Repair Topics / Alternator

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Car Alternator System Questions and Answers

This category contains featured questions as examples. They relate to most vehicles.

Question: 1998 Chevrolet 1500 Long Bed, 87,000 miles, Hello, I have a problem with my truck it sounds like the transmission is going out. My friend said had had the same problem and a alternator repaired the problem. Can this be so? do alternators make this grumbling noise when going out?

Answer: Yes, we just had a Chevy truck come in for that same problem. The easiest way to see if it is your alternator is to remove the drive belt them start it for a moment, did the noise go away? if yes, replace alternator with high quality rebuilt unit.

Question:  2001 Chrysler pt cruiser 2.4 non TC_mileage: 51,000. Bob and Ken, my wife has a 2001 PT Cruiser and she loves it normally. She had been in Korea for 18 months because I live and work here for the government as an FAA, A&P mechanic. My cousin drove the car once a week to grocery shop and such while my wife was here in Korea with me. The power steering pump started leaking at 41,000 and we had it replaced. My wife returned to the U.S. in March and about 2,000 miles of driving the alternator went out. This car has a generator according to what I could read on line. The generator was replaced along with the battery and the cable harness assembly due to corrosion. About a month later the battery light came on again. She took it to the dealer and they replaced the generator and did a couple of diagnostic tests and said the computer has no faults listed. She insisted that the computer needed to be replaced because she also had strange lights turning on with no inputs from her, turn signals, fog lights, dash lights. 

They of course said that the diagnostic tests showed nothing and that it would be fine. Well, here we are about three weeks later and low and behold the battery light comes on again. She has left the car at a different dealer now and I am very curious to see what they said. They have already said that the diagnostic tests showed no faults to include the battery light coming on, which the mechanic witnessed.  I have worked on helicopters for the last twenty years and also race go karts and a highly modified BMW 2002 Ti. I am not a know it all, but from what I can see online of the wiring diagram, the voltage regulator is inside the PCM (Chrysler term for the computer). I would think this is the place to look, but it seems the dealer's don't want to admit that it has a bad PCM.  I am frustrated at the situation because I am here in Korea and there is no family in the immediate area to help her. I worry that she will break down in the middle of nowhere and so on. Thanks for your input. 

Answer:  This is a classic example of what happens when a budget alternator is installed. Make sure only top quality replacement parts are installed. Sometimes these parts cost a little more but to avoid frustration it is worth it. If the alternator that has been installed is a top quality unit, it is our opinion that you have a main control module or PCM that is failing.

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Question: 1997 Honda Accord with 70,000. We purchased a used Honda about a year ago for my daughter. One meticulous previous owner with a little black book with all records kept it in great condition. About 2 months ago, the battery light went on and then her car went dead. We jumped it a few times and got it in for a check. It was the alternator. I had it replaced. Less than a month later, the battery light went on, and it was the alternator again. The parts distributor replaced and even reimbursed 1/2 of the mechanic's fee.

They checked the battery, and it was fine when I had the service done and the new alternator put in. Again today, the light went on. It has only been two weeks! What in the world is happening? I am afraid to let her drive it. Other than that, the only thing I have had replaced was the ignition switch in January. I am embarrassed to go back to the parts distributor...they really have been great, but in the meantime I'm wasting a ton of money on mechanic's fees.

Answer:  Again, a classic example of what happens when a budget alternator is installed. Make sure only top quality replacement parts are installed. Sometimes these parts cost a little more but to avoid frustration it is worth it. If the alternator was top quality, you wouldn't be having these inconveniences. We cant stress enough, "cheap car parts aren't cheap!" stay away from auto parts like "Autozone, Napa, etc. (lifetime warranties) you will be changing them the rest of your life. Opt for parts ware houses that supply to the public, who give you OEM quality parts and low prices.

Question: 1999 Mercury Grand Marquis mileage: 50,000.  Refresh my memory a bit; forgot how to check if my alternator itself is ok.  Alternator currently in vehicle was rebuilt and boosted to 100 amps instead of the normal 65-70-amp type.  Your response would be greatly appreciated.  Thank you.

Answer: If the battery in your car is in good condition, you can check the alternator by having the engine on.  The voltage across the battery terminals should be 13.5 to 14.5 volts. Double check to see that the alternator belt is tensioned properly and in good condition.

Question: 1998 Dodge 2500 Ram Van mileage: 80,000.  The alternator was not charging - had new brushes put in.  Since then, once in awhile the alternator will go to full charge and the lights will get over bright.  Some say it is the voltage regulator but we cannot find it.  It is not in the alternator and it is not on the firewall some say it's built into the computer.  It only does it once in awhile but I'm afraid it is going to burn out my headlights when it does it.  Thank for your help.

Answer:  If the alternator armature was not resurfaced at the time of brush installation there is no way for the alternator brushes to mate squarely to the connector ring. Therefore inhibiting the operation. Replace the alternator with a top quality unit.

Question: 1998 Ford Ranger mileage: 49,000.  A few weeks ago, my charge light started coming on intermittently, and my battery has since died. The alternator is putting out (the exact amps I do not know).  I found this out using some shade tree methods (removing cables while engine is running, feeling magnetic pull on back of alternator).  I have since replaced the battery, and the charge light still comes on, however it stops glowing at idle with the headlamps on.  It will appear again upon acceleration.  Any ideas?

Answer:  1. Do not ever remove battery cables form the vehicle while running. The Computer system in the car uses a battery to act like a shock absorber for the system, electrically. This can damage your computer component causing extreme $$$. 2. Your charge light is on because the diodes inside the alternator are faulty. Replace alternator with high quality rebuilt unit.

Question: 2002 Ford / F150 mileage: 55,000.  I have a problem.  I think it is my alternator, but I am a little unsure.  Periodically, my lights dim and everything electrical will slow (ac, heater, etc.).  After a short period, they will return to normal.  At first I thought it might be a short, but it does not occur when I hit a bump nor does it go away on bumpy roads (once it stopped while sitting still).  The last time it happened, my truck stalled when I stopped.  It wouldn't restart.  Then, about an hour later, it started as if nothing was wrong.  Any ideas?  I'm lost.

Answer:  Yes, it sounds like your alternator is short circuiting internally. Replace alternator with high quality rebuilt unit.

Question: 1999 Ford Windstar mileage: 35,000.  My Windstar runs on just battery power.  I have changed the alternator and checked all of the wires.  It will run for about 5 miles on a fully charged battery before the battery is completely drained.  Do you have any suggestions?

Answer:  Yes, it sounds like your alternator is short circuited internally. Replace alternator with high quality rebuilt unit.

Question: 2001 Ford Focus mileage: 120,000.  The battery light suddenly came on and with a volt meter reading on the battery showing 13.5V not running and slowly drops to 12.3V when the engine is running.  I believe the alternator is not charging.  However, before I buy a rebuilt alternator could it be something else? 

Answer:   No, this drop in voltage is normal as the surface voltage is depleted to the regular standing voltage of the car. You still need a alternator though. Replace alternator with high quality rebuilt unit.

Question: 1998 Toyota Celica, 120,000 miles, Hi, I have a problem I hope you can help. I drive my car almost every day so it doesn't sit around. At the end of the day the charge light will flicker and then go out. Do you know what could be the problem?

Answer: Yes, your alternator is getting ready to go out. Replace alternator with high quality rebuilt unit.

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