Ok, here IS the answer from a real mechanic.
The Alternator on your vehicle has the ability to notify the operator if there is a charging system problem by grounding the battery light. This completes a series circuit for the instrumentation cluster when the zener diode contained in the regulator reverses bias. Without getting into too much mumbo jumbo on how that pesky light works (some manufacturers do it differently) the reality of the situation is that the alternator is probably defective and causing the problem.
This doesn't mean that the alternator isn't doing its intended job, it may just mean that that electrical section of the alternator is malfunctioning. The fact that the bulb in the dash comes on pretty much indicates the cluster is ok. Although there is a remote possibility that there is a short in the dash grounding the bulb. You can eliminate this by disconnecting the flat plug on the alternator and turning the Key to the run positoin without starting the engine. If the light is on, its in the dash, if its out, it needs an alternator.
Just because the voltage is above 12.6v does not mean that your alternator is working properly. That alternator has three windings in the stator and its not uncommon one will burn out causing the alternator to 'full field" or increase the duty cycle of the field collective to maintain amperage output. This can be checked easily by a good technician with an oscilloscope checking for alternator voltage ripple.
Ok, I got long winded, and I guess as a consumer what you need to do is go to one more mechanic to have it checked properly. I really do lean towards the first mechanic. Those charging system analyzers that the mechanics are using do not give anything other than charging and starting data. They cant tell you why its not working. Thats where the diagnosis of a good technician comes to play.
Alternators do not charge between 14 and 16 volts. The target voltage of most vehicles is 14.7. If you are seeing above 15 v there is a problem with a connection or the battery cells. Fuel pumps, computers ect actually only need 10V to operate properly and most sensors and feedback items are regulated at 5v and 10v. It is not uncommon to see late model cars charging at 13.7-13.9 V at idle and under load. PCM controlled pulse modulated fields in new alternators IE ford and chrylser we have seen charging voltages at even lower than 13.5. The key is not the voltage but the amperage that is supplied back to the battery. The only reason the alternator produces a higher voltage than the battery is so that the battery becomes the load in the circuit and recieves its charge rate. You can also purchase a very inexpensive tool called a hydrometer for batteries. By drawing battery fluid up to the chamber you can measure the specific gravity of the electrolyte and see the actual state of charge of the battery. This won't tell you if your battery is able to supply the necc current for proper operation, but it will tell you if your output exceeds your input while driving. Hydrometers are less than 5 bucks.
Hope you get it fixed!
2006-11-06 22:43:48 · answer #1 · answered by Wayne H 2 · 0⤊ 0⤋
NO MECHANICS THEY WILL GET YOU TO BELIEVE CRAP. Take it to a auto store they will do it right in front of you and you can ask any questions for free. Car should be running when they check the alternator. They can tell that the alternator is charging your battery at all and if it is strong. Also sounds like bad connections. If you alternator is going out your headlights may flicker or your radio things will start to go dim then come back strong. Have a test run on it at the store too they can get codes on your car and tell you what they mean for free too. Start there then work your way to a mechanic if needed. Alternators are generally easy to replace. Just doesnt seem right in your car only being a few years old.
2006-11-06 22:38:38 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Your alternator is bad. The light on your dash is right and the second guy to check it for you was wrong. Your alternator should put out between 14 and 16 volts. I am guessing that the second guy saw that it is producing around 13 volts so he is thinking it will be OK. He is wrong. Because your car has an electric fuel pump kind all kinds of sensors and probably power windows and seats etc... 13 volts is not enough. Also you might want to replace the alternator soon because a bad alternator will destroy your battery and then you ill end up buying both. Hope I have been helpful.
2006-11-06 21:53:34 · answer #3 · answered by king_davis13 7 · 1⤊ 0⤋
get another apoinon as i am a mechanic
you need to say to the next man im not just a normal girl i know about cars and you will
can you test the charge rate of my alternator with my lights on high beam as i do not have a multi meter to test why my charge rate because my light is on be sore it is the charging light
then you need to say what is the max charge rate it is doing about 14.3volts to 14.8volts max with light on and it will drop down to maybe about 13.8volts about before start charging agian like a fridge cooler it keeps it about the disired temputer
then you need to say if ok so why my light is on can you give me a quote and report on work to fix it
if is alternator you then need a quote and report to fix it to
when quote is aranged you need to say if any other problems that you may encounter call me first this is very important this is where you can get ripped off
after quoted and have a report entre it on yahoo and ask if this is ok and if im in time i will have a look at it but im not good at prices as im in new zealand i can only give advice on jobs and times not prices ok good luck
dane'o
2006-11-06 22:19:57 · answer #4 · answered by Dane'o 3 · 0⤊ 0⤋
i agree with the first mechanic you took your car to, because alternator sometime are hard to check unless they are completely gone bad, when he checked it might work but it not pull the amps like it suppose too and your battery still fully charged that why right now your car is still running , when your battery is getting weak of cause it will because your alternator don't put out enough amps to recharge your battery, then eventually your car will not start because not enough amps to turn the starter over by them you have to change your alternator and your battery too.
2006-11-06 22:08:45 · answer #5 · answered by pvphelp 2 · 1⤊ 0⤋
If the engine keeps running at a good idle, as you disconnect the battery cable, then the charging system is working and the alternator is ok.
2006-11-06 21:51:20 · answer #6 · answered by Anonymous · 0⤊ 0⤋
I would take it to at least 1 or 2 more mechanics and see what they say.
2006-11-06 21:47:03 · answer #7 · answered by ezachowski 6 · 1⤊ 0⤋
DO NOT CHECK BY UNHOOKING BATTERY CABLE. ON NEWER CARS, YOU MAY HURT COMPUTER, SENSORS,ETC!!!!!
2006-11-06 22:13:55 · answer #8 · answered by midnighttoker 3 · 0⤊ 0⤋