Battery light on over 55mph?
(2011-12-22 15:20:17) 1. Says: I was driving today, and I realized that my battery light was turning on over 55 miles per hour while passing someone. I didn't drive over 55 for the remainder of my 15 minute commute. Does anyone know what might be wrong? I searched online and it said maybe the alternator needs to be replaced, or the battery needs to be replaced. Help! I need to use my car daily and I don't know what's wrong!2. Says: If you would provide the vehicle information YMM (year, make, model) we may be able to make a diagnosis based on the symptoms provided, but without the vehicle info it is anyone's guess!EDIT: Thanks for the info, Yes, if the battery light is comming on at higher RPM's (over 55) this indicates the Alternator IS defective, If you take it to a shop this is how THIS vehicle should be diagnosed:
1. Check the Black/White (BK/WH) wire "B(+)" terminal of the alternator by checking voltage between it and the battery positive post with the engine running and the headlights and blower motor turned on. Voltage should indicate less than 100 millivolts (mV).
2. Check the White/Green (WH/GN) wire on the voltage regulator connection of the alternator by measuring voltage between it and the battery positive post with the connector plugged in and the headlights and blower motor turned on. Again voltage should indicate less than 100 mV.
3. Disconnect the voltage regulator connection and hold the RPM high to verify that the battery light stays off.
4. If voltage drop testing of the two circuits check to be OK and the light stays off with the voltage regulator connection unplugged, replace the alternator assembly!
ADDED: @ the other poster SHE didn't say it, the web search she did said it (for whatever that is worth)
ADDED: To the additional comment, from the asker, We don't take advantage of women or anyone else for that matter at my shop (because it doesn't make good business sense to do this if you want to keep customers) and I know of several other shops that have good reputations where I live. So it all depends on where you go! I would you do some research on a site such as citysearch.com of automotive shops in your town and go in there and read the reviews from other customers and see how their experience was!3. Says: Could be the battery, alternator or (old cars) a solenoid. Could also be a partial-short in the wiring but this is far less likely. As the L1 mechanic said, it would be easier to guess at if you provided the year, make and model of the vehicle.
You can go to some national auto parts stores (like Autozone) and ask them to do a simple battery check for free. They'll also often read a "check engine light" signal for free. You'll likely pay between $35 to $80 for most mechanics to do the same -- more than the $25 cost of a basic diagnostic code reader tool that you can order from Amazon and easily use yourself.4. Says: Change the alternator. If it was the battery it would do it at any speed, and you said it only happened while going faster. You will be able to limp by for a little while on it till payday if you clean your battery terminals and make sure they are good and tight, also make sure your battery cells are full of distilled water. Also make sure you don't run your headlights during the day time if at all possible. Basically don't run any extra electrical loads if you can help it like the heater blower, or the defroster.
But also know that if the light stays on no matter what, then the alternator or battey has failed completely, and it is time to drive to the nearest service center, or you will have to charge the battery again in order to start the engine, or get it towed.5. Says: Most likely alt. going bad, brushes bad or regulator which is inside alt. Take to certified shop they can check and give you an estimate of repair costs. Just explain what car is doing and let them diagnose.6. Says: I think Sear auto centers still do a free alternator/battery test. Tell them it happens on the highway and rev it up to highway speeds.7. Says: you said your self "alternator needs to be replaced" that's you answer8. Says: Take it to the dealership for an inspection just to be on the safe side. Tag: Battery light on over 55mph?