1990 Honda Accord 4 Doors LX, AT, 191,800 miles. Recently the battery light comes on and off right away occasionally while driving. It happens 0 to 2 times a day. Does that mean something is going to be failed? What problem could it be? Thanks!

 

Could be the battery or alternator. Bring it by a Autozone, they will check the voltage output of the alternator. With engine running, your alternator should have 13.5-14v. Your battery should have 12.5v.

 

Thanks! The battery light is solid on now when engine is running. Alternator belt tension looks good. I will check voltage tonight. I have a feeling the alternator (~ 19 years old) is failing. My car battery just changed a year ago with 100 months warrenty. What parts are tipically failed inside alternator? If alternator is bad, do I have to change for a new one? Or, I can fix parts inside alternator since a new alternator is expensive.

 

The windings withing the alternator usually go out. Sometime you can have these rebuilt if you have a local shop that does that sort of work. Autozone type stores sell rebuilt ones as well.

 

Battery light goes off again. Check voltage at battery, it has 11V with and without engine is running. I guess alternator is bad. Thanks!

 

previous posts are right on, check alternator and the battery at more than one place. Find a store that takes time to really give you great service. I am lucky to have a wide choice of parts stores and some are way better than others. The not so good ones will make selling you something their priority regardless of if that solves your problem.

 

Opps, forgot to soapbox about cleaning all possible connections in the electrical circut between the alt. and the batt. But clean them without current in the circut--don't want no arcin' & sparkin' if the wires make contact by accident.

 

Hi Diyman
How old is the regulator of your alternator?
Many times people thing the alternator is dead, when the regulator is exhausted. It is an item which brings electricity to the rotor and stops feeding electricity when voltage is too high.
It is rather simple to unscrew to check if brushes are still here. If brushes re not worn out, the transistor and diodes in the brushes' holder may be dying.
You an also check if the copper rings which are feeding electricity to the alternator are not completely worn out, but if they are unless you can find a good electrician who can fit new ones, the alternator is dead.
Cleaning all connections like Cbuddy2005 wrote is a good idea too.
Bye.
Marc

 

Hi Marcfr,

The regulator is as old as alternator and car since I own it new ~19 years. I will check brushes, regulator, diode, transistor, and copper rings. How can you tell regulator, transistor, and copper rings are good or bad? I have some electronic knowledge and know how to use multi-meter. One question, what kind of store except Honda dealers carries these type of parts if I found they are bad. Parts from Honda dealers are expensive and may very close to a whole rebuild/new OEM alternator. Thanks!

 

Hi Diyman 19 years old! Very good, you Honda is very reliable! Well, for checking the copper rings, it is simple, tyou unscrew the regulator, take it off ad you see the rings: if they are worn out, a part may be missing, and, at least, a new rotor must be found. For the regulator, in most situations brushes are worn out and the regulator must be changed. I do not know exactly who to test the electronics inside the regulator, mostly because it is sealed in a kind of plastic. On a european Ford I had twice the problem of an electronics failure! On the other cars the brushes had gone, an so replacement, but I have also known the case of worn out copper rings and had to find another alternator at the breaker's yard (it is dying again!!). The alternator's diodes are very sturdy now. To check them you have to undo the plastic cover to find them and using a multi meter on the diode position put the black lead on one side of a diode, the red lead on the other side of the diode and your multi meter should give a value on one side and nothing on the other side. The diode is good. Otherwise, if it gives nil or a value on both sides, the diode is dead. This happens very rarely. Now for finding parts outside the big robbers' shops (all car brands), I have been a regular customer at a local shop (I get a 20% to 40% rebate!!), but it is across the Atlantic! I do not know who the parts market is organized in the US but it seems similar. Try Graiglist for used parts. I have spotted some dealers like Advance Auto Parts, Carquest or Napa. Ask them their price and compare with Honda. Bye Marc

 

After change new brushes and have Kragen, Autozone, and alternator builder check, they all say it is good. Put back with new alternator, power steering belts, and connect wire back to alternator. Check battery before starting engine, it has 11.25V. Start engine, immediately alternator has hi pitch loud squeaking noise. Check battery, it has 13.25V. As soon as I disconnect wire (4 pins) from alternator while engine is still running, the noise is gone. Even I re-connect it back to alternator, there is no noise. Any idea? Bad diode, voltage regulator, or others?

 

The problem is because of loose belt. After tying it up, the noise is gone.