Skip the auto shop - Our mechanics make house calls

Q: Battery light goes on and off.

asked by on

I have replaced battery and alternator. Battery light keeps on coming and off. It has been going on for 2 months.

My car has 119000 miles.
My car has an automatic transmission.

A: Hi there. The battery light continuing to c...

Hi there. The battery light continuing to come on after battery and alternator replacement can be caused by other issues. First thing is to have the charging system checked by a certified technician.

Even though the alternator has been replaced, it is possible to have installed a defective part. Other caused can be a loose or broken wire between the battery and alternator. Also, a failing belt tensioner can be at fault. If the belt tensioner is weak and not keeping proper tension on the serpentine belt, the belt can slip and not spin the alternator at the proper speed. If this happens, a low voltage can occur and cause the battery light to come on. If you need to have a precise diagnosis for the battery light, a qualified professional from YourMechanic can come to your car's location to have this resolved.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Car only drives in reverse.

Sounds like you are having transmission issues. Low fluid levels in the transmission can cause issues like this. The problem is not all cars have easily accessible ways of checking the fluid. You can check your owners manual to see...

Q: New oil filter replaced 5 days after oil change

Hey there. Yes it can. The reason it could have been leaking is because maybe something hit the filter while driving or the rubber seal on it didn't seal properly. You can change the filter without changing the oil but...

Q: Oil leak after running over curb

Hi. It sounds like you may have a leak in your oil pan or transmission. You could have hit one or both of those when you hit the curb. If any leaks are existing, the oil pan or transmission would...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...